NASM 0.95

[platform/upstream/nasm.git] / preproc.c

/* preproc.c   macro preprocessor for the Netwide Assembler
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 *
 * initial version 18/iii/97 by Simon Tatham
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>

#include "nasm.h"
#include "nasmlib.h"

typedef struct SMacro SMacro;
typedef struct MMacro MMacro;
typedef struct Context Context;
typedef struct Token Token;
typedef struct Line Line;
typedef struct Include Include;
typedef struct Cond Cond;
typedef struct IncPath IncPath;

/*
 * Store the definition of a single-line macro.
 */
struct SMacro {
    SMacro *next;
    char *name;
    int casesense;
    int nparam;
    int in_progress;
    Token *expansion;
};

/*
 * Store the definition of a multi-line macro.
 */
struct MMacro {
    MMacro *next;
    char *name;
    int casesense;
    int nparam_min, nparam_max;
    int plus;                          /* is the last parameter greedy? */
    int nolist;                        /* is this macro listing-inhibited? */
    int in_progress;
    Token **defaults, *dlist;
    Line *expansion;
};

/*
 * The context stack is composed of a linked list of these.
 */
struct Context {
    Context *next;
    SMacro *localmac;
    char *name;
    unsigned long number;
};

/*
 * This is the internal form which we break input lines up into.
 * Typically stored in linked lists.
 *
 * TOK_PS_OTHER is a token type used internally within
 * expand_smacro(), to denote a token which has already been
 * checked for being a potential macro, but may still be a context-
 * local label.
 *
 * Note that `type' serves a double meaning: TOK_SMAC_PARAM is not
 * necessarily used as-is, but is intended to denote the number of
 * the substituted parameter. So in the definition
 *
 *     %define a(x,y) ( (x) & ~(y) )
 * 
 * the token representing `x' will have its type changed to
 * TOK_SMAC_PARAM, but the one representing `y' will be
 * TOK_SMAC_PARAM+1.
 *
 * TOK_INTERNAL_STRING is a dirty hack: it's a single string token
 * which doesn't need quotes around it. Used in the pre-include
 * mechanism as an alternative to trying to find a sensible type of
 * quote to use on the filename we were passed.
 */
struct Token {
    Token *next;
    char *text;
    SMacro *mac;                       /* associated macro for TOK_MAC_END */
    int type;
};
enum {
    TOK_WHITESPACE = 1, TOK_COMMENT, TOK_ID, TOK_PREPROC_ID, TOK_STRING,
    TOK_NUMBER, TOK_SMAC_END, TOK_OTHER, TOK_PS_OTHER, TOK_SMAC_PARAM,
    TOK_INTERNAL_STRING
};

/*
 * Multi-line macro definitions are stored as a linked list of
 * these, which is essentially a container to allow several linked
 * lists of Tokens.
 * 
 * Note that in this module, linked lists are treated as stacks
 * wherever possible. For this reason, Lines are _pushed_ on to the
 * `expansion' field in MMacro structures, so that the linked list,
 * if walked, would give the macro lines in reverse order; this
 * means that we can walk the list when expanding a macro, and thus
 * push the lines on to the `expansion' field in _istk_ in reverse
 * order (so that when popped back off they are in the right
 * order). It may seem cockeyed, and it relies on my design having
 * an even number of steps in, but it works...
 *
 * Some of these structures, rather than being actual lines, are
 * markers delimiting the end of the expansion of a given macro.
 * This is for use in the cycle-tracking code. Such structures have
 * `finishes' non-NULL, and `first' NULL. All others have
 * `finishes' NULL, but `first' may still be NULL if the line is
 * blank.
 */
struct Line {
    Line *next;
    MMacro *finishes;
    Token *first;
};

/*
 * To handle an arbitrary level of file inclusion, we maintain a
 * stack (ie linked list) of these things.
 */
struct Include {
    Include *next;
    FILE *fp;
    Cond *conds;
    Line *expansion;
    char *fname;
    int lineno, lineinc;
};

/*
 * Include search path. This is simply a list of strings which get
 * prepended, in turn, to the name of an include file, in an
 * attempt to find the file if it's not in the current directory.
 */
struct IncPath {
    IncPath *next;
    char *path;
};

/*
 * Conditional assembly: we maintain a separate stack of these for
 * each level of file inclusion. (The only reason we keep the
 * stacks separate is to ensure that a stray `%endif' in a file
 * included from within the true branch of a `%if' won't terminate
 * it and cause confusion: instead, rightly, it'll cause an error.)
 */
struct Cond {
    Cond *next;
    int state;
};
enum {
    /*
     * These states are for use just after %if or %elif: IF_TRUE
     * means the condition has evaluated to truth so we are
     * currently emitting, whereas IF_FALSE means we are not
     * currently emitting but will start doing so if a %else comes
     * up. In these states, all directives are admissible: %elif,
     * %else and %endif. (And of course %if.)
     */
    COND_IF_TRUE, COND_IF_FALSE,
    /*
     * These states come up after a %else: ELSE_TRUE means we're
     * emitting, and ELSE_FALSE means we're not. In ELSE_* states,
     * any %elif or %else will cause an error.
     */
    COND_ELSE_TRUE, COND_ELSE_FALSE,
    /*
     * This state means that we're not emitting now, and also that
     * nothing until %endif will be emitted at all. It's for use in
     * two circumstances: (i) when we've had our moment of emission
     * and have now started seeing %elifs, and (ii) when the
     * condition construct in question is contained within a
     * non-emitting branch of a larger condition construct.
     */
    COND_NEVER
};
#define emitting(x) ( (x) == COND_IF_TRUE || (x) == COND_ELSE_TRUE )

/*
 * Condition codes. Note that we use c_ prefix not C_ because C_ is
 * used in nasm.h for the "real" condition codes. At _this_ level,
 * we treat CXZ and ECXZ as condition codes, albeit non-invertible
 * ones, so we need a different enum...
 */
static char *conditions[] = {
    "a", "ae", "b", "be", "c", "cxz", "e", "ecxz", "g", "ge", "l", "le",
    "na", "nae", "nb", "nbe", "nc", "ne", "ng", "nge", "nl", "nle", "no",
    "np", "ns", "nz", "o", "p", "pe", "po", "s", "z"
};
enum {
    c_A, c_AE, c_B, c_BE, c_C, c_CXZ, c_E, c_ECXZ, c_G, c_GE, c_L, c_LE,
    c_NA, c_NAE, c_NB, c_NBE, c_NC, c_NE, c_NG, c_NGE, c_NL, c_NLE, c_NO,
    c_NP, c_NS, c_NZ, c_O, c_P, c_PE, c_PO, c_S, c_Z
};
static int inverse_ccs[] = {
    c_NA, c_NAE, c_NB, c_NBE, c_NC, -1, c_NE, -1, c_NG, c_NGE, c_NL, c_NLE,
    c_A, c_AE, c_B, c_BE, c_C, c_E, c_G, c_GE, c_L, c_LE, c_O, c_P, c_S,
    c_Z, c_NO, c_NP, c_PO, c_PE, c_NS, c_NZ
};

static Context *cstk;
static Include *istk;
static IncPath *ipath = NULL;

static efunc error;

static unsigned long unique;           /* unique identifier numbers */

static char *linesync, *outline;

static Line *predef = NULL;

static ListGen *list;

/*
 * The number of hash values we use for the macro lookup tables.
 */
#define NHASH 31

/*
 * The current set of multi-line macros we have defined.
 */
static MMacro *mmacros[NHASH];

/*
 * The current set of single-line macros we have defined.
 */
static SMacro *smacros[NHASH];

/*
 * The multi-line macro we are currently defining, if any.
 */
static MMacro *defining;

/*
 * The number of macro parameters to allocate space for at a time.
 */
#define PARAM_DELTA 16

/*
 * The standard macro set: defined as `static char *stdmac[]'. Also
 * gives our position in the macro set, when we're processing it.
 */
#include "macros.c"
static char **stdmacpos;

/*
 * The pre-preprocessing stage... This function translates line
 * number indications as they emerge from GNU cpp (`# lineno "file"
 * flags') into NASM preprocessor line number indications (`%line
 * lineno file').
 */
static char *prepreproc(char *line) {
    int lineno, fnlen;
    char *fname, *oldline;

    if (line[0] == '#' && line[1] == ' ') {
        oldline = line;
        fname = oldline+2;
        lineno = atoi(fname);
        fname += strspn(fname, "0123456789 ");
        if (*fname == '"')
            fname++;
        fnlen = strcspn(fname, "\"");
        line = nasm_malloc(20+fnlen);
        sprintf(line, "%%line %d %.*s", lineno, fnlen, fname);
        nasm_free (oldline);
    }
    return line;
}

/*
 * The hash function for macro lookups. Note that due to some
 * macros having case-insensitive names, the hash function must be
 * invariant under case changes. We implement this by applying a
 * perfectly normal hash function to the uppercase of the string.
 */
static int hash(char *s) {
    /*
     * Powers of three, mod 31.
     */
    static const int multipliers[] = {
        1, 3, 9, 27, 19, 26, 16, 17, 20, 29, 25, 13, 8, 24, 10,
        30, 28, 22, 4, 12, 5, 15, 14, 11, 2, 6, 18, 23, 7, 21
    };
    int h = 0;
    int i = 0;

    while (*s) {
        h += multipliers[i] * (unsigned char) (toupper(*s));
        s++;
        if (++i >= sizeof(multipliers)/sizeof(*multipliers))
            i = 0;
    }
    h %= NHASH;
    return h;
}

/*
 * Free a linked list of tokens.
 */
static void free_tlist (Token *list) {
    Token *t;
    while (list) {
        t = list;
        list = list->next;
        nasm_free (t->text);
        nasm_free (t);
    }
}

/*
 * Free a linked list of lines.
 */
static void free_llist (Line *list) {
    Line *l;
    while (list) {
        l = list;
        list = list->next;
        free_tlist (l->first);
        nasm_free (l);
    }
}

/*
 * Pop the context stack.
 */
static void ctx_pop (void) {
    Context *c = cstk;
    SMacro *smac, *s;

    cstk = cstk->next;
    smac = c->localmac;
    while (smac) {
        s = smac;
        smac = smac->next;
        nasm_free (s->name);
        free_tlist (s->expansion);
        nasm_free (s);
    }
    nasm_free (c->name);
    nasm_free (c);
}

/*
 * Generate a line synchronisation comment, to ensure the assembler
 * knows which source file the current output has really come from.
 */
static void line_sync (void) {
    char text[80];
    sprintf(text, "%%line %d+%d %s",
            (istk->expansion ? istk->lineno - istk->lineinc : istk->lineno),
            (istk->expansion ? 0 : istk->lineinc), istk->fname);
    if (linesync)
        free (linesync);
    linesync = nasm_strdup(text);
}

#define BUF_DELTA 512
/*
 * Read a line from the top file in istk, handling multiple CR/LFs
 * at the end of the line read, and handling spurious ^Zs. Will
 * return lines from the standard macro set if this has not already
 * been done.
 */
static char *read_line (void) {
    char *buffer, *p, *q;
    int bufsize;

    if (stdmacpos) {
        if (*stdmacpos) {
            char *ret = nasm_strdup(*stdmacpos++);
            /*
             * Nasty hack: here we push the contents of `predef' on
             * to the top-level expansion stack, since this is the
             * most convenient way to implement the pre-include and
             * pre-define features.
             */
            if (!*stdmacpos) {
                Line *pd, *l;
                Token *head, **tail, *t, *tt;

                for (pd = predef; pd; pd = pd->next) {
                    head = NULL;
                    tail = &head;
                    for (t = pd->first; t; t = t->next) {
                        tt = *tail = nasm_malloc(sizeof(Token));
                        tt->next = NULL;
                        tail = &tt->next;
                        tt->type = t->type;
                        tt->text = nasm_strdup(t->text);
                        tt->mac = t->mac;   /* always NULL here, in fact */
                    }
                    l = nasm_malloc(sizeof(Line));
                    l->next = istk->expansion;
                    l->first = head;
                    l->finishes = FALSE;
                    istk->expansion = l;
                }
            }
            return ret;
        } else {
            stdmacpos = NULL;
            line_sync();
        }
    }

    bufsize = BUF_DELTA;
    buffer = nasm_malloc(BUF_DELTA);
    p = buffer;
    while (1) {
        q = fgets(p, bufsize-(p-buffer), istk->fp);
        if (!q)
            break;
        p += strlen(p);
        if (p > buffer && p[-1] == '\n') {
            istk->lineno += istk->lineinc;
            break;
        }
        if (p-buffer > bufsize-10) {
            bufsize += BUF_DELTA;
            buffer = nasm_realloc(buffer, bufsize);
        }
    }

    if (!q && p == buffer) {
        nasm_free (buffer);
        return NULL;
    }

    /*
     * Play safe: remove CRs as well as LFs, if any of either are
     * present at the end of the line.
     */
    while (p > buffer && (p[-1] == '\n' || p[-1] == '\r'))
        *--p = '\0';

    /*
     * Handle spurious ^Z, which may be inserted into source files
     * by some file transfer utilities.
     */
    buffer[strcspn(buffer, "\032")] = '\0';

    list->line (LIST_READ, buffer);

    return buffer;
}

/*
 * Tokenise a line of text. This is a very simple process since we
 * don't need to parse the value out of e.g. numeric tokens: we
 * simply split one string into many.
 */
static Token *tokenise (char *line) {
    char *p = line;
    int type;
    Token *list = NULL;
    Token *t, **tail = &list;

    while (*line) {
        p = line;
        if (*p == '%' &&
            (p[1] == '{' || p[1] == '!' || (p[1] == '%' && isidchar(p[2])) ||
             p[1] == '$' || p[1] == '+' || p[1] == '-' || isidchar(p[1]))) {
            type = TOK_PREPROC_ID;
            p++;
            if (*p == '{') {
                p++;
                while (*p && *p != '}') {
                    p[-1] = *p;
                    p++;
                }
                p[-1] = '\0';
                if (*p) p++;
            } else {
                if (*p == '!' || *p == '%' || *p == '$' ||
                    *p == '+' || *p == '-') p++;
                while (*p && isidchar(*p))
                    p++;
            }
        } else if (isidstart(*p)) {
            type = TOK_ID;
            p++;
            while (*p && isidchar(*p))
                p++;
        } else if (*p == '\'' || *p == '"') {
            /*
             * A string token.
             */
            char c = *p;
            p++;
            type = TOK_STRING;
            while (*p && *p != c)
                p++;
            if (*p) p++;
        } else if (isnumstart(*p)) {
            /*
             * A number token.
             */
            type = TOK_NUMBER;
            p++;
            while (*p && isnumchar(*p))
                p++;
        } else if (isspace(*p)) {
            type = TOK_WHITESPACE;
            p++;
            while (*p && isspace(*p))
                p++;
            /*
             * Whitespace just before end-of-line is discarded by
             * pretending it's a comment; whitespace just before a
             * comment gets lumped into the comment.
             */
            if (!*p || *p == ';') {
                type = TOK_COMMENT;
                while (*p) p++;
            }
        } else if (*p == ';') {
            type = TOK_COMMENT;
            while (*p) p++;
        } else {
            /*
             * Anything else is an operator of some kind; with the
             * exceptions of >>, <<, // and %%, all operator tokens
             * are single-character.
             */
            char c = *p++;
            type = TOK_OTHER;
            if ( (c == '>' || c == '<' || c == '/' || c == '%') && *p == c)
                p++;
        }
        if (type != TOK_COMMENT) {
            *tail = t = nasm_malloc (sizeof(Token));
            tail = &t->next;
            t->next = NULL;
            t->type = type;
            t->text = nasm_malloc(1+p-line);
            strncpy(t->text, line, p-line);
            t->text[p-line] = '\0';
        }
        line = p;
    }

    return list;
}

/*
 * Convert a line of tokens back into text.
 */
static char *detoken (Token *tlist) {
    Token *t;
    int len;
    char *line, *p;

    len = 0;
    for (t = tlist; t; t = t->next) {
        if (t->type == TOK_PREPROC_ID && t->text[1] == '!') {
            char *p = getenv(t->text+2);
            nasm_free (t->text);
            if (p)
                t->text = nasm_strdup(p);
            else
                t->text = NULL;
        }
        if (t->text)
            len += strlen(t->text);
    }
    p = line = nasm_malloc(len+1);
    for (t = tlist; t; t = t->next) {
        if (t->text) {
            strcpy (p, t->text);
            p += strlen(p);
        }
    }
    *p = '\0';
    return line;
}

/*
 * Return the Context structure associated with a %$ token. Return
 * NULL, having _already_ reported an error condition, if the
 * context stack isn't deep enough for the supplied number of $
 * signs.
 */
static Context *get_ctx (char *name) {
    Context *ctx;
    int i;

    if (!cstk) {
        error (ERR_NONFATAL|ERR_OFFBY1, "`%s': context stack is empty", name);
        return NULL;
    }

    i = 1;
    ctx = cstk;
    while (name[i+1] == '$') {
        i++;
        ctx = ctx->next;
        if (!ctx) {
            error (ERR_NONFATAL|ERR_OFFBY1, "`%s': context stack is only"
                   " %d level%s deep", name, i-1, (i==2 ? "" : "s"));
            return NULL;
        }
    }
    return ctx;
}

/*
 * Compare a string to the name of an existing macro; this is a
 * simple wrapper which calls either strcmp or nasm_stricmp
 * depending on the value of the `casesense' parameter.
 */
static int mstrcmp(char *p, char *q, int casesense) {
    return casesense ? strcmp(p,q) : nasm_stricmp(p,q);
}

/*
 * Open an include file. This routine must always return a valid
 * file pointer if it returns - it's responsible for throwing an
 * ERR_FATAL and bombing out completely if not. It should also try
 * the include path one by one until it finds the file or reaches
 * the end of the path.
 */
static FILE *inc_fopen(char *file) {
    FILE *fp;
    char *prefix = "", *combine;
    IncPath *ip = ipath;
    int len = strlen(file);

    do {
        combine = nasm_malloc(strlen(prefix)+len+1);
        strcpy(combine, prefix);
        strcat(combine, file);
        fp = fopen(combine, "r");
        nasm_free (combine);
        if (fp)
            return fp;
        prefix = ip ? ip->path : NULL;
        if (ip)
            ip = ip->next;
    } while (prefix);

    error (ERR_FATAL|ERR_OFFBY1,
           "unable to open include file `%s'", file);
    return NULL;                       /* never reached - placate compilers */
}

/*
 * Determine if we should warn on defining a single-line macro of
 * name `name', with `nparam' parameters. If nparam is 0, will
 * return TRUE if _any_ single-line macro of that name is defined.
 * Otherwise, will return TRUE if a single-line macro with either
 * `nparam' or no parameters is defined.
 *
 * If a macro with precisely the right number of parameters is
 * defined, the address of the definition structure will be
 * returned in `defn'; otherwise NULL will be returned. If `defn'
 * is NULL, no action will be taken regarding its contents, and no
 * error will occur.
 *
 * Note that this is also called with nparam zero to resolve
 * `ifdef'.
 */
static int smacro_defined (char *name, int nparam, SMacro **defn) {
    SMacro *m;
    Context *ctx;
    char *p;

    if (name[0] == '%' && name[1] == '$') {
        ctx = get_ctx (name);
        if (!ctx)
            return FALSE;              /* got to return _something_ */
        m = ctx->localmac;
        p = name+1;
        p += strspn(p, "$");
    } else {
        m = smacros[hash(name)];
        p = name;
    }

    while (m) {
        if (!mstrcmp(m->name, p, m->casesense) &&
            (nparam == 0 || m->nparam == 0 || nparam == m->nparam)) {
            if (defn) {
                if (nparam == m->nparam)
                    *defn = m;
                else
                    *defn = NULL;
            }
            return TRUE;
        }
        m = m->next;
    }
    return FALSE;
}

/*
 * Count and mark off the parameters in a multi-line macro call.
 * This is called both from within the multi-line macro expansion
 * code, and also to mark off the default parameters when provided
 * in a %macro definition line.
 */
static void count_mmac_params (Token *t, int *nparam, Token ***params) {
    int paramsize, brace;

    *nparam = paramsize = 0;
    *params = NULL;
    while (t) {
        if (*nparam >= paramsize) {
            paramsize += PARAM_DELTA;
            *params = nasm_realloc(*params, sizeof(**params) * paramsize);
        }
        if (t && t->type == TOK_WHITESPACE)
            t = t->next;
        brace = FALSE;
        if (t && t->type == TOK_OTHER && !strcmp(t->text, "{"))
            brace = TRUE;
        (*params)[(*nparam)++] = t;
        while (t && (t->type != TOK_OTHER ||
                     strcmp(t->text, brace ? "}" : ",")))
            t = t->next;
        if (t) {                       /* got a comma/brace */
            t = t->next;
            if (brace) {
                /*
                 * Now we've found the closing brace, look further
                 * for the comma.
                 */
                if (t && t->type == TOK_WHITESPACE)
                    t = t->next;
                if (t && (t->type != TOK_OTHER || strcmp(t->text, ","))) {
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "braces do not enclose all of macro parameter");
                    while (t && (t->type != TOK_OTHER ||
                                 strcmp(t->text, ",")))
                        t = t->next;
                }
                if (t)
                    t = t->next;               /* eat the comma */
            }
        }
        else                           /* got EOL */
            break;
    }
}

/*
 * Find out if a line contains a preprocessor directive, and deal
 * with it if so.
 * 
 * If a directive _is_ found, the line will never be de-tokenised
 * as is, so we have carte blanche to fiddle with it and adjust
 * token values.
 *
 * Return values go like this:
 * 
 * bit 0 is set if a directive was found
 * bit 1 is set if a blank line should be emitted
 * bit 2 is set if a re-sync line number comment should be emitted
 *
 * (bits 1 and 2 are mutually exclusive in that the rest of the
 * preprocessor doesn't guarantee to be able to handle the case in
 * which both are set)
 */
static int do_directive (Token *tline) {
    static char *directives[] = {
        "%clear", "%define", "%elifctx", "%elifdef", "%elifnctx",
        "%elifndef", "%else", "%endif", "%endm", "%endmacro", "%error",
        "%idefine", "%ifctx", "%ifdef", "%ifnctx", "%ifndef", "%imacro",
        "%include", "%line", "%macro", "%pop", "%push", "%repl"
    };
    enum {
        PP_CLEAR, PP_DEFINE, PP_ELIFCTX, PP_ELIFDEF, PP_ELIFNCTX,
        PP_ELIFNDEF, PP_ELSE, PP_ENDIF, PP_ENDM, PP_ENDMACRO, PP_ERROR,
        PP_IDEFINE, PP_IFCTX, PP_IFDEF, PP_IFNCTX, PP_IFNDEF, PP_IMACRO,
        PP_INCLUDE, PP_LINE, PP_MACRO, PP_POP, PP_PUSH, PP_REPL
    };
    int i, j, k, m, nparam;
    char *p, *mname;
    Include *inc;
    Context *ctx;
    Cond *cond;
    SMacro *smac, **smhead;
    MMacro *mmac;
    Token *t, *tt, *param_start, *macro_start, *last;

    if (tline && tline->type == TOK_WHITESPACE)
        tline = tline->next;
    if (!tline || tline->type != TOK_PREPROC_ID ||
        (tline->text[1]=='%' || tline->text[1]=='$' || tline->text[1]=='!'))
        return 0;

    i = -1;
    j = sizeof(directives)/sizeof(*directives);
    while (j-i > 1) {
        k = (j+i) / 2;
        m = nasm_stricmp(tline->text, directives[k]);
        if (m == 0) {
            i = k;
            j = -2;
            break;
        } else if (m < 0) {
            j = k;
        } else
            i = k;
    }

    /*
     * If we're in a non-emitting branch of a condition construct,
     * we should ignore all directives except for condition
     * directives.
     */
    if (istk->conds && !emitting(istk->conds->state) &&
        i != PP_IFCTX && i != PP_IFDEF && i != PP_IFNCTX && i != PP_IFNDEF &&
        i!=PP_ELIFCTX && i!=PP_ELIFDEF && i!=PP_ELIFNCTX && i!=PP_ELIFNDEF &&
        i != PP_ELSE && i != PP_ENDIF)
        return 0;

    /*
     * If we're defining a macro, we should ignore all directives
     * except for %macro/%imacro (which generate an error) and
     * %endm/%endmacro.
     */
    if (defining && i != PP_MACRO && i != PP_IMACRO &&
        i != PP_ENDMACRO && i != PP_ENDM)
        return 0;

    if (j != -2) {
        error(ERR_NONFATAL|ERR_OFFBY1, "unknown preprocessor directive `%s'",
              tline->text);
        return 0;                      /* didn't get it */
    }

    switch (i) {

      case PP_CLEAR:
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%clear' ignored");
        for (j=0; j<NHASH; j++) {
            while (mmacros[j]) {
                MMacro *m = mmacros[j];
                mmacros[j] = mmacros[j]->next;
                nasm_free (m->name);
                free_tlist (m->dlist);
                free_llist (m->expansion);
                nasm_free (m);
            }
            while (smacros[j]) {
                SMacro *s = smacros[j];
                smacros[j] = smacros[j]->next;
                nasm_free (s->name);
                free_tlist (s->expansion);
                nasm_free (s);
            }
        }
        return 3;

      case PP_INCLUDE:
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || (tline->type != TOK_STRING &&
                       tline->type != TOK_INTERNAL_STRING)) {
            error(ERR_NONFATAL|ERR_OFFBY1, "`%%include' expects a file name");
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%include' ignored");
        if (tline->type != TOK_INTERNAL_STRING) {
            p = tline->text+1;         /* point past the quote to the name */
            p[strlen(p)-1] = '\0';     /* remove the trailing quote */
        } else
            p = tline->text;           /* internal_string is easier */
        inc = nasm_malloc(sizeof(Include));
        inc->next = istk;
        inc->conds = NULL;
        inc->fp = inc_fopen(p);
        inc->fname = nasm_strdup(p);
        inc->lineno = inc->lineinc = 1;
        inc->expansion = NULL;
        istk = inc;
        list->uplevel (LIST_INCLUDE);
        return 5;

      case PP_PUSH:
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_ID) {
            error(ERR_NONFATAL|ERR_OFFBY1,
                  "`%%push' expects a context identifier");
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%push' ignored");
        ctx = nasm_malloc(sizeof(Context));
        ctx->next = cstk;
        ctx->localmac = NULL;
        ctx->name = nasm_strdup(tline->text);
        ctx->number = unique++;
        cstk = ctx;
        break;

      case PP_REPL:
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_ID) {
            error(ERR_NONFATAL|ERR_OFFBY1,
                  "`%%repl' expects a context identifier");
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%repl' ignored");
        if (!cstk)
            error(ERR_NONFATAL|ERR_OFFBY1,
                  "`%%repl': context stack is empty");
        else {
            nasm_free (cstk->name);
            cstk->name = nasm_strdup(tline->text);
        }
        break;

      case PP_POP:
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%pop' ignored");
        if (!cstk)
            error(ERR_NONFATAL|ERR_OFFBY1,
                  "`%%pop': context stack is already empty");
        else
            ctx_pop();
        break;

      case PP_ERROR:
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_STRING) {
            error(ERR_NONFATAL|ERR_OFFBY1,
                  "`%%error' expects an error string");
            return 3;                  /* but we did _something_ */
        }
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%error' ignored");
        p = tline->text+1;             /* point past the quote to the name */
        p[strlen(p)-1] = '\0';         /* remove the trailing quote */
        error(ERR_NONFATAL|ERR_OFFBY1, "user error: %s", p);
        break;

      case PP_IFCTX:
      case PP_IFNCTX:
        tline = tline->next;
        if (istk->conds && !emitting(istk->conds->state))
            j = COND_NEVER;
        else {
            j = FALSE;                 /* have we matched yet? */
            if (!cstk)
                error(ERR_FATAL|ERR_OFFBY1,
                      "`%%if%sctx': context stack is empty",
                      (i==PP_IFNCTX ? "n" : ""));
            else while (tline) {
                if (tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline || tline->type != TOK_ID) {
                    error(ERR_NONFATAL|ERR_OFFBY1,
                          "`%%ifctx' expects context identifiers");
                    return 3;          /* but we did _something_ */
                }
                if (!nasm_stricmp(tline->text, cstk->name))
                    j = TRUE;
                tline = tline->next;
            }
            if (i == PP_IFNCTX)
                j = !j;
            j = (j ? COND_IF_TRUE : COND_IF_FALSE);
        }
        cond = nasm_malloc(sizeof(Cond));
        cond->next = istk->conds;
        cond->state = j;
        istk->conds = cond;
        return 1;

      case PP_ELIFCTX:
      case PP_ELIFNCTX:
        tline = tline->next;
        if (!istk->conds)
            error(ERR_FATAL|ERR_OFFBY1, "`%%elif%sctx': no matching `%%if'",
                  (i==PP_ELIFNCTX ? "n" : ""));
        if (emitting(istk->conds->state) || istk->conds->state == COND_NEVER)
            istk->conds->state = COND_NEVER;
        else {
            j = FALSE;                 /* have we matched yet? */
            if (!cstk)
                error(ERR_FATAL|ERR_OFFBY1,
                      "`%%elif%sctx': context stack is empty",
                      (i==PP_ELIFNCTX ? "n" : ""));
            else while (tline) {
                if (tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline || tline->type != TOK_ID) {
                    error(ERR_NONFATAL|ERR_OFFBY1,
                          "`%%elif%sctx' expects context identifiers",
                          (i==PP_ELIFNCTX ? "n" : ""));
                    return 3;          /* but we did _something_ */
                }
                if (!nasm_stricmp(tline->text, cstk->name))
                    j = TRUE;
                tline = tline->next;
            }
            if (i == PP_ELIFNCTX)
                j = !j;
            istk->conds->state = (j ? COND_IF_TRUE : COND_IF_FALSE);
        }
        return 1;

      case PP_IFDEF:
      case PP_IFNDEF:
        tline = tline->next;
        if (istk->conds && !emitting(istk->conds->state))
            j = COND_NEVER;
        else {
            j = FALSE;                 /* have we matched yet? */
            while (tline) {
                if (tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline || (tline->type != TOK_ID &&
                               (tline->type != TOK_PREPROC_ID ||
                                tline->text[1] != '$'))) {
                    error(ERR_NONFATAL|ERR_OFFBY1,
                          "`%%if%sdef' expects macro identifiers",
                          (i==PP_ELIFNDEF ? "n" : ""));
                    return 3;          /* but we did _something_ */
                }
                if (smacro_defined(tline->text, 0, NULL))
                    j = TRUE;
                tline = tline->next;
            }
            if (i == PP_IFNDEF)
                j = !j;
            j = (j ? COND_IF_TRUE : COND_IF_FALSE);
        }
        cond = nasm_malloc(sizeof(Cond));
        cond->next = istk->conds;
        cond->state = j;
        istk->conds = cond;
        return 1;

      case PP_ELIFDEF:
      case PP_ELIFNDEF:
        tline = tline->next;
        if (!istk->conds)
            error(ERR_FATAL|ERR_OFFBY1, "`%%elif%sctx': no matching `%%if'",
                  (i==PP_ELIFNCTX ? "n" : ""));
        if (emitting(istk->conds->state) || istk->conds->state == COND_NEVER)
            istk->conds->state = COND_NEVER;
        else {
            j = FALSE;                 /* have we matched yet? */
            while (tline) {
                if (tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline || (tline->type != TOK_ID &&
                               (tline->type != TOK_PREPROC_ID ||
                                tline->text[1] != '$'))) {
                    error(ERR_NONFATAL|ERR_OFFBY1,
                          "`%%elif%sdef' expects macro identifiers",
                          (i==PP_ELIFNDEF ? "n" : ""));
                    return 3;          /* but we did _something_ */
                }
                if (smacro_defined(tline->text, 0, NULL))
                    j = TRUE;
                tline = tline->next;
            }
            if (i == PP_ELIFNDEF)
                j = !j;
            istk->conds->state = (j ? COND_IF_TRUE : COND_IF_FALSE);
        }
        return 1;

      case PP_ELSE:
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%else' ignored");
        if (!istk->conds)
            error(ERR_FATAL|ERR_OFFBY1,
                  "`%%else': no matching `%%if'");
        if (emitting(istk->conds->state) || istk->conds->state == COND_NEVER)
            istk->conds->state = COND_ELSE_FALSE;
        else
            istk->conds->state = COND_ELSE_TRUE;
        return 1;

      case PP_ENDIF:
        if (tline->next)
            error(ERR_WARNING|ERR_OFFBY1,
                  "trailing garbage after `%%endif' ignored");
        if (!istk->conds)
            error(ERR_FATAL|ERR_OFFBY1,
                  "`%%endif': no matching `%%if'");
        cond = istk->conds;
        istk->conds = cond->next;
        nasm_free (cond);
        return 5;

      case PP_MACRO:
      case PP_IMACRO:
        if (defining)
            error (ERR_FATAL|ERR_OFFBY1,
                   "`%%%smacro': already defining a macro",
                   (i == PP_IMACRO ? "i" : ""));
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_ID) {
            error (ERR_NONFATAL|ERR_OFFBY1,
                   "`%%%smacro' expects a macro name",
                   (i == PP_IMACRO ? "i" : ""));
            return 3;
        }
        defining = nasm_malloc(sizeof(MMacro));
        defining->name = nasm_strdup(tline->text);
        defining->casesense = (i == PP_MACRO);
        defining->plus = FALSE;
        defining->nolist = FALSE;
        defining->in_progress = FALSE;
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_NUMBER) {
            error (ERR_NONFATAL|ERR_OFFBY1,
                   "`%%%smacro' expects a parameter count",
                   (i == PP_IMACRO ? "i" : ""));
            defining->nparam_min = defining->nparam_max = 0;
        } else {
            defining->nparam_min = defining->nparam_max =
                readnum(tline->text, &j);
            if (j)
                error (ERR_NONFATAL|ERR_OFFBY1,
                       "unable to parse parameter count `%s'", tline->text);
        }
        if (tline && tline->next && tline->next->type == TOK_OTHER &&
            !strcmp(tline->next->text, "-")) {
            tline = tline->next->next;
            if (!tline || tline->type != TOK_NUMBER)
                error (ERR_NONFATAL|ERR_OFFBY1,
                       "`%%%smacro' expects a parameter count after `-'",
                       (i == PP_IMACRO ? "i" : ""));
            else {
                defining->nparam_max = readnum(tline->text, &j);
                if (j)
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "unable to parse parameter count `%s'",
                           tline->text);
                if (defining->nparam_min > defining->nparam_max)
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "minimum parameter count exceeds maximum");
            }
        }
        if (tline && tline->next && tline->next->type == TOK_OTHER &&
            !strcmp(tline->next->text, "+")) {
            tline = tline->next;
            defining->plus = TRUE;
        }
        if (tline && tline->next && tline->next->type == TOK_ID &&
            !nasm_stricmp(tline->next->text, ".nolist")) {
            tline = tline->next;
            defining->nolist = TRUE;
        }
        mmac = mmacros[hash(defining->name)];
        while (mmac) {
            if (!strcmp(mmac->name, defining->name) &&
                (mmac->nparam_min<=defining->nparam_max || defining->plus) &&
                (defining->nparam_min<=mmac->nparam_max || mmac->plus)) {
                error (ERR_WARNING|ERR_OFFBY1,
                       "redefining multi-line macro `%s'", defining->name);
                break;
            }
            mmac = mmac->next;
        }
        /*
         * Handle default parameters.
         */
        if (tline && tline->next) {
            int np, want_np;

            defining->dlist = tline->next;
            tline->next = NULL;
            count_mmac_params (defining->dlist, &np, &defining->defaults);
            want_np = defining->nparam_max - defining->nparam_min;
            defining->defaults = nasm_realloc (defining->defaults,
                                               want_np*sizeof(Token *));
            while (np < want_np)
                defining->defaults[np++] = NULL;
        } else {
            defining->dlist = NULL;
            defining->defaults = NULL;
        }
        defining->expansion = NULL;
        return 1;

      case PP_ENDM:
      case PP_ENDMACRO:
        if (!defining) {
            error (ERR_NONFATAL|ERR_OFFBY1, "`%s': not defining a macro",
                   tline->text);
            return 3;
        }
        k = hash(defining->name);
        defining->next = mmacros[k];
        mmacros[k] = defining;
        defining = NULL;
        return 5;

      case PP_DEFINE:
      case PP_IDEFINE:
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || (tline->type != TOK_ID &&
                       (tline->type != TOK_PREPROC_ID ||
                        tline->text[1] != '$'))) {
            error (ERR_NONFATAL|ERR_OFFBY1,
                   "`%%%sdefine' expects a macro identifier",
                   (i == PP_IDEFINE ? "i" : ""));
            return 3;
        }
        mname = tline->text;
        if (tline->type == TOK_ID) {
            p = tline->text;
            smhead = &smacros[hash(mname)];
        } else {
            ctx = get_ctx (tline->text);
            if (ctx == NULL)
                return 3;
            else {
                p = tline->text+1;
                p += strspn(p, "$");
                smhead = &ctx->localmac;
            }
        }
        last = tline;
        param_start = tline = tline->next;
        nparam = 0;
        if (tline && tline->type == TOK_OTHER && !strcmp(tline->text, "(")) {
            /*
             * This macro has parameters.
             */

            tline = tline->next;
            while (1) {
                if (tline && tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline) {
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "parameter identifier expected");
                    return 3;
                }
                if (tline->type != TOK_ID) {
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "`%s': parameter identifier expected",
                           tline->text);
                    return 3;
                }
                tline->type = TOK_SMAC_PARAM + nparam++;
                tline = tline->next;
                if (tline && tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (tline && tline->type == TOK_OTHER &&
                    !strcmp(tline->text, ",")) {
                    tline = tline->next;
                    continue;
                }
                if (!tline || tline->type != TOK_OTHER ||
                    strcmp(tline->text, ")")) {
                    error (ERR_NONFATAL|ERR_OFFBY1,
                           "`)' expected to terminate macro template");
                    return 3;
                }
                break;
            }
            last = tline;
            tline = tline->next;
        }
        if (tline && tline->type == TOK_WHITESPACE)
            last = tline, tline = tline->next;
        macro_start = NULL;
        last->next = NULL;
        t = tline;
        while (t) {
            if (t->type == TOK_ID) {
                for (tt = param_start; tt; tt = tt->next)
                    if (tt->type >= TOK_SMAC_PARAM &&
                        !strcmp(tt->text, t->text))
                        t->type = tt->type;
            }
            tt = t->next;
            t->next = macro_start;
            macro_start = t;
            t = tt;
        }
        /*
         * Good. We now have a macro name, a parameter count, and a
         * token list (in reverse order) for an expansion. We ought
         * to be OK just to create an SMacro, store it, and let
         * free_tlist have the rest of the line (which we have
         * carefully re-terminated after chopping off the expansion
         * from the end).
         */
        if (smacro_defined (mname, nparam, &smac)) {
            if (!smac)
                error (ERR_WARNING|ERR_OFFBY1,
                       "single-line macro `%s' defined both with and"
                       " without parameters", mname);
            else {
                /*
                 * We're redefining, so we have to take over an
                 * existing SMacro structure. This means freeing
                 * what was already in it.
                 */
                nasm_free (smac->name);
                free_tlist (smac->expansion);
            }
        } else {
            smac = nasm_malloc(sizeof(SMacro));
            smac->next = *smhead;
            *smhead = smac;
        }
        smac->name = nasm_strdup(p);
        smac->casesense = (i == PP_DEFINE);
        smac->nparam = nparam;
        smac->expansion = macro_start;
        smac->in_progress = FALSE;
        return 3;

      case PP_LINE:
        /*
         * Syntax is `%line nnn[+mmm] [filename]'
         */
        tline = tline->next;
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        if (!tline || tline->type != TOK_NUMBER) {
            error (ERR_NONFATAL|ERR_OFFBY1, "`%%line' expects line number");
            return 3;
        }
        k = readnum(tline->text, &j);
        m = 1;
        tline = tline->next;
        if (tline && tline->type == TOK_OTHER && !strcmp(tline->text, "+")) {
            tline = tline->next;
            if (!tline || tline->type != TOK_NUMBER) {
                error (ERR_NONFATAL|ERR_OFFBY1,
                       "`%%line' expects line increment");
                return 3;
            }
            m = readnum(tline->text, &j);
            tline = tline->next;
        }
        if (tline && tline->type == TOK_WHITESPACE)
            tline = tline->next;
        istk->lineno = k;
        istk->lineinc = m;
        if (tline) {
            char *s = detoken(tline);
            nasm_free (istk->fname);
            istk->fname = s;
        }
        return 5;

      default:
        error(ERR_FATAL|ERR_OFFBY1,
              "preprocessor directive `%s' not yet implemented",
              directives[k]);
        break;
    }
    return 3;
}

/*
 * Expand all single-line macro calls made in the given line.
 * Return the expanded version of the line. The original is deemed
 * to be destroyed in the process. (In reality we'll just move
 * Tokens from input to output a lot of the time, rather than
 * actually bothering to destroy and replicate.)
 */
static Token *expand_smacro (Token *tline) {
    Token *t, *tt, *mstart, **tail, *thead;
    SMacro *head, *m;
    Token **params;
    int *paramsize;
    int nparam, sparam, brackets;
    char *p;

    tail = &thead;
    thead = NULL;

    while (tline) {
        while (tline && tline->type != TOK_ID &&
               (tline->type != TOK_PREPROC_ID || tline->text[1] != '$')) {
            if (tline->type == TOK_SMAC_END) {
                tline->mac->in_progress = FALSE;
                t = tline;
                tline = tline->next;
                nasm_free (t);
            } else {
                t = *tail = tline;
                tline = tline->next;
                t->mac = NULL;
                t->next = NULL;
                tail = &t->next;
                if (t->type == TOK_PS_OTHER) {
                    /*
                     * If we see a PS_OTHER, we must at the very
                     * least restore its correct token type. We
                     * should also check for a %$ token, since this
                     * is the point at which we expand context-
                     * local labels.
                     */
                    t->type = TOK_ID;
                    if (t->text[0] == '%' && t->text[1] == '$') {
                        Context *c = get_ctx (t->text);
                        char *p, *q, buffer[40];

                        if (c) {
                            q = t->text+1;
                            q += strspn(q, "$");
                            sprintf(buffer, "..@%lu.", c->number);
                            p = nasm_malloc (strlen(buffer)+strlen(q)+1);
                            strcpy (p, buffer);
                            strcat (p, q);
                            nasm_free (t->text);
                            t->text = p;
                        }
                    }
                }
            }
        }
        if (!tline)
            break;
        /*
         * We've hit an identifier. As in is_mmacro below, we first
         * check whether the identifier is a single-line macro at
         * all, then think about checking for parameters if
         * necessary.
         */
        if (tline->type == TOK_ID) {
            head = smacros[hash(tline->text)];
            p = tline->text;
        } else {
            Context *ctx = get_ctx (tline->text);
            if (ctx) {
                p = tline->text+1;
                p += strspn(p, "$");
                head = ctx->localmac;
            } else {
                tline->type = TOK_OTHER; /* so it will get copied above */
                continue;               
            }
        }
        for (m = head; m; m = m->next)
            if (!mstrcmp(m->name, p, m->casesense))
                break;
        if (!m || m->in_progress) {
            /*
             * Either we didn't find a macro, so this can't be a
             * macro call, or we found a macro which was already in
             * progress, in which case we don't _treat_ this as a
             * macro call. Copy it through and ignore it.
             */
            tline->type = TOK_PS_OTHER;   /* so it will get copied above */
            continue;
        }
        mstart = tline;
        if (m->nparam == 0) {
            /*
             * Simple case: the macro is parameterless. Discard the
             * one token that the macro call took, and push the
             * expansion back on the to-do stack.
             */
            params = NULL;
            paramsize = NULL;
        } else {
            /*
             * Complicated case: at least one macro with this name
             * exists and takes parameters. We must find the
             * parameters in the call, count them, find the SMacro
             * that corresponds to that form of the macro call, and
             * substitute for the parameters when we expand. What a
             * pain.
             */
            nparam = sparam = 0;
            params = NULL;
            paramsize = NULL;
            tline = tline->next;
            if (tline && tline->type == TOK_WHITESPACE)
                tline = tline->next;
            if (!tline || tline->type != TOK_OTHER ||
                strcmp(tline->text, "(")) {
                /*
                 * This macro wasn't called with parameters: ignore
                 * the call. (Behaviour borrowed from gnu cpp.)
                 */
                tline = mstart;
                tline->type = TOK_PS_OTHER;
                continue;
            }
            tline = tline->next;
            while (1) {
                if (tline && tline->type == TOK_WHITESPACE)
                    tline = tline->next;
                if (!tline) {
                    error(ERR_NONFATAL|ERR_OFFBY1,
                          "macro call expects terminating `)'");
                    break;
                }
                if (nparam >= sparam) {
                    sparam += PARAM_DELTA;
                    params = nasm_realloc (params, sparam*sizeof(Token *));
                    paramsize = nasm_realloc (paramsize, sparam*sizeof(int));
                }
                params[nparam] = tline;
                paramsize[nparam] = 0;
                brackets = 0;
                if (tline && tline->type == TOK_OTHER &&
                    !strcmp(tline->text, "{")) {
                    params[nparam] = tline = tline->next;
                    while (tline && (brackets > 0 ||
                                     tline->type != TOK_OTHER ||
                                     strcmp(tline->text, "}"))) {
                        tline = tline->next;
                        paramsize[nparam]++;
                    }
                    tline = tline->next;
                    if (tline && tline->type == TOK_WHITESPACE)
                        tline = tline->next;
                    if (tline && (tline->type != TOK_OTHER ||
                                  (strcmp(tline->text, ")") &&
                                   strcmp(tline->text, ",")))) {
                        error (ERR_NONFATAL|ERR_OFFBY1, "braces do not "
                               "enclose all of macro parameter");
                    }
                    if (tline && tline->type == TOK_OTHER &&
                        !strcmp(tline->text, ","))
                        tline = tline->next;
                } else {
                    while (tline && (brackets > 0 ||
                                     tline->type != TOK_OTHER ||
                                     (strcmp(tline->text, ",") &&
                                      strcmp(tline->text, ")")))) {
                        if (tline->type == TOK_OTHER && !tline->text[1])
                            brackets += (tline->text[0] == '(' ? 1 :
                                         tline->text[0] == ')' ? -1 : 0);
                        tline = tline->next;
                        paramsize[nparam]++;
                    }
                }
                nparam++;
                if (tline && !strcmp(tline->text, ")"))
                    break;
                if (tline && !strcmp(tline->text, ","))
                    tline = tline->next;
            }
            while (m && m->nparam != nparam) {
                while ( (m = m->next) )
                    if (!strcmp(m->name, mstart->text))
                        break;
            }
            if (!m) {
                error (ERR_WARNING|ERR_OFFBY1|ERR_WARN_MNP,
                       "macro `%s' exists, but not taking %d parameters",
                       mstart->text, nparam);
                nasm_free (params);
                nasm_free (paramsize);
                tline = mstart;
                tline->type = TOK_PS_OTHER;
                continue;
            }
        }
        /*
         * Expand the macro: we are placed on the last token of the
         * call, so that we can easily split the call from the
         * following tokens. We also start by pushing an SMAC_END
         * token for the cycle removal.
         */
        t = tline;
        tline = tline->next;
        t->next = NULL;
        tt = nasm_malloc(sizeof(Token));
        tt->type = TOK_SMAC_END;
        tt->text = NULL;
        tt->mac = m;
        m->in_progress = TRUE;
        tt->next = tline;
        tline = tt;
        for (t = m->expansion; t; t = t->next) {
            if (t->type >= TOK_SMAC_PARAM) {
                Token *pcopy = tline, **ptail = &pcopy;
                Token *ttt, *pt;
                int i;
                
                ttt = params[t->type - TOK_SMAC_PARAM];
                for (i=0; i<paramsize[t->type-TOK_SMAC_PARAM]; i++) {
                    pt = *ptail = nasm_malloc(sizeof(Token));
                    pt->next = tline;
                    ptail = &pt->next;
                    pt->text = nasm_strdup(ttt->text);
                    pt->type = ttt->type;
                    pt->mac = NULL;
                    ttt = ttt->next;
                }
                tline = pcopy;
            } else {
                tt = nasm_malloc(sizeof(Token));
                tt->type = t->type;
                tt->text = nasm_strdup(t->text);
                tt->mac = NULL;
                tt->next = tline;
                tline = tt;
            }
        }

        /*
         * Having done that, get rid of the macro call, and clean
         * up the parameters.
         */
        nasm_free (params);
        nasm_free (paramsize);
        free_tlist (mstart);
    }

    return thead;
}

/*
 * Ensure that a macro parameter contains a condition code and
 * nothing else. Return the condition code index if so, or -1
 * otherwise.
 */
static int find_cc (Token *t) {
    Token *tt;
    int i, j, k, m;

    if (t && t->type == TOK_WHITESPACE)
        t = t->next;
    if (t->type != TOK_ID)
        return -1;
    tt = t->next;
    if (tt && tt->type == TOK_WHITESPACE)
        tt = tt->next;
    if (tt && (tt->type != TOK_OTHER || strcmp(tt->text, ",")))
        return -1;

    i = -1;
    j = sizeof(conditions)/sizeof(*conditions);
    while (j-i > 1) {
        k = (j+i) / 2;
        m = nasm_stricmp(t->text, conditions[k]);
        if (m == 0) {
            i = k;
            j = -2;
            break;
        } else if (m < 0) {
            j = k;
        } else
            i = k;
    }
    if (j != -2)
        return -1;
    return i;
}

/*
 * Determine whether the given line constitutes a multi-line macro
 * call, and return the MMacro structure called if so. Doesn't have
 * to check for an initial label - that's taken care of in
 * expand_mmacro - but must check numbers of parameters. Guaranteed
 * to be called with tline->type == TOK_ID, so the putative macro
 * name is easy to find.
 */
static MMacro *is_mmacro (Token *tline, Token ***params_array) {
    MMacro *head, *m;
    Token **params;
    int nparam;

    head = mmacros[hash(tline->text)];

    /*
     * Efficiency: first we see if any macro exists with the given
     * name. If not, we can return NULL immediately. _Then_ we
     * count the parameters, and then we look further along the
     * list if necessary to find the proper MMacro.
     */
    for (m = head; m; m = m->next)
        if (!mstrcmp(m->name, tline->text, m->casesense))
            break;
    if (!m)
        return NULL;

    /*
     * OK, we have a potential macro. Count and demarcate the
     * parameters.
     */
    count_mmac_params (tline->next, &nparam, &params);

    /*
     * So we know how many parameters we've got. Find the MMacro
     * structure that handles this number.
     */
    while (m) {
        if (m->nparam_min <= nparam && (m->plus || nparam <= m->nparam_max)) {
            /*
             * This one is right. Just check if cycle removal
             * prohibits us using it before we actually celebrate...
             */
            if (m->in_progress) {
                error (ERR_NONFATAL|ERR_OFFBY1,
                       "self-reference in multi-line macro `%s'",
                       m->name);
                nasm_free (params);
                return NULL;
            }
            /*
             * It's right, and we can use it. Add its default
             * parameters to the end of our list if necessary.
             */
            params = nasm_realloc (params, (m->nparam_max+1)*sizeof(*params));
            if (m->defaults) {
                while (nparam < m->nparam_max) {
                    params[nparam] = m->defaults[nparam - m->nparam_min];
                    nparam++;
                }
            } else {
                while (nparam < m->nparam_max) {
                    params[nparam] = NULL;
                    nparam++;
                }
            }
            /*
             * Then terminate the parameter list, and leave.
             */
            params[m->nparam_max] = NULL;
            *params_array = params;
            return m;
        }
        /*
         * This one wasn't right: look for the next one with the
         * same name.
         */
        for (m = m->next; m; m = m->next)
            if (!mstrcmp(m->name, tline->text, m->casesense))
                break;
    }

    /*
     * After all that, we didn't find one with the right number of
     * parameters. Issue a warning, and fail to expand the macro.
     */
    error (ERR_WARNING|ERR_OFFBY1|ERR_WARN_MNP,
           "macro `%s' exists, but not taking %d parameters",
           tline->text, nparam);
    nasm_free (params);
    return NULL;
}

/*
 * Expand the multi-line macro call made by the given line, if
 * there is one to be expanded. If there is, push the expansion on
 * istk->expansion and return 1 or 2, as according to whether a
 * line sync is needed (2 if it is). Otherwise return 0.
 */
static int expand_mmacro (Token *tline) {
    Token *label = NULL, **params, *t, *tt, *ttt, *last = NULL;
    MMacro *m = NULL;
    Line *l, *ll;
    int i, n, nparam, *paramlen;
    int need_sync = FALSE;

    t = tline;
    if (t && t->type == TOK_WHITESPACE)
        t = t->next;
    if (t && t->type == TOK_ID) {
        m = is_mmacro (t, &params);
        if (!m) {
            /*
             * We have an id which isn't a macro call. We'll assume
             * it might be a label; we'll also check to see if a
             * colon follows it. Then, if there's another id after
             * that lot, we'll check it again for macro-hood.
             */
            last = t, t = t->next;
            if (t && t->type == TOK_WHITESPACE)
                last = t, t = t->next;
            if (t && t->type == TOK_OTHER && !strcmp(t->text, ":"))
                last = t, t = t->next;
            if (t && t->type == TOK_WHITESPACE)
                last = t, t = t->next;
            if (t && t->type == TOK_ID) {
                m = is_mmacro(t, &params);
                if (m) {
                    last->next = NULL;
                    label = tline;
                    tline = t;
                }
            }
        }       
    }
    if (!m)
        return 0;

    /*
     * If we're not already inside another macro expansion, we'd
     * better push a line synchronisation to ensure we stay put on
     * line numbering.
     */
    if (!istk->expansion)
        need_sync = TRUE;

    /*
     * Fix up the parameters: this involves stripping leading and
     * trailing whitespace, then stripping braces if they are
     * present.
     */
    for (nparam = 0; params[nparam]; nparam++);
    paramlen = nparam ? nasm_malloc(nparam*sizeof(*paramlen)) : NULL;

    for (i = 0; params[i]; i++) {
        int brace = FALSE;
        int comma = (!m->plus || i < nparam-1);

        t = params[i];
        if (t && t->type == TOK_WHITESPACE)
            t = t->next;
        if (t && t->type == TOK_OTHER && !strcmp(t->text, "{"))
            t = t->next, brace = TRUE, comma = FALSE;
        params[i] = t;
        paramlen[i] = 0;
        while (t) {
            if (!t)                    /* end of param because EOL */
                break;
            if (comma && t->type == TOK_OTHER && !strcmp(t->text, ","))
                break;                 /* ... because we have hit a comma */
            if (comma && t->type == TOK_WHITESPACE &&
                t->next->type == TOK_OTHER && !strcmp(t->next->text, ","))
                break;                 /* ... or a space then a comma */
            if (brace && t->type == TOK_OTHER && !strcmp(t->text, "}"))
                break;                 /* ... or a brace */
            t = t->next;
            paramlen[i]++;
        }
    }

    /*
     * OK, we have a MMacro structure together with a set of
     * parameters. We must now go through the expansion and push
     * _copies_ of each Line on to istk->expansion, having first
     * substituted for most % tokens (%1, %+1, %-1, %%foo). Note
     * that %$bar, %$$baz, %$$$quux, and so on, do not get
     * substituted here but rather have to wait until the
     * single-line macro substitution process. This is because they
     * don't just crop up in macro definitions, but can appear
     * anywhere they like.
     *
     * First, push an end marker on to istk->expansion, and mark
     * this macro as in progress.
     */
    ll = nasm_malloc(sizeof(Line));
    ll->next = istk->expansion;
    ll->finishes = m;
    ll->first = NULL;
    istk->expansion = ll;
    m->in_progress = TRUE;
    for (l = m->expansion; l; l = l->next) {
        Token **tail;

        ll = nasm_malloc(sizeof(Line));
        ll->next = istk->expansion;
        ll->finishes = NULL;
        ll->first = NULL;
        tail = &ll->first;

        for (t = l->first; t; t = t->next) {
            char *text;
            int type = 0, cc;          /* type = 0 to placate optimisers */
            char tmpbuf[30];

            if (t->type == TOK_PREPROC_ID &&
                (t->text[1] == '+' || t->text[1] == '-' ||
                 t->text[1] == '%' ||
                 (t->text[1] >= '0' && t->text[1] <= '9'))) {
                /*
                 * We have to make a substitution of one of the
                 * forms %1, %-1, %+1, %%foo.
                 */
                switch (t->text[1]) {
                  case '%':
                    type = TOK_ID;
                    sprintf(tmpbuf, "..@%lu.", unique);
                    text = nasm_malloc(strlen(tmpbuf)+strlen(t->text+2)+1);
                    strcpy(text, tmpbuf);
                    strcat(text, t->text+2);
                    break;
                  case '-':
                    n = atoi(t->text+2)-1;
                    tt = params[n];
                    cc = find_cc (tt);
                    if (cc == -1) {
                        error (ERR_NONFATAL|ERR_OFFBY1,
                               "macro parameter %d is not a condition code",
                               n+1);
                        text = NULL;
                    } else {
                        type = TOK_ID;
                        if (inverse_ccs[cc] == -1) {
                            error (ERR_NONFATAL|ERR_OFFBY1,
                                   "condition code `%s' is not invertible",
                                   conditions[cc]);
                            text = NULL;
                        } else
                            text = nasm_strdup(conditions[inverse_ccs[cc]]);
                    }
                    break;
                  case '+':
                    n = atoi(t->text+2)-1;
                    tt = params[n];
                    cc = find_cc (tt);
                    if (cc == -1) {
                        error (ERR_NONFATAL|ERR_OFFBY1,
                               "macro parameter %d is not a condition code",
                               n+1);
                        text = NULL;
                    } else {
                        type = TOK_ID;
                        text = nasm_strdup(conditions[cc]);
                    }
                    break;
                  default:
                    n = atoi(t->text+1)-1;
                    if (n < nparam) {
                        ttt = params[n];
                        for (i=0; i<paramlen[n]; i++) {
                            tt = *tail = nasm_malloc(sizeof(Token));
                            tt->next = NULL;
                            tail = &tt->next;
                            tt->type = ttt->type;
                            tt->text = nasm_strdup(ttt->text);
                            tt->mac = NULL;
                            ttt = ttt->next;
                        }
                    }
                    text = NULL;       /* we've done it here */
                    break;
                }
            } else {
                type = t->type;
                text = nasm_strdup(t->text);
            }

            if (text) {
                tt = *tail = nasm_malloc(sizeof(Token));
                tt->next = NULL;
                tail = &tt->next;
                tt->type = type;
                tt->text = text;
                tt->mac = NULL;
            }
        }

        istk->expansion = ll;

    }

    /*
     * If we had a label, push it on the front of the first line of
     * the macro expansion.
     */
    if (label) {
        last->next = istk->expansion->first;
        istk->expansion->first = label;
    }

    /*
     * Clean up.
     */
    unique++;
    nasm_free (paramlen);
    nasm_free (params);
    free_tlist (tline);

    list->uplevel (m->nolist ? LIST_MACRO_NOLIST : LIST_MACRO);

    return need_sync ? 2 : 1;
}

static void pp_reset (char *file, efunc errfunc, ListGen *listgen) {
    int h;

    error = errfunc;
    cstk = NULL;
    linesync = outline = NULL;
    istk = nasm_malloc(sizeof(Include));
    istk->next = NULL;
    istk->conds = NULL;
    istk->expansion = NULL;
    istk->fp = fopen(file, "r");
    istk->fname = nasm_strdup(file);
    istk->lineno = istk->lineinc = 1;
    if (!istk->fp)
        error (ERR_FATAL|ERR_NOFILE, "unable to open input file `%s'", file);
    defining = NULL;
    for (h=0; h<NHASH; h++) {
        mmacros[h] = NULL;
        smacros[h] = NULL;
    }
    unique = 0;
    stdmacpos = stdmac;
    list = listgen;
}

static char *pp_getline (void) {
    char *line;
    Token *tline;
    int ret;

    if (outline) {
        line = outline;
        outline = NULL;
        return line;
    }

    while (1) {
        /*
         * Fetch a tokenised line, either from the macro-expansion
         * buffer or from the input file.
         */
        tline = NULL;
        while (istk->expansion && istk->expansion->finishes) {
            Line *l = istk->expansion;
            l->finishes->in_progress = FALSE;
            istk->expansion = l->next;
            nasm_free (l);
            list->downlevel (LIST_MACRO);
            if (!istk->expansion)
                line_sync();
        }
        if (istk->expansion) {
            char *p;
            Line *l = istk->expansion;
            tline = l->first;
            istk->expansion = l->next;
            nasm_free (l);
            p = detoken(tline);
            list->line (LIST_MACRO, p);
            nasm_free(p);
            if (!istk->expansion)
                line_sync();
        } else {
            line = read_line();
            while (!line) {
                /*
                 * The current file has ended; work down the istk
                 * until we find a file we can read from.
                 */
                Include *i;
                fclose(istk->fp);
                if (istk->conds)
                    error(ERR_FATAL, "expected `%%endif' before end of file");
                i = istk;
                istk = istk->next;
                list->downlevel (LIST_INCLUDE);
                nasm_free (i->fname);
                nasm_free (i);
                if (!istk)
                    return NULL;
                else
                    line_sync();
                line = read_line();
            }
            line = prepreproc(line);
            tline = tokenise(line);
            nasm_free (line);
        }

        /*
         * Check the line to see if it's a preprocessor directive.
         */
        ret = do_directive(tline);
        if (ret & 1) {
            free_tlist (tline);
            if (ret & 4)
                line_sync();
            if ((ret & 2) && !stdmacpos) {/* give a blank line to the output */
                outline = nasm_strdup("");
                break;
            }
            else
                continue;
        } else if (defining) {
            /*
             * We're defining a multi-line macro. We emit nothing
             * at all, not even a blank line (when we finish
             * defining the macro, we'll emit a line-number
             * directive so that we keep sync properly), and just
             * shove the tokenised line on to the macro definition.
             */
            Line *l = nasm_malloc(sizeof(Line));
            l->next = defining->expansion;
            l->first = tline;
            l->finishes = FALSE;
            defining->expansion = l;
            continue;
        } else if (istk->conds && !emitting(istk->conds->state)) {
            /*
             * We're in a non-emitting branch of a condition block.
             * Emit nothing at all, not even a blank line: when we
             * emerge from the condition we'll give a line-number
             * directive so we keep our place correctly.
             */
            free_tlist(tline);
            continue;
        } else {
            tline = expand_smacro(tline);
            ret = expand_mmacro(tline);
            if (!ret) {
                /*
                 * De-tokenise the line again, and emit it.
                 */
                line = detoken(tline);
                free_tlist (tline);
                outline = line;
                break;
            } else {
                if (ret == 2)
                    line_sync();
                continue;              /* expand_mmacro calls free_tlist */
            }
        }
    }

    /*
     * Once we're out of this loop, outline _must_ be non-NULL. The
     * only question is whether linesync is NULL or not.
     */
    if (linesync) {
        line = linesync;
        linesync = NULL;
    } else {
        line = outline;
        outline = NULL;
    }
    return line;
}

static void pp_cleanup (void) {
    int h;

    if (defining) {
        error (ERR_NONFATAL, "end of file while still defining macro `%s'",
               defining->name);
        nasm_free (defining->name);
        free_tlist (defining->dlist);
        free_llist (defining->expansion);
        nasm_free (defining);
    }
    nasm_free (linesync);              /* might just be necessary */
    nasm_free (outline);               /* really shouldn't be necessary */
    while (cstk)
        ctx_pop();
    for (h=0; h<NHASH; h++) {
        while (mmacros[h]) {
            MMacro *m = mmacros[h];
            mmacros[h] = mmacros[h]->next;
            nasm_free (m->name);
            free_tlist (m->dlist);
            free_llist (m->expansion);
            nasm_free (m);
        }
        while (smacros[h]) {
            SMacro *s = smacros[h];
            smacros[h] = smacros[h]->next;
            nasm_free (s->name);
            free_tlist (s->expansion);
            nasm_free (s);
        }
    }
    while (istk) {
        Include *i = istk;
        istk = istk->next;
        fclose(i->fp);
        nasm_free (i->fname);
        nasm_free (i);
    }
    while (cstk)
        ctx_pop();
}

void pp_include_path (char *path) {
    IncPath *i;

    i = nasm_malloc(sizeof(IncPath));
    i->path = nasm_strdup(path);
    i->next = ipath;

    ipath = i;
}

void pp_pre_include (char *fname) {
    Token *inc, *space, *name;
    Line *l;

    inc = nasm_malloc(sizeof(Token));
    inc->next = space = nasm_malloc(sizeof(Token));
    space->next = name = nasm_malloc(sizeof(Token));
    name->next = NULL;

    inc->type = TOK_PREPROC_ID;
    inc->text = nasm_strdup("%include");
    space->type = TOK_WHITESPACE;
    space->text = nasm_strdup(" ");
    name->type = TOK_INTERNAL_STRING;
    name->text = nasm_strdup(fname);

    inc->mac = space->mac = name->mac = NULL;

    l = nasm_malloc(sizeof(Line));
    l->next = predef;
    l->first = inc;
    l->finishes = FALSE;
    predef = l;
}

void pp_pre_define (char *definition) {
    Token *def, *space, *name;
    Line *l;
    char *equals;

    equals = strchr(definition, '=');

    def = nasm_malloc(sizeof(Token));
    def->next = space = nasm_malloc(sizeof(Token));
    if (equals)
        *equals = ' ';
    space->next = name = tokenise(definition);
    if (equals)
        *equals = '=';

    def->type = TOK_PREPROC_ID;
    def->text = nasm_strdup("%define");
    space->type = TOK_WHITESPACE;
    space->text = nasm_strdup(" ");

    def->mac = space->mac = NULL;

    l = nasm_malloc(sizeof(Line));
    l->next = predef;
    l->first = def;
    l->finishes = FALSE;
    predef = l;
}

Preproc nasmpp = {
    pp_reset,
    pp_getline,
    pp_cleanup
};