bunzip: small code shrink and consmetics

read_bunzip                                          276     283      +7
get_bits                                             184     162     -22
get_next_block                                      1833    1810     -23
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 7/-45)             Total: -38 bytes

diff --git a/archival/libunarchive/decompress_bunzip2.c b/archival/libunarchive/decompress_bunzip2.c
index 17b87e2..c1b1273 100644 (file)
--- a/archival/libunarchive/decompress_bunzip2.c
+++ b/archival/libunarchive/decompress_bunzip2.c
@@ -44,7 +44,7 @@
 #define RETVAL_LAST_BLOCK               (-1)
 #define RETVAL_NOT_BZIP_DATA            (-2)
 #define RETVAL_UNEXPECTED_INPUT_EOF     (-3)
-#define RETVAL_UNEXPECTED_OUTPUT_EOF    (-4)
+#define RETVAL_SHORT_WRITE              (-4)
 #define RETVAL_DATA_ERROR               (-5)
 #define RETVAL_OUT_OF_MEMORY            (-6)
 #define RETVAL_OBSOLETE_INPUT           (-7)
@@ -54,22 +54,27 @@
 
 /* This is what we know about each Huffman coding group */
 struct group_data {
-       /* We have an extra slot at the end of limit[] for a sentinal value. */
+       /* We have an extra slot at the end of limit[] for a sentinel value. */
        int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS];
        int minLen, maxLen;
 };
 
 /* Structure holding all the housekeeping data, including IO buffers and
-   memory that persists between calls to bunzip */
+ * memory that persists between calls to bunzip
+ * Found the most used member:
+ *  cat this_file.c | sed -e 's/"/ /g' -e "s/'/ /g" | xargs -n1 \
+ *  | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER
+ * and moved it (inbufBitCount) to offset 0.
+ */
 
 struct bunzip_data {
-       /* State for interrupting output loop */
-       int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
-
        /* I/O tracking data (file handles, buffers, positions, etc.) */
+       unsigned inbufBitCount, inbufBits;
        int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/;
        unsigned char *inbuf /*,*outbuf*/;
-       unsigned inbufBitCount, inbufBits;
+
+       /* State for interrupting output loop */
+       int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
 
        /* The CRC values stored in the block header and calculated from the data */
        uint32_t headerCRC, totalCRC, writeCRC;
@@ -80,7 +85,7 @@ struct bunzip_data {
        /* For I/O error handling */
        jmp_buf jmpbuf;
 
-       /* Big things go last (register-relative addressing can be larger for big offsets */
+       /* Big things go last (register-relative addressing can be larger for big offsets) */
        uint32_t crc32Table[256];
        unsigned char selectors[32768];                 /* nSelectors=15 bits */
        struct group_data groups[MAX_GROUPS];   /* Huffman coding tables */
@@ -91,7 +96,7 @@ struct bunzip_data {
 /* Return the next nnn bits of input.  All reads from the compressed input
    are done through this function.  All reads are big endian */
 
-static unsigned get_bits(bunzip_data *bd, char bits_wanted)
+static unsigned get_bits(bunzip_data *bd, int bits_wanted)
 {
        unsigned bits = 0;
 
@@ -121,7 +126,7 @@ static unsigned get_bits(bunzip_data *bd, char bits_wanted)
 
                /* Grab next 8 bits of input from buffer. */
 
-               bd->inbufBits = (bd->inbufBits<<8) | bd->inbuf[bd->inbufPos++];
+               bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
                bd->inbufBitCount += 8;
        }
 
@@ -205,7 +210,7 @@ static int get_next_block(bunzip_data *bd)
                /* Get next value */
 
                for (j = 0; get_bits(bd, 1); j++)
-                       if (j>=groupCount) return RETVAL_DATA_ERROR;
+                       if (j >= groupCount) return RETVAL_DATA_ERROR;
 
                /* Decode MTF to get the next selector */
 
@@ -320,19 +325,20 @@ static int get_next_block(bunzip_data *bd)
                        t += temp[i];
                        base[i+1] = pp - t;
                }
-               limit[maxLen+1] = INT_MAX; /* Sentinal value for reading next sym. */
+               limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */
                limit[maxLen] = pp + temp[maxLen] - 1;
                base[minLen] = 0;
        }
 
        /* We've finished reading and digesting the block header.  Now read this
           block's Huffman coded symbols from the file and undo the Huffman coding
-          and run length encoding, saving the result into dbuf[dbufCount++]=uc */
+          and run length encoding, saving the result into dbuf[dbufCount++] = uc */
 
        /* Initialize symbol occurrence counters and symbol Move To Front table */
 
+       memset(byteCount, 0, sizeof(byteCount)); /* smaller, maybe slower? */
        for (i = 0; i < 256; i++) {
-               byteCount[i] = 0;
+               //byteCount[i] = 0;
                mtfSymbol[i] = (unsigned char)i;
        }
 
@@ -547,7 +553,7 @@ int read_bunzip(bunzip_data *bd, char *outbuf, int len)
                        /* If the output buffer is full, snapshot state and return */
 
                        if (gotcount >= len) {
-                               bd->writePos  =pos;
+                               bd->writePos = pos;
                                bd->writeCurrent = current;
                                bd->writeCopies++;
                                return len;
@@ -573,8 +579,8 @@ int read_bunzip(bunzip_data *bd, char *outbuf, int len)
                        current = pos & 0xff;
                        pos >>= 8;
 
-                       /* After 3 consecutive copies of the same byte, the 4th is a repeat
-                          count.  We count down from 4 instead
+                       /* After 3 consecutive copies of the same byte, the 4th
+                        * is a repeat count.  We count down from 4 instead
                         * of counting up because testing for non-zero is faster */
 
                        if (--bd->writeRunCountdown) {
@@ -606,7 +612,7 @@ int read_bunzip(bunzip_data *bd, char *outbuf, int len)
                /* If this block had a CRC error, force file level CRC error. */
 
                if (bd->writeCRC != bd->headerCRC) {
-                       bd->totalCRC = bd->headerCRC+1;
+                       bd->totalCRC = bd->headerCRC + 1;
                        return RETVAL_LAST_BLOCK;
                }
        }
@@ -713,8 +719,8 @@ unpack_bz2_stream(int src_fd, int dst_fd)
                for (;;) {
                        i = read_bunzip(bd, outbuf, IOBUF_SIZE);
                        if (i <= 0) break;
-                       if (i != safe_write(dst_fd, outbuf, i)) {
-                               i = RETVAL_UNEXPECTED_OUTPUT_EOF;
+                       if (i != full_write(dst_fd, outbuf, i)) {
+                               i = RETVAL_SHORT_WRITE;
                                break;
                        }
                        USE_DESKTOP(total_written += i;)
@@ -729,8 +735,8 @@ unpack_bz2_stream(int src_fd, int dst_fd)
                } else {
                        i = RETVAL_OK;
                }
-       } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
-               bb_error_msg("unexpected EOF");
+       } else if (i == RETVAL_SHORT_WRITE) {
+               bb_error_msg("short write");
        } else {
                bb_error_msg("bunzip error %d", i);
        }