Further pack optimisations by Ton Hospel

p4raw-id: //depot/perl@24012

diff --git a/pp_pack.c b/pp_pack.c
index 6c9b92a..204b17c 100644 (file)
--- a/pp_pack.c
+++ b/pp_pack.c
@@ -39,6 +39,8 @@
 #ifndef CHAR_BIT
 # define CHAR_BIT      8
 #endif
+/* Maximum number of bytes to which a byte can grow due to upgrade */
+#define UTF8_EXPAND    2
 
 /*
  * Offset for integer pack/unpack.
@@ -648,7 +650,7 @@ STMT_START {                                                \
 #define GROWING(utf8, cat, start, cur, in_len) \
 STMT_START {                                   \
     STRLEN glen = (in_len);                    \
-    if (utf8) glen *= 2;                       \
+    if (utf8) glen *= UTF8_EXPAND;             \
     if ((cur) + glen >= (start) + SvLEN(cat)) {        \
        (start) = sv_exp_grow(aTHX_ cat, glen); \
        (cur) = (start) + SvCUR(cat);           \
@@ -659,7 +661,7 @@ STMT_START {                                        \
 STMT_START {                                   \
     STRLEN glen = (in_len);                    \
     STRLEN gl = glen;                          \
-    if (utf8) gl *= 2;                         \
+    if (utf8) gl *= UTF8_EXPAND;               \
     if ((cur) + gl >= (start) + SvLEN(cat)) {  \
         *cur = '\0';                           \
         SvCUR(cat) = (cur) - (start);          \
@@ -2335,8 +2337,7 @@ marked_upgrade(pTHX_ SV *sv, tempsym_t *sym_ptr) {
        return;
     }
 
-    /* We assume a char translates to at most 2 UTF-8 bytes */
-    len = (from_end-from_ptr)*2+(from_ptr-from_start)+1;
+    len = (from_end-from_ptr)*UTF8_EXPAND+(from_ptr-from_start)+1;
     New('U', to_start, len, char);
     Copy(from_start, to_start, from_ptr-from_start, char);
     to_ptr = to_start + (from_ptr-from_start);
@@ -2643,9 +2644,10 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                    fromlen = len;
                    if (datumtype == 'Z' && fromlen > 0) fromlen--;
                }
-               /* assumes a byte expands to at most 2 bytes on upgrade:
-                  expected_length <= from_len*2 + (len-from_len) */
-               GROWING(0, cat, start, cur, fromlen+len);
+               /* assumes a byte expands to at most UTF8_EXPAND bytes on 
+                  upgrade, so:
+                  expected_length <= from_len*UTF8_EXPAND + (len-from_len) */
+               GROWING(0, cat, start, cur, fromlen*(UTF8_EXPAND-1)+len);
                len -= fromlen;
                while (fromlen > 0) {
                    cur = uvchr_to_utf8(cur, * (U8 *) aptr);
@@ -2921,11 +2923,12 @@ S_pack_rec(pTHX_ SV *cat, tempsym_t* symptr, SV **beglist, SV **endlist )
                      endb = uvuni_to_utf8_flags(buffer, auv,
                                                     ckWARN(WARN_UTF8) ?
                                                0 : UNICODE_ALLOW_ANY);
-                     if (cur >= end-(endb-buffer)*2) {
+                     if (cur+(endb-buffer)*UTF8_EXPAND >= end) {
                          *cur = '\0';
                          SvCUR(cat) = cur - start;
-                         GROWING(0, cat, start, cur, len+(endb-buffer)*2);
-                         end = start+SvLEN(cat)-UTF8_MAXLEN;
+                         GROWING(0, cat, start, cur, 
+                                 len+(endb-buffer)*UTF8_EXPAND);
+                         end = start+SvLEN(cat);
                      }
                      bytes_to_uni(aTHX_ buffer, endb-buffer, &cur);
                  } else {