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string.c (search_nonascii): faster search using integer match

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If you define `SIMPLE_SEARCH_NONASCII`, you can use old, naive
implementation of search_nonascii(). You may want to use the old one for
code size constraint for example.
This commit is contained in:
Yukihiro "Matz" Matsumoto
2024-01-22 07:46:31 +09:00
parent f41593f55a
commit 4108b85c62
1 changed files with 66 additions and 0 deletions
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src/string.c
+66
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@@ -267,6 +267,9 @@ mrb_gc_free_str(mrb_state *mrb, struct RString *str)
#define NOASCII(c) ((c) & 0x80)
#ifdef SIMPLE_SEARCH_NONASCII
/* the naive implementation. define SIMPLE_SEARCH_NONASCII, */
/* if you need it for any constraint (e.g. code size). */
static const char*
search_nonascii(const char* p, const char *e)
{
@@ -276,6 +279,69 @@ search_nonascii(const char* p, const char *e)
return e;
}
#else
#ifdef MRB_64BIT
# define NONASCII_MASK 0x8080808080808080ULL
#else /* MRB_32BIT */
# define NONASCII_MASK 0x80808080UL
#endif
static const char*
search_nonascii(const char *p, const char *e)
{
if (e - p >= sizeof(void*)) {
if ((uintptr_t)p % sizeof(void*)) {
int l = sizeof(void*) - (uintptr_t)p % sizeof(void*);
p += l;
switch (l) {
#ifdef MRB_64BIT
case 7: if (p[-7]&0x80) return p-7;
case 6: if (p[-6]&0x80) return p-6;
case 5: if (p[-5]&0x80) return p-5;
case 4: if (p[-4]&0x80) return p-4;
#endif
case 3: if (p[-3]&0x80) return p-3;
case 2: if (p[-2]&0x80) return p-2;
case 1: if (p[-1]&0x80) return p-1;
case 0: break;
}
}
const uintptr_t *s = (uintptr_t*)p;
const uintptr_t *t = (uintptr_t*)(e - (sizeof(void*)-1));
for (;s < t; s++) {
if (*s & NONASCII_MASK) {
p = (const char*)s;
if (NOASCII(p[0])) return p+0;
if (NOASCII(p[1])) return p+1;
if (NOASCII(p[2])) return p+2;
if (NOASCII(p[3])) return p+3;
if (NOASCII(p[4])) return p+4;
if (NOASCII(p[5])) return p+5;
if (NOASCII(p[6])) return p+6;
if (NOASCII(p[7])) return p+7;
}
}
}
switch (e - p) {
default:
#ifdef MRB_64BIT
case 7: if (e[-7]&0x80) return e-7;
case 6: if (e[-6]&0x80) return e-6;
case 5: if (e[-5]&0x80) return e-5;
case 4: if (e[-4]&0x80) return e-4;
#endif
case 3: if (e[-3]&0x80) return e-3;
case 2: if (e[-2]&0x80) return e-2;
case 1: if (e[-1]&0x80) return e-1;
}
return e;
}
#endif /* SIMPLE_SEARCH_NONASCII */
#define utf8_islead(c) ((unsigned char)((c)&0xc0) != 0x80)
extern const char mrb_utf8len_table[];