git.iko.soy/text
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Optimize latin1-to-UTF16 C-implementation by using 32-bit loads
ea0e522Herbert Valerio Riedel
cbits/cbits.c+24
compare with master
unifiedsplit
@@ -71,6 +71,30 @@ _hs_text_decode_latin1(uint16_t *dest, const uint8_t const *src,
71 const uint8_t const *srcend)
71 const uint8_t const *srcend)
72{
72{
73 const uint8_t *p = src;
73 const uint8_t *p = src;
74+
75+#if defined(__i386__) || defined(__x86_64__)
76+ /* This optimization works on a little-endian systems by using
77+ (aligned) 32-bit loads instead of 8-bit loads
78+ */
79+
80+ /* consume unaligned prefix */
81+ while (p != srcend && (uintptr_t)p & 0x3)
82+ *dest++ = *p++;
83+
84+ /* iterate over 32-bit aligned loads */
85+ while (p < srcend - 3) {
86+ const uint32_t w = *((const uint32_t *)p);
87+
88+ *dest++ = w & 0xff;
89+ *dest++ = (w >> 8) & 0xff;
90+ *dest++ = (w >> 16) & 0xff;
91+ *dest++ = (w >> 24) & 0xff;
92+
93+ p += 4;
94+ }
95+#endif
96+
97+ /* handle unaligned suffix */
74 while (p != srcend)
98 while (p != srcend)
75 *dest++ = *p++;
99 *dest++ = *p++;
76}
100}