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gzip: optionally faster put_32bit()

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function                                             old     new   delta
put_32bit                                             22      55     +33

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-01-31 00:42:29 +01:00
parent b7dfbbcdaa
commit 631c16855a
1 changed files with 14 additions and 2 deletions
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16
archival/gzip.c
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@ -454,7 +454,7 @@ static void put_16bit(ush w)
if (outcnt < OUTBUFSIZ-2) { if (outcnt < OUTBUFSIZ-2) {
/* Common case */ /* Common case */
ush *dst16 = (void*) dst; ush *dst16 = (void*) dst;
*dst16 = w; /* unalinged LSB 16-bit store */ *dst16 = w; /* unaligned LSB 16-bit store */
G1.outcnt = outcnt + 2; G1.outcnt = outcnt + 2;
return; return;
} }
@ -480,6 +480,18 @@ static void put_16bit(ush w)
static void put_32bit(ulg n) static void put_32bit(ulg n)
{ {
#if CONFIG_GZIP_FAST > 0 \
&& BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
unsigned outcnt = G1.outcnt;
if (outcnt < OUTBUFSIZ-4) {
/* Common case */
uch *dst = &G1.outbuf[outcnt];
ulg *dst32 = (void*) dst;
*dst32 = n; /* unaligned LSB 32-bit store */
G1.outcnt = outcnt + 4;
return;
}
#endif
put_16bit(n); put_16bit(n);
put_16bit(n >> 16); put_16bit(n >> 16);
} }
@ -544,7 +556,7 @@ static void send_bits(unsigned value, unsigned length)
*/ */
value >>= (BUF_SIZE - G1.bi_valid); value >>= (BUF_SIZE - G1.bi_valid);
if (BUF_SIZE == 32) { if (BUF_SIZE == 32) {
put_32bit(new_buf); /* maybe unroll to 2*put_16bit()? */ put_32bit(new_buf);
} else { /* 16 */ } else { /* 16 */
put_16bit(new_buf); put_16bit(new_buf);
} }