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gzip: code shrink and speedup

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function                                             old     new   delta
pack_gzip                                            908     861     -47

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-01-31 15:32:32 +01:00
parent 631c16855a
commit 468731a86b
1 changed files with 17 additions and 12 deletions
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29
archival/gzip.c
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@ -478,15 +478,14 @@ static void put_16bit(ush w)
put_8bit(w); put_8bit(w);
} }
#define OPTIMIZED_PUT_32BIT (CONFIG_GZIP_FAST > 0 && BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN)
static void put_32bit(ulg n) static void put_32bit(ulg n)
{ {
#if CONFIG_GZIP_FAST > 0 \ #if OPTIMIZED_PUT_32BIT
&& BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
unsigned outcnt = G1.outcnt; unsigned outcnt = G1.outcnt;
if (outcnt < OUTBUFSIZ-4) { if (outcnt < OUTBUFSIZ-4) {
/* Common case */ /* Common case */
uch *dst = &G1.outbuf[outcnt]; ulg *dst32 = (void*) &G1.outbuf[outcnt];
ulg *dst32 = (void*) dst;
*dst32 = n; /* unaligned LSB 32-bit store */ *dst32 = n; /* unaligned LSB 32-bit store */
G1.outcnt = outcnt + 4; G1.outcnt = outcnt + 4;
return; return;
@ -1951,7 +1950,7 @@ static void bi_init(void)
/* =========================================================================== /* ===========================================================================
* Initialize the "longest match" routines for a new file * Initialize the "longest match" routines for a new file
*/ */
static void lm_init(ush * flagsp) static void lm_init(unsigned *flags16p)
{ {
unsigned j; unsigned j;
@ -1960,7 +1959,7 @@ static void lm_init(ush * flagsp)
/* prev will be initialized on the fly */ /* prev will be initialized on the fly */
/* speed options for the general purpose bit flag */ /* speed options for the general purpose bit flag */
*flagsp |= 2; /* FAST 4, SLOW 2 */ *flags16p |= 2; /* FAST 4, SLOW 2 */
/* ??? reduce max_chain_length for binary files */ /* ??? reduce max_chain_length for binary files */
//G1.strstart = 0; // globals are zeroed in pack_gzip() //G1.strstart = 0; // globals are zeroed in pack_gzip()
@ -2044,9 +2043,8 @@ static void ct_init(void)
Assert(dist == 256, "ct_init: 256+dist != 512"); Assert(dist == 256, "ct_init: 256+dist != 512");
/* Construct the codes of the static literal tree */ /* Construct the codes of the static literal tree */
/* already zeroed - it's in bss //for (n = 0; n <= MAX_BITS; n++) // globals are zeroed in pack_gzip()
for (n = 0; n <= MAX_BITS; n++) // G2.bl_count[n] = 0;
G2.bl_count[n] = 0; */
n = 0; n = 0;
while (n <= 143) { while (n <= 143) {
@ -2088,7 +2086,7 @@ static void ct_init(void)
*/ */
static void zip(void) static void zip(void)
{ {
ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */ unsigned deflate_flags;
//G1.outcnt = 0; // globals are zeroed in pack_gzip() //G1.outcnt = 0; // globals are zeroed in pack_gzip()
@ -2104,10 +2102,17 @@ static void zip(void)
bi_init(); bi_init();
ct_init(); ct_init();
deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
lm_init(&deflate_flags); lm_init(&deflate_flags);
put_8bit(deflate_flags); /* extra flags */ put_16bit(deflate_flags | 0x300); /* extra flags. OS id = 3 (Unix) */
put_8bit(3); /* OS identifier = 3 (Unix) */
#if OPTIMIZED_PUT_32BIT
/* put_32bit() performs 32bit stores. If we use it in send_bits()... */
if (BUF_SIZE > 16)
/* then all stores are misaligned, unless we flush the buffer now */
flush_outbuf();
#endif
deflate(); deflate();