468731a86
Denys Vlasenko
2018-01-31
Subject
gzip: code shrink and speedup
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Architecture & Compiler Flags
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Build Log
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Commit Diff GitHub →
archival/gzip.c+17 -12
| @@ -478,15 +478,14 @@ static void put_16bit(ush 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) | |
| { | |
| - | #if CONFIG_GZIP_FAST > 0 \ |
| - | && BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN |
| + | #if OPTIMIZED_PUT_32BIT |
| unsigned outcnt = G1.outcnt; | |
| if (outcnt < OUTBUFSIZ-4) { | |
| /* Common case */ | |
| - | uch *dst = &G1.outbuf[outcnt]; |
| - | ulg *dst32 = (void*) dst; |
| + | ulg *dst32 = (void*) &G1.outbuf[outcnt]; |
| *dst32 = n; /* unaligned LSB 32-bit store */ | |
| G1.outcnt = outcnt + 4; | |
| return; | |
| @@ -1951,7 +1950,7 @@ static void bi_init(void) | |
| /* =========================================================================== | |
| * Initialize the "longest match" routines for a new file | |
| */ | |
| - | static void lm_init(ush * flagsp) |
| + | static void lm_init(unsigned *flags16p) |
| { | |
| unsigned j; | |
| @@ -1960,7 +1959,7 @@ static void lm_init(ush * flagsp) | |
| /* prev will be initialized on the fly */ | |
| /* 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 */ | |
| //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"); | |
| /* Construct the codes of the static literal tree */ | |
| - | /* already zeroed - it's in bss |
| - | for (n = 0; n <= MAX_BITS; n++) |
| - | G2.bl_count[n] = 0; */ |
| + | //for (n = 0; n <= MAX_BITS; n++) // globals are zeroed in pack_gzip() |
| + | // G2.bl_count[n] = 0; |
| n = 0; | |
| while (n <= 143) { | |
| @@ -2088,7 +2086,7 @@ static void ct_init(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() | |
| @@ -2104,10 +2102,17 @@ static void zip(void) | |
| bi_init(); | |
| ct_init(); | |
| + | deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */ |
| lm_init(&deflate_flags); | |
| - | put_8bit(deflate_flags); /* extra flags */ |
| - | put_8bit(3); /* OS identifier = 3 (Unix) */ |
| + | put_16bit(deflate_flags | 0x300); /* extra flags. OS id = 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(); | |