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lzop: buffer several 32-bit writes when we start a new compressed block

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function                                             old     new   delta
lzo_compress                                         483     531     +48

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-04-08 16:31:02 +02:00
parent 24ef5c6375
commit 3d4f688a19
1 changed files with 21 additions and 11 deletions
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32
archival/lzop.c
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@ -637,10 +637,8 @@ static NOINLINE int lzo_compress(const header_t *h)
int r = 0; /* LZO_E_OK */
uint8_t *const b1 = xzalloc(block_size);
uint8_t *const b2 = xzalloc(MAX_COMPRESSED_SIZE(block_size));
unsigned src_len = 0, dst_len = 0;
uint32_t d_adler32 = ADLER32_INIT_VALUE;
uint32_t d_crc32 = CRC32_INIT_VALUE;
int l;
uint8_t *wrk_mem = NULL;
if (h->method == M_LZO1X_1)
@ -651,16 +649,22 @@ static NOINLINE int lzo_compress(const header_t *h)
wrk_mem = xzalloc(LZO1X_999_MEM_COMPRESS);
for (;;) {
unsigned src_len, dst_len;
int l;
uint32_t wordbuf[6];
uint32_t *wordptr = wordbuf;
/* read a block */
l = full_read(0, b1, block_size);
src_len = (l > 0 ? l : 0);
/* write uncompressed block size */
write32(src_len);
/* exit if last block */
if (src_len == 0)
if (src_len == 0) {
write32(0);
break;
}
*wordptr++ = htonl(src_len);
/* compute checksum of uncompressed block */
if (h->flags32 & F_ADLER32_D)
@ -693,30 +697,36 @@ static NOINLINE int lzo_compress(const header_t *h)
if (r != 0 /*LZO_E_OK*/ || new_len != src_len)
bb_error_msg_and_die("%s: %s", "internal error", "optimization");
}
write32(dst_len);
*wordptr++ = htonl(dst_len);
} else {
/* data actually expanded => store data uncompressed */
write32(src_len);
*wordptr++ = htonl(src_len);
}
/* write checksum of uncompressed block */
if (h->flags32 & F_ADLER32_D)
write32(d_adler32);
*wordptr++ = htonl(d_adler32);
if (h->flags32 & F_CRC32_D)
write32(d_crc32);
*wordptr++ = htonl(d_crc32);
if (dst_len < src_len) {
/* write checksum of compressed block */
if (h->flags32 & F_ADLER32_C)
write32(lzo_adler32(ADLER32_INIT_VALUE, b2, dst_len));
*wordptr++ = htonl(lzo_adler32(ADLER32_INIT_VALUE, b2, dst_len));
if (h->flags32 & F_CRC32_C)
write32(lzo_crc32(CRC32_INIT_VALUE, b2, dst_len));
*wordptr++ = htonl(lzo_crc32(CRC32_INIT_VALUE, b2, dst_len));
}
xwrite(1, wordbuf, ((char*)wordptr) - ((char*)wordbuf));
if (dst_len < src_len) {
/* write compressed block data */
xwrite(1, b2, dst_len);
} else {
/* write uncompressed block data */
xwrite(1, b1, src_len);
}
// /* if full_read() was nevertheless "short", it was EOF */
// if (src_len < block_size)
// break;
}
free(wrk_mem);