3d4f688a1
Denys Vlasenko
2018-04-08
Subject
lzop: buffer several 32-bit writes when we start a new compressed block
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Commit Diff GitHub →
archival/lzop.c+21 -11
| @@ -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); | |