diff options
Diffstat (limited to 'src/liblzma/check/crc32_x86.s')
| -rw-r--r-- | src/liblzma/check/crc32_x86.s | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/src/liblzma/check/crc32_x86.s b/src/liblzma/check/crc32_x86.s new file mode 100644 index 00000000..ad4ef097 --- /dev/null +++ b/src/liblzma/check/crc32_x86.s @@ -0,0 +1,217 @@ +/* + * Speed-optimized CRC32 using slicing-by-eight algorithm + * Instruction set: i386 + * Optimized for: i686 + * + * This code has been put into the public domain by its authors: + * Original code by Igor Pavlov <http://7-zip.org/> + * Position-independent version by Lasse Collin <lasse.collin@tukaani.org> + * + * This code needs lzma_crc32_table, which can be created using the + * following C code: + +uint32_t lzma_crc32_table[8][256]; + +void +init_table(void) +{ + // IEEE-802.3 (CRC32) + static const uint32_t poly32 = UINT32_C(0xEDB88320); + + // Castagnoli (CRC32C) + // static const uint32_t poly32 = UINT32_C(0x82F63B78); + + // Koopman + // static const uint32_t poly32 = UINT32_C(0xEB31D82E); + + for (size_t s = 0; s < 8; ++s) { + for (size_t b = 0; b < 256; ++b) { + uint32_t r = s == 0 ? b : lzma_crc32_table[s - 1][b]; + + for (size_t i = 0; i < 8; ++i) { + if (r & 1) + r = (r >> 1) ^ poly32; + else + r >>= 1; + } + + lzma_crc32_table[s][b] = r; + } + } +} + + * The prototype of the CRC32 function: + * extern uint32_t lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc); + */ + + .text + .global lzma_crc32 + .type lzma_crc32, @function + + .align 16 +lzma_crc32: + /* + * Register usage: + * %eax crc + * %esi buf + * %edi size or buf + size + * %ebx lzma_crc32_table + * %ebp Table index + * %ecx Temporary + * %edx Temporary + */ + pushl %ebx + pushl %esi + pushl %edi + pushl %ebp + movl 0x14(%esp), %esi /* buf */ + movl 0x18(%esp), %edi /* size */ + movl 0x1C(%esp), %eax /* crc */ + + /* + * Store the address of lzma_crc32_table to %ebx. This is needed to + * get position-independent code (PIC). + */ + call .L_PIC +.L_PIC: + popl %ebx + addl $_GLOBAL_OFFSET_TABLE_+[.-.L_PIC], %ebx + movl lzma_crc32_table@GOT(%ebx), %ebx + + /* Complement the initial value. */ + notl %eax + + .align 16 +.L_align: + /* + * Check if there is enough input to use slicing-by-eight. + * We need 16 bytes, because the loop pre-reads eight bytes. + */ + cmpl $16, %edi + jl .L_rest + + /* Check if we have reached alignment of eight bytes. */ + testl $7, %esi + jz .L_slice + + /* Calculate CRC of the next input byte. */ + movzbl (%esi), %ebp + incl %esi + movzbl %al, %ecx + xorl %ecx, %ebp + shrl $8, %eax + xorl (%ebx, %ebp, 4), %eax + decl %edi + jmp .L_align + + .align 4 +.L_slice: + /* + * If we get here, there's at least 16 bytes of aligned input + * available. Make %edi multiple of eight bytes. Store the possible + * remainder over the "size" variable in the argument stack. + */ + movl %edi, 0x18(%esp) + andl $-8, %edi + subl %edi, 0x18(%esp) + + /* + * Let %edi be buf + size - 8 while running the main loop. This way + * we can compare for equality to determine when exit the loop. + */ + addl %esi, %edi + subl $8, %edi + + /* Read in the first eight aligned bytes. */ + xorl (%esi), %eax + movl 4(%esi), %ecx + movzbl %cl, %ebp + +.L_loop: + movl 0x0C00(%ebx, %ebp, 4), %edx + movzbl %ch, %ebp + xorl 0x0800(%ebx, %ebp, 4), %edx + shrl $16, %ecx + xorl 8(%esi), %edx + movzbl %cl, %ebp + xorl 0x0400(%ebx, %ebp, 4), %edx + movzbl %ch, %ebp + xorl (%ebx, %ebp, 4), %edx + movzbl %al, %ebp + + /* + * Read the next four bytes, for which the CRC is calculated + * on the next interation of the loop. + */ + movl 12(%esi), %ecx + + xorl 0x1C00(%ebx, %ebp, 4), %edx + movzbl %ah, %ebp + shrl $16, %eax + xorl 0x1800(%ebx, %ebp, 4), %edx + movzbl %ah, %ebp + movzbl %al, %eax + movl 0x1400(%ebx, %eax, 4), %eax + addl $8, %esi + xorl %edx, %eax + xorl 0x1000(%ebx, %ebp, 4), %eax + + /* Check for end of aligned input. */ + cmpl %edi, %esi + movzbl %cl, %ebp + jne .L_loop + + /* + * Process the remaining eight bytes, which we have already + * copied to %ecx and %edx. + */ + movl 0x0C00(%ebx, %ebp, 4), %edx + movzbl %ch, %ebp + xorl 0x0800(%ebx, %ebp, 4), %edx + shrl $16, %ecx + movzbl %cl, %ebp + xorl 0x0400(%ebx, %ebp, 4), %edx + movzbl %ch, %ebp + xorl (%ebx, %ebp, 4), %edx + movzbl %al, %ebp + + xorl 0x1C00(%ebx, %ebp, 4), %edx + movzbl %ah, %ebp + shrl $16, %eax + xorl 0x1800(%ebx, %ebp, 4), %edx + movzbl %ah, %ebp + movzbl %al, %eax + movl 0x1400(%ebx, %eax, 4), %eax + addl $8, %esi + xorl %edx, %eax + xorl 0x1000(%ebx, %ebp, 4), %eax + + /* Copy the number of remaining bytes to %edi. */ + movl 0x18(%esp), %edi + +.L_rest: + /* Check for end of input. */ + testl %edi, %edi + jz .L_return + + /* Calculate CRC of the next input byte. */ + movzbl (%esi), %ebp + incl %esi + movzbl %al, %ecx + xorl %ecx, %ebp + shrl $8, %eax + xorl (%ebx, %ebp, 4), %eax + decl %edi + jmp .L_rest + +.L_return: + /* Complement the final value. */ + notl %eax + + popl %ebp + popl %edi + popl %esi + popl %ebx + ret + + .size lzma_crc32, .-lzma_crc32 |