aboutsummaryrefslogtreecommitdiff
path: root/src/liblzma/check/crc32_x86.s
diff options
context:
space:
mode:
Diffstat (limited to 'src/liblzma/check/crc32_x86.s')
-rw-r--r--src/liblzma/check/crc32_x86.s217
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