2 * Speed-optimized CRC64 using slicing-by-four algorithm
4 * This uses only i386 instructions, but it is optimized for i686 and later
5 * (including e.g. Pentium II/III/IV, Athlon XP, and Core 2).
7 * Authors: Igor Pavlov (original CRC32 assembly code)
8 * Lasse Collin (CRC64 adaptation of the modified CRC32 code)
10 * This file has been put into the public domain.
11 * You can do whatever you want with this file.
13 * This code needs lzma_crc64_table, which can be created using the
16 uint64_t lzma_crc64_table[4][256];
22 static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
24 for (size_t s = 0; s < 4; ++s) {
25 for (size_t b = 0; b < 256; ++b) {
26 uint64_t r = s == 0 ? b : lzma_crc64_table[s - 1][b];
28 for (size_t i = 0; i < 8; ++i) {
30 r = (r >> 1) ^ poly64;
35 lzma_crc64_table[s][b] = r;
40 * The prototype of the CRC64 function:
41 * extern uint64_t lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc);
45 * On some systems, the functions need to be prefixed. The prefix is
46 * usually an underscore.
48 #ifndef __USER_LABEL_PREFIX__
49 # define __USER_LABEL_PREFIX__
51 #define MAKE_SYM_CAT(prefix, sym) prefix ## sym
52 #define MAKE_SYM(prefix, sym) MAKE_SYM_CAT(prefix, sym)
53 #define LZMA_CRC64 MAKE_SYM(__USER_LABEL_PREFIX__, lzma_crc64)
54 #define LZMA_CRC64_TABLE MAKE_SYM(__USER_LABEL_PREFIX__, lzma_crc64_table)
57 * Solaris assembler doesn't have .p2align, and Darwin uses .align
58 * differently than GNU/Linux and Solaris.
60 #if defined(__MACH__) || defined(__MSDOS__)
61 # define ALIGN(pow2, abs) .align pow2
63 # define ALIGN(pow2, abs) .align abs
69 #if !defined(__MACH__) && !defined(_WIN32) && !defined(__MSDOS__)
70 .type LZMA_CRC64, @function
80 * %edi size or buf + size
81 * %ebx lzma_crc64_table
89 movl 0x14(%esp), %esi /* buf */
90 movl 0x18(%esp), %edi /* size */
91 movl 0x1C(%esp), %eax /* crc LSB */
92 movl 0x20(%esp), %edx /* crc MSB */
95 * Store the address of lzma_crc64_table to %ebx. This is needed to
96 * get position-independent code (PIC).
98 * The PIC macro is defined by libtool, while __PIC__ is defined
99 * by GCC but only on some systems. Testing for both makes it simpler
100 * to test this code without libtool, and keeps the code working also
101 * when built with libtool but using something else than GCC.
103 #if !defined(PIC) && !defined(__PIC__)
105 movl $LZMA_CRC64_TABLE, %ebx
106 #elif defined(__MACH__)
110 leal .L_lzma_crc64_table$non_lazy_ptr-.L_pic(%ebx), %ebx
115 addl $_GLOBAL_OFFSET_TABLE_, %ebx
116 movl LZMA_CRC64_TABLE@GOT(%ebx), %ebx
119 /* Complement the initial value. */
125 * Check if there is enough input to use slicing-by-four.
126 * We need eight bytes, because the loop pre-reads four bytes.
131 /* Check if we have reached alignment of four bytes. */
135 /* Calculate CRC of the next input byte. */
141 xorl (%ebx, %ebp, 8), %eax
143 xorl 4(%ebx, %ebp, 8), %edx
149 * If we get here, there's at least eight bytes of aligned input
150 * available. Make %edi multiple of four bytes. Store the possible
151 * remainder over the "size" variable in the argument stack.
153 movl %edi, 0x18(%esp)
155 subl %edi, 0x18(%esp)
158 * Let %edi be buf + size - 4 while running the main loop. This way
159 * we can compare for equality to determine when exit the loop.
164 /* Read in the first four aligned bytes. */
170 movl 0x1800(%ebx, %ebp, 8), %eax
172 movl 0x1804(%ebx, %ebp, 8), %edx
174 xorl 0x1000(%ebx, %ebp, 8), %eax
175 xorl 0x1004(%ebx, %ebp, 8), %edx
178 xorl 0x0800(%ebx, %ebp, 8), %eax
179 xorl 0x0804(%ebx, %ebp, 8), %edx
182 xorl (%ebx, %ebp, 8), %eax
183 xorl 4(%ebx, %ebp, 8), %edx
185 /* Check for end of aligned input. */
189 * Copy the next input byte to %ecx. It is slightly faster to
190 * read it here than at the top of the loop.
196 * Process the remaining four bytes, which we have already
201 movl 0x1800(%ebx, %ebp, 8), %eax
203 movl 0x1804(%ebx, %ebp, 8), %edx
205 xorl 0x1000(%ebx, %ebp, 8), %eax
206 xorl 0x1004(%ebx, %ebp, 8), %edx
209 xorl 0x0800(%ebx, %ebp, 8), %eax
210 xorl 0x0804(%ebx, %ebp, 8), %edx
213 xorl (%ebx, %ebp, 8), %eax
214 xorl 4(%ebx, %ebp, 8), %edx
216 /* Copy the number of remaining bytes to %edi. */
217 movl 0x18(%esp), %edi
220 /* Check for end of input. */
224 /* Calculate CRC of the next input byte. */
230 xorl (%ebx, %ebp, 8), %eax
232 xorl 4(%ebx, %ebp, 8), %edx
237 /* Complement the final value. */
247 #if defined(PIC) || defined(__PIC__)
254 #if defined(__MACH__) && (defined(PIC) || defined(__PIC__))
256 .section __IMPORT,__pointers,non_lazy_symbol_pointers
257 .L_lzma_crc64_table$non_lazy_ptr:
258 .indirect_symbol LZMA_CRC64_TABLE
261 #elif defined(_WIN32)
262 # ifndef LZMA_API_STATIC
263 /* This is equivalent of __declspec(dllexport). */
265 .ascii " -export:lzma_crc64"
268 #elif !defined(__MSDOS__)
270 .size LZMA_CRC64, .-LZMA_CRC64
274 * This is needed to support non-executable stack. It's ugly to
275 * use __linux__ here, but I don't know a way to detect when
276 * we are using GNU assembler.
278 #if defined(__ELF__) && defined(__linux__)
279 .section .note.GNU-stack,"",@progbits