1/*
2 * Speed-optimized CRC64 using slicing-by-four algorithm
3 *
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).
6 *
7 * Authors: Igor Pavlov (original CRC32 assembly code)
8 *          Lasse Collin (CRC64 adaptation of the modified CRC32 code)
9 *
10 * This file has been put into the public domain.
11 * You can do whatever you want with this file.
12 *
13 * This code needs lzma_crc64_table, which can be created using the
14 * following C code:
15
16uint64_t lzma_crc64_table[4][256];
17
18void
19init_table(void)
20{
21          // ECMA-182
22          static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
23
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];
27
28                              for (size_t i = 0; i < 8; ++i) {
29                                        if (r & 1)
30                                                  r = (r >> 1) ^ poly64;
31                                        else
32                                                  r >>= 1;
33                              }
34
35                              lzma_crc64_table[s][b] = r;
36                    }
37          }
38}
39
40 * The prototype of the CRC64 function:
41 * extern uint64_t lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc);
42 */
43
44/*
45 * On some systems, the functions need to be prefixed. The prefix is
46 * usually an underscore.
47 */
48#ifndef __USER_LABEL_PREFIX__
49#         define __USER_LABEL_PREFIX__
50#endif
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)
55
56/*
57 * Solaris assembler doesn't have .p2align, and Darwin uses .align
58 * differently than GNU/Linux and Solaris.
59 */
60#if defined(__APPLE__) || defined(__MSDOS__)
61#         define ALIGN(pow2, abs) .align pow2
62#else
63#         define ALIGN(pow2, abs) .align abs
64#endif
65
66          .text
67          .globl    LZMA_CRC64
68
69#if !defined(__APPLE__) && !defined(_WIN32) && !defined(__CYGWIN__) \
70                    && !defined(__MSDOS__)
71          .type     LZMA_CRC64, @function
72#endif
73
74          ALIGN(4, 16)
75LZMA_CRC64:
76          /*
77           * Register usage:
78           * %eax crc LSB
79           * %edx crc MSB
80           * %esi buf
81           * %edi size or buf + size
82           * %ebx lzma_crc64_table
83           * %ebp Table index
84           * %ecx Temporary
85           */
86          pushl     %ebx
87          pushl     %esi
88          pushl     %edi
89          pushl     %ebp
90          movl      0x14(%esp), %esi /* buf */
91          movl      0x18(%esp), %edi /* size */
92          movl      0x1C(%esp), %eax /* crc LSB */
93          movl      0x20(%esp), %edx /* crc MSB */
94
95          /*
96           * Store the address of lzma_crc64_table to %ebx. This is needed to
97           * get position-independent code (PIC).
98           *
99           * The PIC macro is defined by libtool, while __PIC__ is defined
100           * by GCC but only on some systems. Testing for both makes it simpler
101           * to test this code without libtool, and keeps the code working also
102           * when built with libtool but using something else than GCC.
103           *
104           * I understood that libtool may define PIC on Windows even though
105           * the code in Windows DLLs is not PIC in sense that it is in ELF
106           * binaries, so we need a separate check to always use the non-PIC
107           * code on Windows.
108           */
109#if (!defined(PIC) && !defined(__PIC__)) \
110                    || (defined(_WIN32) || defined(__CYGWIN__))
111          /* Not PIC */
112          movl      $ LZMA_CRC64_TABLE, %ebx
113#elif defined(__APPLE__)
114          /* Mach-O */
115          call      .L_get_pc
116.L_pic:
117          leal      .L_lzma_crc64_table$non_lazy_ptr-.L_pic(%ebx), %ebx
118          movl      (%ebx), %ebx
119#else
120          /* ELF */
121          call      .L_get_pc
122          addl      $_GLOBAL_OFFSET_TABLE_, %ebx
123          movl      LZMA_CRC64_TABLE@GOT(%ebx), %ebx
124#endif
125
126          /* Complement the initial value. */
127          notl      %eax
128          notl      %edx
129
130.L_align:
131          /*
132           * Check if there is enough input to use slicing-by-four.
133           * We need eight bytes, because the loop pre-reads four bytes.
134           */
135          cmpl      $8, %edi
136          jb        .L_rest
137
138          /* Check if we have reached alignment of four bytes. */
139          testl     $3, %esi
140          jz        .L_slice
141
142          /* Calculate CRC of the next input byte. */
143          movzbl    (%esi), %ebp
144          incl      %esi
145          movzbl    %al, %ecx
146          xorl      %ecx, %ebp
147          shrdl     $8, %edx, %eax
148          xorl      (%ebx, %ebp, 8), %eax
149          shrl      $8, %edx
150          xorl      4(%ebx, %ebp, 8), %edx
151          decl      %edi
152          jmp       .L_align
153
154.L_slice:
155          /*
156           * If we get here, there's at least eight bytes of aligned input
157           * available. Make %edi multiple of four bytes. Store the possible
158           * remainder over the "size" variable in the argument stack.
159           */
160          movl      %edi, 0x18(%esp)
161          andl      $-4, %edi
162          subl      %edi, 0x18(%esp)
163
164          /*
165           * Let %edi be buf + size - 4 while running the main loop. This way
166           * we can compare for equality to determine when exit the loop.
167           */
168          addl      %esi, %edi
169          subl      $4, %edi
170
171          /* Read in the first four aligned bytes. */
172          movl      (%esi), %ecx
173
174.L_loop:
175          xorl      %eax, %ecx
176          movzbl    %cl, %ebp
177          movl      0x1800(%ebx, %ebp, 8), %eax
178          xorl      %edx, %eax
179          movl      0x1804(%ebx, %ebp, 8), %edx
180          movzbl    %ch, %ebp
181          xorl      0x1000(%ebx, %ebp, 8), %eax
182          xorl      0x1004(%ebx, %ebp, 8), %edx
183          shrl      $16, %ecx
184          movzbl    %cl, %ebp
185          xorl      0x0800(%ebx, %ebp, 8), %eax
186          xorl      0x0804(%ebx, %ebp, 8), %edx
187          movzbl    %ch, %ebp
188          addl      $4, %esi
189          xorl      (%ebx, %ebp, 8), %eax
190          xorl      4(%ebx, %ebp, 8), %edx
191
192          /* Check for end of aligned input. */
193          cmpl      %edi, %esi
194
195          /*
196           * Copy the next input byte to %ecx. It is slightly faster to
197           * read it here than at the top of the loop.
198           */
199          movl      (%esi), %ecx
200          jb        .L_loop
201
202          /*
203           * Process the remaining four bytes, which we have already
204           * copied to %ecx.
205           */
206          xorl      %eax, %ecx
207          movzbl    %cl, %ebp
208          movl      0x1800(%ebx, %ebp, 8), %eax
209          xorl      %edx, %eax
210          movl      0x1804(%ebx, %ebp, 8), %edx
211          movzbl    %ch, %ebp
212          xorl      0x1000(%ebx, %ebp, 8), %eax
213          xorl      0x1004(%ebx, %ebp, 8), %edx
214          shrl      $16, %ecx
215          movzbl    %cl, %ebp
216          xorl      0x0800(%ebx, %ebp, 8), %eax
217          xorl      0x0804(%ebx, %ebp, 8), %edx
218          movzbl    %ch, %ebp
219          addl      $4, %esi
220          xorl      (%ebx, %ebp, 8), %eax
221          xorl      4(%ebx, %ebp, 8), %edx
222
223          /* Copy the number of remaining bytes to %edi. */
224          movl      0x18(%esp), %edi
225
226.L_rest:
227          /* Check for end of input. */
228          testl     %edi, %edi
229          jz        .L_return
230
231          /* Calculate CRC of the next input byte. */
232          movzbl    (%esi), %ebp
233          incl      %esi
234          movzbl    %al, %ecx
235          xorl      %ecx, %ebp
236          shrdl     $8, %edx, %eax
237          xorl      (%ebx, %ebp, 8), %eax
238          shrl      $8, %edx
239          xorl      4(%ebx, %ebp, 8), %edx
240          decl      %edi
241          jmp       .L_rest
242
243.L_return:
244          /* Complement the final value. */
245          notl      %eax
246          notl      %edx
247
248          popl      %ebp
249          popl      %edi
250          popl      %esi
251          popl      %ebx
252          ret
253
254#if defined(PIC) || defined(__PIC__)
255          ALIGN(4, 16)
256.L_get_pc:
257          movl      (%esp), %ebx
258          ret
259#endif
260
261#if defined(__APPLE__) && (defined(PIC) || defined(__PIC__))
262          /* Mach-O PIC */
263          .section __IMPORT,__pointers,non_lazy_symbol_pointers
264.L_lzma_crc64_table$non_lazy_ptr:
265          .indirect_symbol LZMA_CRC64_TABLE
266          .long 0
267
268#elif defined(_WIN32) || defined(__CYGWIN__)
269#         ifdef DLL_EXPORT
270          /* This is equivalent of __declspec(dllexport). */
271          .section .drectve
272          .ascii " -export:lzma_crc64"
273#         endif
274
275#elif !defined(__MSDOS__)
276          /* ELF */
277          .size     LZMA_CRC64, .-LZMA_CRC64
278#endif
279
280/*
281 * This is needed to support non-executable stack. It's ugly to
282 * use __linux__ here, but I don't know a way to detect when
283 * we are using GNU assembler.
284 */
285#if defined(__ELF__) && defined(__linux__)
286          .section  .note.GNU-stack,"",@progbits
287#endif
288