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cabac.h
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1 /*
2  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVCODEC_X86_CABAC_H
22 #define AVCODEC_X86_CABAC_H
23 
24 #include "libavcodec/cabac.h"
25 #include "libavutil/attributes.h"
26 #include "libavutil/x86/asm.h"
27 #include "libavutil/internal.h"
28 #include "config.h"
29 
30 #if (defined(__i386) && defined(__clang__) && (__clang_major__<2 || (__clang_major__==2 && __clang_minor__<10)))\
31  || ( !defined(__clang__) && defined(__llvm__) && __GNUC__==4 && __GNUC_MINOR__==2 && __GNUC_PATCHLEVEL__<=1)
32 # define BROKEN_COMPILER 1
33 #else
34 # define BROKEN_COMPILER 0
35 #endif
36 
37 #if HAVE_INLINE_ASM
38 
39 #ifndef UNCHECKED_BITSTREAM_READER
40 #define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
41 #endif
42 
43 #if UNCHECKED_BITSTREAM_READER
44 #define END_CHECK(end) ""
45 #else
46 #define END_CHECK(end) \
47  "cmp "end" , %%"REG_c" \n\t"\
48  "jge 1f \n\t"
49 #endif
50 
51 #ifdef BROKEN_RELOCATIONS
52 #define TABLES_ARG , "r"(tables)
53 
54 #if HAVE_FAST_CMOV
55 #define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
56  "cmp "low" , "tmp" \n\t"\
57  "cmova %%ecx , "range" \n\t"\
58  "sbb %%rcx , %%rcx \n\t"\
59  "and %%ecx , "tmp" \n\t"\
60  "xor %%rcx , "retq" \n\t"\
61  "sub "tmp" , "low" \n\t"
62 #else /* HAVE_FAST_CMOV */
63 #define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
64 /* P4 Prescott has crappy cmov,sbb,64bit shift so avoid them */ \
65  "sub "low" , "tmp" \n\t"\
66  "sar $31 , "tmp" \n\t"\
67  "sub %%ecx , "range" \n\t"\
68  "and "tmp" , "range" \n\t"\
69  "add %%ecx , "range" \n\t"\
70  "shl $17 , %%ecx \n\t"\
71  "and "tmp" , %%ecx \n\t"\
72  "sub %%ecx , "low" \n\t"\
73  "xor "tmp" , "ret" \n\t"\
74  "movslq "ret" , "retq" \n\t"
75 #endif /* HAVE_FAST_CMOV */
76 
77 #define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, norm_off, lps_off, mlps_off, tables) \
78  "movzbl "statep" , "ret" \n\t"\
79  "mov "range" , "tmp" \n\t"\
80  "and $0xC0 , "range" \n\t"\
81  "lea ("ret", "range", 2), %%ecx \n\t"\
82  "movzbl "lps_off"("tables", %%rcx), "range" \n\t"\
83  "sub "range" , "tmp" \n\t"\
84  "mov "tmp" , %%ecx \n\t"\
85  "shl $17 , "tmp" \n\t"\
86  BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
87  "movzbl "norm_off"("tables", "rangeq"), %%ecx \n\t"\
88  "shl %%cl , "range" \n\t"\
89  "movzbl "mlps_off"+128("tables", "retq"), "tmp" \n\t"\
90  "shl %%cl , "low" \n\t"\
91  "mov "tmpbyte" , "statep" \n\t"\
92  "test "lowword" , "lowword" \n\t"\
93  "jnz 2f \n\t"\
94  "mov "byte" , %%"REG_c" \n\t"\
95  END_CHECK(end)\
96  "add"OPSIZE" $2 , "byte" \n\t"\
97  "1: \n\t"\
98  "movzwl (%%"REG_c") , "tmp" \n\t"\
99  "lea -1("low") , %%ecx \n\t"\
100  "xor "low" , %%ecx \n\t"\
101  "shr $15 , %%ecx \n\t"\
102  "bswap "tmp" \n\t"\
103  "shr $15 , "tmp" \n\t"\
104  "movzbl "norm_off"("tables", %%rcx), %%ecx \n\t"\
105  "sub $0xFFFF , "tmp" \n\t"\
106  "neg %%ecx \n\t"\
107  "add $7 , %%ecx \n\t"\
108  "shl %%cl , "tmp" \n\t"\
109  "add "tmp" , "low" \n\t"\
110  "2: \n\t"
111 
112 #else /* BROKEN_RELOCATIONS */
113 #define TABLES_ARG
114 #define RIP_ARG
115 
116 #if HAVE_FAST_CMOV
117 #define BRANCHLESS_GET_CABAC_UPDATE(ret, low, range, tmp)\
118  "mov "tmp" , %%ecx \n\t"\
119  "shl $17 , "tmp" \n\t"\
120  "cmp "low" , "tmp" \n\t"\
121  "cmova %%ecx , "range" \n\t"\
122  "sbb %%ecx , %%ecx \n\t"\
123  "and %%ecx , "tmp" \n\t"\
124  "xor %%ecx , "ret" \n\t"\
125  "sub "tmp" , "low" \n\t"
126 #else /* HAVE_FAST_CMOV */
127 #define BRANCHLESS_GET_CABAC_UPDATE(ret, low, range, tmp)\
128  "mov "tmp" , %%ecx \n\t"\
129  "shl $17 , "tmp" \n\t"\
130  "sub "low" , "tmp" \n\t"\
131  "sar $31 , "tmp" \n\t" /*lps_mask*/\
132  "sub %%ecx , "range" \n\t" /*RangeLPS - range*/\
133  "and "tmp" , "range" \n\t" /*(RangeLPS - range)&lps_mask*/\
134  "add %%ecx , "range" \n\t" /*new range*/\
135  "shl $17 , %%ecx \n\t"\
136  "and "tmp" , %%ecx \n\t"\
137  "sub %%ecx , "low" \n\t"\
138  "xor "tmp" , "ret" \n\t"
139 #endif /* HAVE_FAST_CMOV */
140 
141 #define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, norm_off, lps_off, mlps_off, tables) \
142  "movzbl "statep" , "ret" \n\t"\
143  "mov "range" , "tmp" \n\t"\
144  "and $0xC0 , "range" \n\t"\
145  "movzbl "MANGLE(ff_h264_cabac_tables)"+"lps_off"("ret", "range", 2), "range" \n\t"\
146  "sub "range" , "tmp" \n\t"\
147  BRANCHLESS_GET_CABAC_UPDATE(ret, low, range, tmp) \
148  "movzbl "MANGLE(ff_h264_cabac_tables)"+"norm_off"("range"), %%ecx \n\t"\
149  "shl %%cl , "range" \n\t"\
150  "movzbl "MANGLE(ff_h264_cabac_tables)"+"mlps_off"+128("ret"), "tmp" \n\t"\
151  "shl %%cl , "low" \n\t"\
152  "mov "tmpbyte" , "statep" \n\t"\
153  "test "lowword" , "lowword" \n\t"\
154  " jnz 2f \n\t"\
155  "mov "byte" , %%"REG_c" \n\t"\
156  END_CHECK(end)\
157  "add"OPSIZE" $2 , "byte" \n\t"\
158  "1: \n\t"\
159  "movzwl (%%"REG_c") , "tmp" \n\t"\
160  "lea -1("low") , %%ecx \n\t"\
161  "xor "low" , %%ecx \n\t"\
162  "shr $15 , %%ecx \n\t"\
163  "bswap "tmp" \n\t"\
164  "shr $15 , "tmp" \n\t"\
165  "movzbl "MANGLE(ff_h264_cabac_tables)"+"norm_off"(%%ecx), %%ecx \n\t"\
166  "sub $0xFFFF , "tmp" \n\t"\
167  "neg %%ecx \n\t"\
168  "add $7 , %%ecx \n\t"\
169  "shl %%cl , "tmp" \n\t"\
170  "add "tmp" , "low" \n\t"\
171  "2: \n\t"
172 
173 #endif /* BROKEN_RELOCATIONS */
174 
175 #if HAVE_7REGS && !BROKEN_COMPILER
176 #define get_cabac_inline get_cabac_inline_x86
177 static av_always_inline int get_cabac_inline_x86(CABACContext *c,
178  uint8_t *const state)
179 {
180  int bit, tmp;
181 #ifdef BROKEN_RELOCATIONS
182  void *tables;
183 
184  __asm__ volatile(
185  "lea "MANGLE(ff_h264_cabac_tables)", %0 \n\t"
186  : "=&r"(tables)
187  );
188 #endif
189 
190  __asm__ volatile(
191  BRANCHLESS_GET_CABAC("%0", "%q0", "(%4)", "%1", "%w1",
192  "%2", "%q2", "%3", "%b3",
193  "%c6(%5)", "%c7(%5)",
194  AV_STRINGIFY(H264_NORM_SHIFT_OFFSET),
195  AV_STRINGIFY(H264_LPS_RANGE_OFFSET),
196  AV_STRINGIFY(H264_MLPS_STATE_OFFSET),
197  "%8")
198  : "=&r"(bit), "=&r"(c->low), "=&r"(c->range), "=&q"(tmp)
199  : "r"(state), "r"(c),
200  "i"(offsetof(CABACContext, bytestream)),
201  "i"(offsetof(CABACContext, bytestream_end))
202  TABLES_ARG
203  ,"1"(c->low), "2"(c->range)
204  : "%"REG_c, "memory"
205  );
206  return bit & 1;
207 }
208 #endif /* HAVE_7REGS */
209 
210 #if !BROKEN_COMPILER
211 #define get_cabac_bypass_sign get_cabac_bypass_sign_x86
212 static av_always_inline int get_cabac_bypass_sign_x86(CABACContext *c, int val)
213 {
214  x86_reg tmp;
215  __asm__ volatile(
216  "movl %c6(%2), %k1 \n\t"
217  "movl %c3(%2), %%eax \n\t"
218  "shl $17, %k1 \n\t"
219  "add %%eax, %%eax \n\t"
220  "sub %k1, %%eax \n\t"
221  "cltd \n\t"
222  "and %%edx, %k1 \n\t"
223  "add %k1, %%eax \n\t"
224  "xor %%edx, %%ecx \n\t"
225  "sub %%edx, %%ecx \n\t"
226  "test %%ax, %%ax \n\t"
227  "jnz 1f \n\t"
228  "mov %c4(%2), %1 \n\t"
229  "subl $0xFFFF, %%eax \n\t"
230  "movzwl (%1), %%edx \n\t"
231  "bswap %%edx \n\t"
232  "shrl $15, %%edx \n\t"
233 #if UNCHECKED_BITSTREAM_READER
234  "add $2, %1 \n\t"
235  "addl %%edx, %%eax \n\t"
236  "mov %1, %c4(%2) \n\t"
237 #else
238  "addl %%edx, %%eax \n\t"
239  "cmp %c5(%2), %1 \n\t"
240  "jge 1f \n\t"
241  "add"OPSIZE" $2, %c4(%2) \n\t"
242 #endif
243  "1: \n\t"
244  "movl %%eax, %c3(%2) \n\t"
245 
246  : "+c"(val), "=&r"(tmp)
247  : "r"(c),
248  "i"(offsetof(CABACContext, low)),
249  "i"(offsetof(CABACContext, bytestream)),
250  "i"(offsetof(CABACContext, bytestream_end)),
251  "i"(offsetof(CABACContext, range))
252  : "%eax", "%edx", "memory"
253  );
254  return val;
255 }
256 
257 #define get_cabac_bypass get_cabac_bypass_x86
258 static av_always_inline int get_cabac_bypass_x86(CABACContext *c)
259 {
260  x86_reg tmp;
261  int res;
262  __asm__ volatile(
263  "movl %c6(%2), %k1 \n\t"
264  "movl %c3(%2), %%eax \n\t"
265  "shl $17, %k1 \n\t"
266  "add %%eax, %%eax \n\t"
267  "sub %k1, %%eax \n\t"
268  "cltd \n\t"
269  "and %%edx, %k1 \n\t"
270  "add %k1, %%eax \n\t"
271  "inc %%edx \n\t"
272  "test %%ax, %%ax \n\t"
273  "jnz 1f \n\t"
274  "mov %c4(%2), %1 \n\t"
275  "subl $0xFFFF, %%eax \n\t"
276  "movzwl (%1), %%ecx \n\t"
277  "bswap %%ecx \n\t"
278  "shrl $15, %%ecx \n\t"
279  "addl %%ecx, %%eax \n\t"
280  "cmp %c5(%2), %1 \n\t"
281  "jge 1f \n\t"
282  "add"OPSIZE" $2, %c4(%2) \n\t"
283  "1: \n\t"
284  "movl %%eax, %c3(%2) \n\t"
285 
286  : "=&d"(res), "=&r"(tmp)
287  : "r"(c),
288  "i"(offsetof(CABACContext, low)),
289  "i"(offsetof(CABACContext, bytestream)),
290  "i"(offsetof(CABACContext, bytestream_end)),
291  "i"(offsetof(CABACContext, range))
292  : "%eax", "%ecx", "memory"
293  );
294  return res;
295 }
296 #endif /* !BROKEN_COMPILER */
297 
298 #endif /* HAVE_INLINE_ASM */
299 #endif /* AVCODEC_X86_CABAC_H */
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