FFmpeg
mathops.h
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1 /*
2  * simple math operations
3  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> et al
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #ifndef AVCODEC_X86_MATHOPS_H
23 #define AVCODEC_X86_MATHOPS_H
24 
25 #include "config.h"
26 
27 #include "libavutil/common.h"
28 #include "libavutil/x86/asm.h"
29 
30 #if HAVE_INLINE_ASM
31 
32 #if ARCH_X86_32
33 
34 #define MULL MULL
35 static av_always_inline av_const int MULL(int a, int b, unsigned shift)
36 {
37  int rt, dummy;
38  __asm__ (
39  "imull %3 \n\t"
40  "shrdl %4, %%edx, %%eax \n\t"
41  :"=a"(rt), "=d"(dummy)
42  :"a"(a), "rm"(b), "ci"((uint8_t)shift)
43  );
44  return rt;
45 }
46 
47 #define MULH MULH
48 static av_always_inline av_const int MULH(int a, int b)
49 {
50  int rt, dummy;
51  __asm__ (
52  "imull %3"
53  :"=d"(rt), "=a"(dummy)
54  :"a"(a), "rm"(b)
55  );
56  return rt;
57 }
58 
59 #define MUL64 MUL64
60 static av_always_inline av_const int64_t MUL64(int a, int b)
61 {
62  int64_t rt;
63  __asm__ (
64  "imull %2"
65  :"=A"(rt)
66  :"a"(a), "rm"(b)
67  );
68  return rt;
69 }
70 
71 #endif /* ARCH_X86_32 */
72 
73 #if HAVE_I686
74 /* median of 3 */
75 #define mid_pred mid_pred
76 static inline av_const int mid_pred(int a, int b, int c)
77 {
78  int i=b;
79  __asm__ (
80  "cmp %2, %1 \n\t"
81  "cmovg %1, %0 \n\t"
82  "cmovg %2, %1 \n\t"
83  "cmp %3, %1 \n\t"
84  "cmovl %3, %1 \n\t"
85  "cmp %1, %0 \n\t"
86  "cmovg %1, %0 \n\t"
87  :"+&r"(i), "+&r"(a)
88  :"r"(b), "r"(c)
89  );
90  return i;
91 }
92 
93 #if HAVE_6REGS
94 #define COPY3_IF_LT(x, y, a, b, c, d)\
95 __asm__ volatile(\
96  "cmpl %0, %3 \n\t"\
97  "cmovl %3, %0 \n\t"\
98  "cmovl %4, %1 \n\t"\
99  "cmovl %5, %2 \n\t"\
100  : "+&r" (x), "+&r" (a), "+r" (c)\
101  : "r" (y), "r" (b), "r" (d)\
102 );
103 #endif /* HAVE_6REGS */
104 
105 #endif /* HAVE_I686 */
106 
107 #define MASK_ABS(mask, level) \
108  __asm__ ("cdq \n\t" \
109  "xorl %1, %0 \n\t" \
110  "subl %1, %0 \n\t" \
111  : "+a"(level), "=&d"(mask))
112 
113 // avoid +32 for shift optimization (gcc should do that ...)
114 #define NEG_SSR32 NEG_SSR32
115 static inline int32_t NEG_SSR32( int32_t a, int8_t s){
116  __asm__ ("sarl %1, %0\n\t"
117  : "+r" (a)
118  : "ic" ((uint8_t)(-s))
119  );
120  return a;
121 }
122 
123 #define NEG_USR32 NEG_USR32
124 static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
125  __asm__ ("shrl %1, %0\n\t"
126  : "+r" (a)
127  : "ic" ((uint8_t)(-s))
128  );
129  return a;
130 }
131 
132 #endif /* HAVE_INLINE_ASM */
133 #endif /* AVCODEC_X86_MATHOPS_H */
av_const
#define av_const
Definition: attributes.h:84
b
#define b
Definition: input.c:41
MULH
#define MULH
Definition: mathops.h:42
s
#define s(width, name)
Definition: cbs_vp9.c:257
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
asm.h
NEG_SSR32
#define NEG_SSR32(a, s)
Definition: mathops.h:162
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
NEG_USR32
#define NEG_USR32(a, s)
Definition: mathops.h:166
i
int i
Definition: input.c:407
common.h
av_always_inline
#define av_always_inline
Definition: attributes.h:49
mid_pred
#define mid_pred
Definition: mathops.h:97
__asm__
__asm__(".macro parse_r var r\n\t" "\\var = -1\n\t" _IFC_REG(0) _IFC_REG(1) _IFC_REG(2) _IFC_REG(3) _IFC_REG(4) _IFC_REG(5) _IFC_REG(6) _IFC_REG(7) _IFC_REG(8) _IFC_REG(9) _IFC_REG(10) _IFC_REG(11) _IFC_REG(12) _IFC_REG(13) _IFC_REG(14) _IFC_REG(15) _IFC_REG(16) _IFC_REG(17) _IFC_REG(18) _IFC_REG(19) _IFC_REG(20) _IFC_REG(21) _IFC_REG(22) _IFC_REG(23) _IFC_REG(24) _IFC_REG(25) _IFC_REG(26) _IFC_REG(27) _IFC_REG(28) _IFC_REG(29) _IFC_REG(30) _IFC_REG(31) ".iflt \\var\n\t" ".error \"Unable to parse register name \\r\"\n\t" ".endif\n\t" ".endm")
dummy
int dummy
Definition: motion.c:64
MUL64
#define MUL64(a, b)
Definition: mathops.h:54
shift
static int shift(int a, int b)
Definition: sonic.c:82
int32_t
int32_t
Definition: audioconvert.c:56
MULL
#define MULL(a, b, s)
Definition: mathops.h:58