2 * CPU detection code, extracted from mmx.h
3 * (c)1997-99 by H. Dietz and R. Fisher
4 * Converted to C and improved by Fabrice Bellard.
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 #include "libavutil/x86_cpu.h"
26 #include "libavutil/cpu.h"
28 /* ebx saving is necessary for PIC. gcc seems unable to see it alone */
29 #define cpuid(index,eax,ebx,ecx,edx)\
31 ("mov %%"REG_b", %%"REG_S"\n\t"\
33 "xchg %%"REG_b", %%"REG_S\
34 : "=a" (eax), "=S" (ebx),\
35 "=c" (ecx), "=d" (edx)\
38 #define xgetbv(index,eax,edx) \
39 __asm__ (".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c" (index))
41 /* Function to test if multimedia instructions are supported... */
42 int ff_get_cpu_flags_x86(void)
45 int eax, ebx, ecx, edx;
46 int max_std_level, max_ext_level, std_caps=0, ext_caps=0;
47 int family=0, model=0;
48 union { int i[3]; char c[12]; } vendor;
53 /* See if CPUID instruction is supported ... */
54 /* ... Get copies of EFLAGS into eax and ecx */
59 /* ... Toggle the ID bit in one copy and store */
60 /* to the EFLAGS reg */
61 "xor $0x200000, %0\n\t"
65 /* ... Get the (hopefully modified) EFLAGS */
74 return 0; /* CPUID not supported */
77 cpuid(0, max_std_level, ebx, ecx, edx);
82 if(max_std_level >= 1){
83 cpuid(1, eax, ebx, ecx, std_caps);
84 family = ((eax>>8)&0xf) + ((eax>>20)&0xff);
85 model = ((eax>>4)&0xf) + ((eax>>12)&0xf0);
86 if (std_caps & (1<<15))
87 rval |= AV_CPU_FLAG_CMOV;
88 if (std_caps & (1<<23))
89 rval |= AV_CPU_FLAG_MMX;
90 if (std_caps & (1<<25))
91 rval |= AV_CPU_FLAG_MMX2
94 if (std_caps & (1<<26))
95 rval |= AV_CPU_FLAG_SSE2;
97 rval |= AV_CPU_FLAG_SSE3;
98 if (ecx & 0x00000200 )
99 rval |= AV_CPU_FLAG_SSSE3;
100 if (ecx & 0x00080000 )
101 rval |= AV_CPU_FLAG_SSE4;
102 if (ecx & 0x00100000 )
103 rval |= AV_CPU_FLAG_SSE42;
105 /* Check OXSAVE and AVX bits */
106 if ((ecx & 0x18000000) == 0x18000000) {
107 /* Check for OS support */
109 if ((eax & 0x6) == 0x6)
110 rval |= AV_CPU_FLAG_AVX;
117 cpuid(0x80000000, max_ext_level, ebx, ecx, edx);
119 if(max_ext_level >= 0x80000001){
120 cpuid(0x80000001, eax, ebx, ecx, ext_caps);
121 if (ext_caps & (1U<<31))
122 rval |= AV_CPU_FLAG_3DNOW;
123 if (ext_caps & (1<<30))
124 rval |= AV_CPU_FLAG_3DNOWEXT;
125 if (ext_caps & (1<<23))
126 rval |= AV_CPU_FLAG_MMX;
127 if (ext_caps & (1<<22))
128 rval |= AV_CPU_FLAG_MMX2;
130 /* Allow for selectively disabling SSE2 functions on AMD processors
131 with SSE2 support but not SSE4a. This includes Athlon64, some
132 Opteron, and some Sempron processors. MMX, SSE, or 3DNow! are faster
133 than SSE2 often enough to utilize this special-case flag.
134 AV_CPU_FLAG_SSE2 and AV_CPU_FLAG_SSE2SLOW are both set in this case
135 so that SSE2 is used unless explicitly disabled by checking
136 AV_CPU_FLAG_SSE2SLOW. */
137 if (!strncmp(vendor.c, "AuthenticAMD", 12) &&
138 rval & AV_CPU_FLAG_SSE2 && !(ecx & 0x00000040)) {
139 rval |= AV_CPU_FLAG_SSE2SLOW;
142 /* XOP and FMA4 use the AVX instruction coding scheme, so they can't be
143 * used unless the OS has AVX support. */
144 if (rval & AV_CPU_FLAG_AVX) {
145 if (ecx & 0x00000800)
146 rval |= AV_CPU_FLAG_XOP;
147 if (ecx & 0x00010000)
148 rval |= AV_CPU_FLAG_FMA4;
152 if (!strncmp(vendor.c, "GenuineIntel", 12)) {
153 if (family == 6 && (model == 9 || model == 13 || model == 14)) {
154 /* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and 6/14 (core1 "yonah")
155 * theoretically support sse2, but it's usually slower than mmx,
156 * so let's just pretend they don't. AV_CPU_FLAG_SSE2 is disabled and
157 * AV_CPU_FLAG_SSE2SLOW is enabled so that SSE2 is not used unless
158 * explicitly enabled by checking AV_CPU_FLAG_SSE2SLOW. The same
159 * situation applies for AV_CPU_FLAG_SSE3 and AV_CPU_FLAG_SSE3SLOW. */
160 if (rval & AV_CPU_FLAG_SSE2) rval ^= AV_CPU_FLAG_SSE2SLOW|AV_CPU_FLAG_SSE2;
161 if (rval & AV_CPU_FLAG_SSE3) rval ^= AV_CPU_FLAG_SSE3SLOW|AV_CPU_FLAG_SSE3;
163 /* The Atom processor has SSSE3 support, which is useful in many cases,
164 * but sometimes the SSSE3 version is slower than the SSE2 equivalent
165 * on the Atom, but is generally faster on other processors supporting
166 * SSSE3. This flag allows for selectively disabling certain SSSE3
167 * functions on the Atom. */
168 if (family == 6 && model == 28)
169 rval |= AV_CPU_FLAG_ATOM;