mirror of https://git.ffmpeg.org/ffmpeg.git
172 lines
6.4 KiB
C
172 lines
6.4 KiB
C
/*
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* CPU detection code, extracted from mmx.h
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* (c)1997-99 by H. Dietz and R. Fisher
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* Converted to C and improved by Fabrice Bellard.
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "libavutil/x86_cpu.h"
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#include "libavutil/cpu.h"
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/* ebx saving is necessary for PIC. gcc seems unable to see it alone */
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#define cpuid(index, eax, ebx, ecx, edx) \
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__asm__ volatile ( \
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"mov %%"REG_b", %%"REG_S" \n\t" \
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"cpuid \n\t" \
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"xchg %%"REG_b", %%"REG_S \
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: "=a" (eax), "=S" (ebx), "=c" (ecx), "=d" (edx) \
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: "0" (index))
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#define xgetbv(index, eax, edx) \
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__asm__ (".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c" (index))
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#define get_eflags(x) \
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__asm__ volatile ("pushfl \n" \
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"pop %0 \n" \
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: "=r"(x))
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#define set_eflags(x) \
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__asm__ volatile ("push %0 \n" \
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"popfl \n" \
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:: "r"(x))
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/* Function to test if multimedia instructions are supported... */
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int ff_get_cpu_flags_x86(void)
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{
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int rval = 0;
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int eax, ebx, ecx, edx;
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int max_std_level, max_ext_level, std_caps = 0, ext_caps = 0;
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int family = 0, model = 0;
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union { int i[3]; char c[12]; } vendor;
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#if ARCH_X86_32
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x86_reg a, c;
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/* Check if CPUID is supported by attempting to toggle the ID bit in
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* the EFLAGS register. */
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get_eflags(a);
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set_eflags(a ^ 0x200000);
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get_eflags(c);
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if (a == c)
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return 0; /* CPUID not supported */
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#endif
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cpuid(0, max_std_level, ebx, ecx, edx);
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vendor.i[0] = ebx;
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vendor.i[1] = edx;
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vendor.i[2] = ecx;
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if (max_std_level >= 1) {
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cpuid(1, eax, ebx, ecx, std_caps);
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family = ((eax >> 8) & 0xf) + ((eax >> 20) & 0xff);
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model = ((eax >> 4) & 0xf) + ((eax >> 12) & 0xf0);
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if (std_caps & (1 << 15))
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rval |= AV_CPU_FLAG_CMOV;
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if (std_caps & (1 << 23))
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rval |= AV_CPU_FLAG_MMX;
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if (std_caps & (1 << 25))
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rval |= AV_CPU_FLAG_MMX2;
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#if HAVE_SSE
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if (std_caps & (1 << 25))
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rval |= AV_CPU_FLAG_SSE;
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if (std_caps & (1 << 26))
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rval |= AV_CPU_FLAG_SSE2;
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if (ecx & 1)
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rval |= AV_CPU_FLAG_SSE3;
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if (ecx & 0x00000200 )
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rval |= AV_CPU_FLAG_SSSE3;
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if (ecx & 0x00080000 )
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rval |= AV_CPU_FLAG_SSE4;
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if (ecx & 0x00100000 )
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rval |= AV_CPU_FLAG_SSE42;
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#if HAVE_AVX
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/* Check OXSAVE and AVX bits */
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if ((ecx & 0x18000000) == 0x18000000) {
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/* Check for OS support */
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xgetbv(0, eax, edx);
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if ((eax & 0x6) == 0x6)
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rval |= AV_CPU_FLAG_AVX;
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}
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#endif
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#endif
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}
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cpuid(0x80000000, max_ext_level, ebx, ecx, edx);
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if (max_ext_level >= 0x80000001) {
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cpuid(0x80000001, eax, ebx, ecx, ext_caps);
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if (ext_caps & (1U << 31))
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rval |= AV_CPU_FLAG_3DNOW;
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if (ext_caps & (1 << 30))
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rval |= AV_CPU_FLAG_3DNOWEXT;
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if (ext_caps & (1 << 23))
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rval |= AV_CPU_FLAG_MMX;
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if (ext_caps & (1 << 22))
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rval |= AV_CPU_FLAG_MMX2;
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/* Allow for selectively disabling SSE2 functions on AMD processors
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with SSE2 support but not SSE4a. This includes Athlon64, some
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Opteron, and some Sempron processors. MMX, SSE, or 3DNow! are faster
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than SSE2 often enough to utilize this special-case flag.
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AV_CPU_FLAG_SSE2 and AV_CPU_FLAG_SSE2SLOW are both set in this case
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so that SSE2 is used unless explicitly disabled by checking
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AV_CPU_FLAG_SSE2SLOW. */
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if (!strncmp(vendor.c, "AuthenticAMD", 12) &&
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rval & AV_CPU_FLAG_SSE2 && !(ecx & 0x00000040)) {
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rval |= AV_CPU_FLAG_SSE2SLOW;
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}
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/* XOP and FMA4 use the AVX instruction coding scheme, so they can't be
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* used unless the OS has AVX support. */
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if (rval & AV_CPU_FLAG_AVX) {
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if (ecx & 0x00000800)
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rval |= AV_CPU_FLAG_XOP;
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if (ecx & 0x00010000)
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rval |= AV_CPU_FLAG_FMA4;
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}
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}
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if (!strncmp(vendor.c, "GenuineIntel", 12)) {
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if (family == 6 && (model == 9 || model == 13 || model == 14)) {
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/* 6/9 (pentium-m "banias"), 6/13 (pentium-m "dothan"), and
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* 6/14 (core1 "yonah") theoretically support sse2, but it's
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* usually slower than mmx, so let's just pretend they don't.
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* AV_CPU_FLAG_SSE2 is disabled and AV_CPU_FLAG_SSE2SLOW is
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* enabled so that SSE2 is not used unless explicitly enabled
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* by checking AV_CPU_FLAG_SSE2SLOW. The same situation
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* applies for AV_CPU_FLAG_SSE3 and AV_CPU_FLAG_SSE3SLOW. */
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if (rval & AV_CPU_FLAG_SSE2)
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rval ^= AV_CPU_FLAG_SSE2SLOW | AV_CPU_FLAG_SSE2;
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if (rval & AV_CPU_FLAG_SSE3)
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rval ^= AV_CPU_FLAG_SSE3SLOW | AV_CPU_FLAG_SSE3;
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}
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/* The Atom processor has SSSE3 support, which is useful in many cases,
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* but sometimes the SSSE3 version is slower than the SSE2 equivalent
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* on the Atom, but is generally faster on other processors supporting
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* SSSE3. This flag allows for selectively disabling certain SSSE3
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* functions on the Atom. */
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if (family == 6 && model == 28)
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rval |= AV_CPU_FLAG_ATOM;
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}
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return rval;
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}
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