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113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/*
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* x86 feature check
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*
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* Copyright (C) 2013 Intel Corporation. All rights reserved.
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* Author:
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* Jim Kukunas
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*
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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#include "x86.h"
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int x86_cpu_enable_simd = 0;
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#ifndef _MSC_VER
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#include <pthread.h>
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pthread_once_t cpu_check_inited_once = PTHREAD_ONCE_INIT;
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static void _x86_check_features(void);
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void x86_check_features(void)
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{
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pthread_once(&cpu_check_inited_once, _x86_check_features);
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}
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static void _x86_check_features(void)
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{
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int x86_cpu_has_sse2;
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int x86_cpu_has_sse42;
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int x86_cpu_has_pclmulqdq;
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unsigned eax, ebx, ecx, edx;
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eax = 1;
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#ifdef __i386__
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__asm__ __volatile__ (
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"xchg %%ebx, %1\n\t"
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"cpuid\n\t"
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"xchg %1, %%ebx\n\t"
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: "+a" (eax), "=S" (ebx), "=c" (ecx), "=d" (edx)
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);
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#else
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__asm__ __volatile__ (
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"cpuid\n\t"
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: "+a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
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);
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#endif /* (__i386__) */
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x86_cpu_has_sse2 = edx & 0x4000000;
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x86_cpu_has_sse42 = ecx & 0x100000;
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x86_cpu_has_pclmulqdq = ecx & 0x2;
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x86_cpu_enable_simd = x86_cpu_has_sse2 &&
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x86_cpu_has_sse42 &&
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x86_cpu_has_pclmulqdq;
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}
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#else
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#include <intrin.h>
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#include <windows.h>
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#include <stdint.h>
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static volatile int32_t once_control = 0;
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static void _x86_check_features(void);
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static int fake_pthread_once(volatile int32_t *once_control,
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void (*init_routine)(void));
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void x86_check_features(void)
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{
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fake_pthread_once(&once_control, _x86_check_features);
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}
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/* Copied from "perftools_pthread_once" in tcmalloc */
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static int fake_pthread_once(volatile int32_t *once_control,
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void (*init_routine)(void)) {
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// Try for a fast path first. Note: this should be an acquire semantics read
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// It is on x86 and x64, where Windows runs.
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if (*once_control != 1) {
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while (1) {
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switch (InterlockedCompareExchange(once_control, 2, 0)) {
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case 0:
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init_routine();
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InterlockedExchange(once_control, 1);
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return 0;
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case 1:
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// The initializer has already been executed
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return 0;
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default:
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// The initializer is being processed by another thread
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SwitchToThread();
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}
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}
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}
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return 0;
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}
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static void _x86_check_features(void)
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{
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int x86_cpu_has_sse2;
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int x86_cpu_has_sse42;
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int x86_cpu_has_pclmulqdq;
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int regs[4];
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__cpuid(regs, 1);
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x86_cpu_has_sse2 = regs[3] & 0x4000000;
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x86_cpu_has_sse42= regs[2] & 0x100000;
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x86_cpu_has_pclmulqdq = regs[2] & 0x2;
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x86_cpu_enable_simd = x86_cpu_has_sse2 &&
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x86_cpu_has_sse42 &&
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x86_cpu_has_pclmulqdq;
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}
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#endif /* _MSC_VER */
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