godot/thirdparty/bullet/LinearMath/btCpuFeatureUtility.h

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#ifndef BT_CPU_UTILITY_H
#define BT_CPU_UTILITY_H
#include "LinearMath/btScalar.h"
#include <string.h> //memset
#ifdef USE_SIMD
#include <emmintrin.h>
#ifdef BT_ALLOW_SSE4
#include <intrin.h>
#endif //BT_ALLOW_SSE4
#endif //USE_SIMD
#if defined BT_USE_NEON
#define ARM_NEON_GCC_COMPATIBILITY 1
#include <arm_neon.h>
#include <sys/types.h>
#include <sys/sysctl.h> //for sysctlbyname
#endif //BT_USE_NEON
///Rudimentary btCpuFeatureUtility for CPU features: only report the features that Bullet actually uses (SSE4/FMA3, NEON_HPFP)
///We assume SSE2 in case BT_USE_SSE2 is defined in LinearMath/btScalar.h
class btCpuFeatureUtility
{
public:
enum btCpuFeature
{
CPU_FEATURE_FMA3 = 1,
CPU_FEATURE_SSE4_1 = 2,
CPU_FEATURE_NEON_HPFP = 4
};
static int getCpuFeatures()
{
static int capabilities = 0;
static bool testedCapabilities = false;
if (0 != testedCapabilities)
{
return capabilities;
}
#ifdef BT_USE_NEON
{
uint32_t hasFeature = 0;
size_t featureSize = sizeof(hasFeature);
int err = sysctlbyname("hw.optional.neon_hpfp", &hasFeature, &featureSize, NULL, 0);
if (0 == err && hasFeature)
capabilities |= CPU_FEATURE_NEON_HPFP;
}
#endif //BT_USE_NEON
#ifdef BT_ALLOW_SSE4
{
int cpuInfo[4];
memset(cpuInfo, 0, sizeof(cpuInfo));
unsigned long long sseExt = 0;
__cpuid(cpuInfo, 1);
bool osUsesXSAVE_XRSTORE = cpuInfo[2] & (1 << 27) || false;
bool cpuAVXSuport = cpuInfo[2] & (1 << 28) || false;
if (osUsesXSAVE_XRSTORE && cpuAVXSuport)
{
sseExt = _xgetbv(0);
}
const int OSXSAVEFlag = (1UL << 27);
const int AVXFlag = ((1UL << 28) | OSXSAVEFlag);
const int FMAFlag = ((1UL << 12) | AVXFlag | OSXSAVEFlag);
if ((cpuInfo[2] & FMAFlag) == FMAFlag && (sseExt & 6) == 6)
{
capabilities |= btCpuFeatureUtility::CPU_FEATURE_FMA3;
}
const int SSE41Flag = (1 << 19);
if (cpuInfo[2] & SSE41Flag)
{
capabilities |= btCpuFeatureUtility::CPU_FEATURE_SSE4_1;
}
}
#endif //BT_ALLOW_SSE4
testedCapabilities = true;
return capabilities;
}
};
#endif //BT_CPU_UTILITY_H