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