Core: Rewrite CPUID to preserve EBX register (Fix #73)

Former-commit-id: 19651c4e8856df2e6a9a208b5dfab1dfdde80978 [formerly d7392176b9b510939aeefaf5c853d023af211379] [formerly 36c14e52fae5966508143704557610247aaf2e22 [formerly 1901b3100ddc4621685375de77dfb7863687d1b4]]
Former-commit-id: 53af7fc2cb9ee97f16cc03db53658385dc218b71 [formerly d43f598f33684430ab3a58db1533cb108be6e26a]
Former-commit-id: 5d88e9b7ef4bc7e05060ac06678d6c141d9a88a4

src/Nazara/Core/Posix/HardwareInfoImpl.cpp

@@ -11,10 +11,22 @@ namespace Nz
 	void HardwareInfoImpl::Cpuid(UInt32 functionId, UInt32 subFunctionId, UInt32 registers[4])
 	{
 	#if defined(NAZARA_COMPILER_CLANG) || defined(NAZARA_COMPILER_GCC) || defined(NAZARA_COMPILER_INTEL)
-		// Source: http://stackoverflow.com/questions/1666093/cpuid-implementations-in-c
+		// https://en.wikipedia.org/wiki/CPUID
-		asm volatile ("cpuid" // Besoin d'être volatile ?
+		asm volatile(
-					  : "=a" (registers[0]), "=b" (registers[1]), "=c" (registers[2]), "=d" (registers[3]) // output
+			#ifdef NAZARA_PLATFORM_x64
-					  : "a" (functionId), "c" (subFunctionId));                                // input
+			"pushq %%rbx     \n\t" // save %rbx
+			#else
+			"pushl %%ebx     \n\t" // save %ebx
+			#endif
+			"cpuid            \n\t"
+			"movl %%ebx ,%[ebx]  \n\t" // write the result into output var
+			#ifdef NAZARA_PLATFORM_x64
+			"popq %%rbx \n\t"
+			#else
+			"popl %%ebx \n\t"
+			#endif
+			: "=a"(registers[0]), [ebx] "=r"(registers[1]), "=c"(registers[2]), "=d"(registers[3])
+			: "a"(functionId), "c" (subFunctionId));
 	#else
 		NazaraInternalError("Cpuid has been called although it is not supported");
 	#endif
@@ -22,7 +34,7 @@ namespace Nz
 
 	unsigned int HardwareInfoImpl::GetProcessorCount()
 	{
-		// Plus simple (et plus portable) que de passer par le CPUID
+		// Simpler (and more portable) than using CPUID
 		return sysconf(_SC_NPROCESSORS_CONF);
 	}
 
@@ -37,7 +49,7 @@ namespace Nz
 	bool HardwareInfoImpl::IsCpuidSupported()
 	{
 	#ifdef NAZARA_PLATFORM_x64
-		return true; // Toujours supporté sur un processeur 64 bits
+		return true; // cpuid is always supported on x64 arch
 	#else
 		#if defined(NAZARA_COMPILER_CLANG) || defined(NAZARA_COMPILER_GCC) || defined(NAZARA_COMPILER_INTEL)
 		int supported;

src/Nazara/Core/Win32/HardwareInfoImpl.cpp

@@ -22,10 +22,22 @@ namespace Nz
 		// Visual propose une fonction intrinsèque pour le cpuid
 		__cpuidex(reinterpret_cast<int*>(registers), static_cast<int>(functionId), static_cast<int>(subFunctionId));
 	#elif defined(NAZARA_COMPILER_CLANG) || defined(NAZARA_COMPILER_GCC) || defined(NAZARA_COMPILER_INTEL)
-		// Source: http://stackoverflow.com/questions/1666093/cpuid-implementations-in-c
+		// https://en.wikipedia.org/wiki/CPUID
-		asm volatile ("cpuid" // Besoin d'être volatile ?
+		asm volatile(
-					  : "=a" (registers[0]), "=b" (registers[1]), "=c" (registers[2]), "=d" (registers[3]) // output
+			#ifdef NAZARA_PLATFORM_x64
-					  : "a" (functionId), "c" (subFunctionId));                                // input
+			"pushq %%rbx     \n\t" // save %rbx
+			#else
+			"pushl %%ebx     \n\t" // save %ebx
+			#endif
+			"cpuid            \n\t"
+			"movl %%ebx ,%[ebx]  \n\t" // write the result into output var
+			#ifdef NAZARA_PLATFORM_x64
+			"popq %%rbx \n\t"
+			#else
+			"popl %%ebx \n\t"
+			#endif
+			: "=a"(registers[0]), [ebx] "=r"(registers[1]), "=c"(registers[2]), "=d"(registers[3]) // output
+			: "a"(functionId), "c" (subFunctionId));                                               // input
 	#else
 		NazaraInternalError("Cpuid has been called although it is not supported");
 	#endif
@@ -33,7 +45,7 @@ namespace Nz
 
 	unsigned int HardwareInfoImpl::GetProcessorCount()
 	{
-		// Plus simple (et plus portable) que de passer par le CPUID
+		// Simpler (and more portable) than using CPUID
 		SYSTEM_INFO infos;
 		GetNativeSystemInfo(&infos);
 
@@ -52,7 +64,7 @@ namespace Nz
 	bool HardwareInfoImpl::IsCpuidSupported()
 	{
 	#ifdef NAZARA_PLATFORM_x64
-		return true; // Toujours supporté sur un processeur 64 bits
+		return true; // cpuid is always supported on x64 arch
 	#else
 		#if defined(NAZARA_COMPILER_MSVC)
 		int supported;