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mpv/cpudetect.c

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#include "config.h"
#include "cpudetect.h"
#ifdef ARCH_X86
#include <stdio.h>
#ifdef __FreeBSD__
#include <sys/types.h>
#include <sys/sysctl.h>
#endif
#ifdef __linux__
#include <signal.h>
#endif
//#define X86_FXSR_MAGIC
/* Thanks to the FreeBSD project for some of this cpuid code, and
* help understanding how to use it. Thanks to the Mesa
* team for SSE support detection and more cpu detect code.
*/
/* I believe this code works. However, it has only been used on a PII and PIII */
CpuCaps gCpuCaps;
static void check_os_katmai_support( void );
#if 1
// return TRUE if cpuid supported
static int has_cpuid()
{
int a, c;
// code from libavcodec:
__asm__ __volatile__ (
/* See if CPUID instruction is supported ... */
/* ... Get copies of EFLAGS into eax and ecx */
"pushf\n\t"
"popl %0\n\t"
"movl %0, %1\n\t"
/* ... Toggle the ID bit in one copy and store */
/* to the EFLAGS reg */
"xorl $0x200000, %0\n\t"
"push %0\n\t"
"popf\n\t"
/* ... Get the (hopefully modified) EFLAGS */
"pushf\n\t"
"popl %0\n\t"
: "=a" (a), "=c" (c)
:
: "cc"
);
return (a!=c);
}
#endif
static void
do_cpuid(unsigned int ax, unsigned int *p)
{
#if 0
__asm __volatile(
"cpuid;"
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax)
);
#else
// code from libavcodec:
__asm __volatile
("movl %%ebx, %%esi\n\t"
"cpuid\n\t"
"xchgl %%ebx, %%esi"
: "=a" (p[0]), "=S" (p[1]),
"=c" (p[2]), "=d" (p[3])
: "0" (ax));
#endif
}
void GetCpuCaps( CpuCaps *caps)
{
unsigned int regs[4];
unsigned int regs2[4];
bzero(caps, sizeof(*caps));
printf("CPUid available: %s\n",has_cpuid()?"yes":"no");
/*if (!has_cpuid())
return;*/
do_cpuid(0x00000000, regs);
printf("CPU vendor name: %.4s%.4s%.4s\n",&regs[1],&regs[3],&regs[2]);
if (regs[0]>0x00000001) {
do_cpuid(0x00000001, regs2);
printf("CPU family: %d\n",(regs2[0] >> 8)&0xf);
switch ((regs2[0] >> 8)&0xf) {
case 3:
caps->cpuType=CPUTYPE_I386;
break;
case 4:
caps->cpuType=CPUTYPE_I486;
break;
case 5:
caps->cpuType=CPUTYPE_I586;
break;
case 6:
caps->cpuType=CPUTYPE_I586;
break;
default:
printf("Unknown cpu type, default to i386\n");
break;
}
caps->hasMMX = (regs2[3] & (1 << 23 )) >> 23; // 0x0800000
// FIXME: is this ok for non-intel CPUs too? (cyrix,amd)
caps->hasSSE = (regs2[3] & (1 << 25 )) >> 25; // 0x2000000
caps->hasSSE2 = (regs2[3] & (1 << 26 )) >> 26; // 0x4000000
/* FIXME: Does SSE2 need more OS support, too? */
#if defined(__linux__) || defined(__FreeBSD__)
if (caps->hasSSE)
check_os_katmai_support();
if (!caps->hasSSE)
caps->hasSSE2 = 0;
#else
caps->hasSSE=0;
caps->hasSSE2 = 0;
#endif
/* FIXME: Are MMX2 ops on the same set of processors as SSE? Do they need OS support?*/
caps->hasMMX2 = caps->hasSSE;
}
if (regs[1] == 0x68747541 && // AuthenticAMD
regs[3] == 0x69746e65 &&
regs[2] == 0x444d4163) {
do_cpuid(0x80000000, regs);
if (regs[0]>=0x80000001) {
do_cpuid(0x80000001, regs2);
caps->hasMMX2 = (regs[3] & (1 << 22 )) >> 22; // 0x400000
caps->has3DNow = (regs2[3] & (1 << 31 )) >> 31; //0x80000000
caps->has3DNowExt = (regs2[3] & (1 << 30 )) >> 30;
}
}
#if 0
printf("cpudetect: MMX=%d MMX2=%d SSE=%d SSE2=%d 3DNow=%d 3DNowExt=%d\n",
gCpuCaps.hasMMX,
gCpuCaps.hasMMX2,
gCpuCaps.hasSSE,
gCpuCaps.hasSSE2,
gCpuCaps.has3DNow,
gCpuCaps.has3DNowExt );
#endif
}
#if defined(__linux__) && defined(_POSIX_SOURCE) && defined(X86_FXSR_MAGIC)
static void sigill_handler_sse( int signal, struct sigcontext sc )
{
printf( "SIGILL, " );
/* Both the "xorps %%xmm0,%%xmm0" and "divps %xmm0,%%xmm1"
* instructions are 3 bytes long. We must increment the instruction
* pointer manually to avoid repeated execution of the offending
* instruction.
*
* If the SIGILL is caused by a divide-by-zero when unmasked
* exceptions aren't supported, the SIMD FPU status and control
* word will be restored at the end of the test, so we don't need
* to worry about doing it here. Besides, we may not be able to...
*/
sc.eip += 3;
gCpuCaps.hasSSE=0;
}
static void sigfpe_handler_sse( int signal, struct sigcontext sc )
{
printf( "SIGFPE, " );
if ( sc.fpstate->magic != 0xffff ) {
/* Our signal context has the extended FPU state, so reset the
* divide-by-zero exception mask and clear the divide-by-zero
* exception bit.
*/
sc.fpstate->mxcsr |= 0x00000200;
sc.fpstate->mxcsr &= 0xfffffffb;
} else {
/* If we ever get here, we're completely hosed.
*/
printf( "\n\n" );
printf( "SSE enabling test failed badly!" );
}
}
#endif /* __linux__ && _POSIX_SOURCE && X86_FXSR_MAGIC */
/* If we're running on a processor that can do SSE, let's see if we
* are allowed to or not. This will catch 2.4.0 or later kernels that
* haven't been configured for a Pentium III but are running on one,
* and RedHat patched 2.2 kernels that have broken exception handling
* support for user space apps that do SSE.
*/
static void check_os_katmai_support( void )
{
#if defined(__FreeBSD__)
int has_sse=0, ret;
size_t len=sizeof(has_sse);
ret = sysctlbyname("hw.instruction_sse", &has_sse, &len, NULL, 0);
if (ret || !has_sse)
gCpuCaps.hasSSE=0;
#elif defined(__linux__)
#if defined(_POSIX_SOURCE) && defined(X86_FXSR_MAGIC)
struct sigaction saved_sigill;
struct sigaction saved_sigfpe;
/* Save the original signal handlers.
*/
sigaction( SIGILL, NULL, &saved_sigill );
sigaction( SIGFPE, NULL, &saved_sigfpe );
signal( SIGILL, (void (*)(int))sigill_handler_sse );
signal( SIGFPE, (void (*)(int))sigfpe_handler_sse );
/* Emulate test for OSFXSR in CR4. The OS will set this bit if it
* supports the extended FPU save and restore required for SSE. If
* we execute an SSE instruction on a PIII and get a SIGILL, the OS
* doesn't support Streaming SIMD Exceptions, even if the processor
* does.
*/
if ( gCpuCaps.hasSSE ) {
printf( "Testing OS support for SSE... " );
// __asm __volatile ("xorps %%xmm0, %%xmm0");
__asm __volatile ("xorps %xmm0, %xmm0");
if ( gCpuCaps.hasSSE ) {
printf( "yes.\n" );
} else {
printf( "no!\n" );
}
}
/* Emulate test for OSXMMEXCPT in CR4. The OS will set this bit if
* it supports unmasked SIMD FPU exceptions. If we unmask the
* exceptions, do a SIMD divide-by-zero and get a SIGILL, the OS
* doesn't support unmasked SIMD FPU exceptions. If we get a SIGFPE
* as expected, we're okay but we need to clean up after it.
*
* Are we being too stringent in our requirement that the OS support
* unmasked exceptions? Certain RedHat 2.2 kernels enable SSE by
* setting CR4.OSFXSR but don't support unmasked exceptions. Win98
* doesn't even support them. We at least know the user-space SSE
* support is good in kernels that do support unmasked exceptions,
* and therefore to be safe I'm going to leave this test in here.
*/
if ( gCpuCaps.hasSSE ) {
printf( "Testing OS support for SSE unmasked exceptions... " );
// test_os_katmai_exception_support();
if ( gCpuCaps.hasSSE ) {
printf( "yes.\n" );
} else {
printf( "no!\n" );
}
}
/* Restore the original signal handlers.
*/
sigaction( SIGILL, &saved_sigill, NULL );
sigaction( SIGFPE, &saved_sigfpe, NULL );
/* If we've gotten to here and the XMM CPUID bit is still set, we're
* safe to go ahead and hook out the SSE code throughout Mesa.
*/
if ( gCpuCaps.hasSSE ) {
printf( "Tests of OS support for SSE passed.\n" );
} else {
printf( "Tests of OS support for SSE failed!\n" );
}
#else
/* We can't use POSIX signal handling to test the availability of
* SSE, so we disable it by default.
*/
printf( "Cannot test OS support for SSE, disabling to be safe.\n" );
gCpuCaps.hasSSE=0;
#endif /* _POSIX_SOURCE && X86_FXSR_MAGIC */
#else
/* Do nothing on other platforms for now.
*/
message( "Not testing OS support for SSE, leaving disabled.\n" );
gCpuCaps.hasSSE=0;
#endif /* __linux__ */
}
#endif /* ARCH_X86 */
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