libavcodec/i386/cputest.c

   1 /* Cpu detection code, extracted from mmx.h ((c)1997-99 by H. Dietz
   2    and R. Fisher). Converted to C and improved by Gerard Lantau */
   3
   4 #include <stdlib.h>
   5 #include "../dsputil.h"
   6
   7 /* ebx saving is necessary for PIC. gcc seems unable to see it alone */
   8 static inline void cpuid(int index, int *eax, int *ebx, int *ecx, int *edx)
   9 {
  10     asm ("pushl %%ebx\n\t"
  11          "cpuid\n\t"
  12          "movl %%ebx, %1\n\t"
  13          "popl %%ebx\n\t"
  14          : "=a" (*eax), "=m" (*ebx),
  15            "=c" (*ecx), "=d" (*edx)
  16          : "a" (index)
  17          : "cc");
  18 }
  19
  20 /* Function to test if multimedia instructions are supported...  */
  21 int mm_support(void)
  22 {
  23     int rval;
  24     int eax, ebx, ecx, edx;
  25
  26     __asm__ __volatile__ (
  27                           /* See if CPUID instruction is supported ... */
  28                           /* ... Get copies of EFLAGS into eax and ecx */
  29                           "pushf\n\t"
  30                           "popl %0\n\t"
  31                           "movl %0, %1\n\t"
  32
  33                           /* ... Toggle the ID bit in one copy and store */
  34                           /*     to the EFLAGS reg */
  35                           "xorl $0x200000, %0\n\t"
  36                           "push %0\n\t"
  37                           "popf\n\t"
  38
  39                           /* ... Get the (hopefully modified) EFLAGS */
  40                           "pushf\n\t"
  41                           "popl %0\n\t"
  42                           : "=a" (eax), "=c" (ecx)
  43                           :
  44                           : "cc"
  45                           );
  46
  47     if (eax == ecx)
  48         return 0; /* CPUID not supported */
  49
  50     cpuid(0, &eax, &ebx, &ecx, &edx);
  51
  52     if (ebx == 0x756e6547 &&
  53         edx == 0x49656e69 &&
  54         ecx == 0x6c65746e) {
  55
  56         /* intel */
  57     inteltest:
  58         cpuid(1, &eax, &ebx, &ecx, &edx);
  59         if ((edx & 0x00800000) == 0)
  60             return 0;
  61         rval = MM_MMX;
  62         if (edx & 0x02000000)
  63             rval |= MM_MMXEXT | MM_SSE;
  64         if (edx & 0x04000000)
  65             rval |= MM_SSE2;
  66         return rval;
  67     } else if (ebx == 0x68747541 &&
  68                edx == 0x69746e65 &&
  69                ecx == 0x444d4163) {
  70         /* AMD */
  71         cpuid(0x80000000, &eax, &ebx, &ecx, &edx);
  72         if ((unsigned)eax < 0x80000001)
  73             goto inteltest;
  74         cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
  75         if ((edx & 0x00800000) == 0)
  76             return 0;
  77         rval = MM_MMX;
  78         if (edx & 0x80000000)
  79             rval |= MM_3DNOW;
  80         if (edx & 0x00400000)
  81             rval |= MM_MMXEXT;
  82         return rval;
  83     } else if (ebx == 0x69727943 &&
  84                edx == 0x736e4978 &&
  85                ecx == 0x64616574) {
  86         /* Cyrix Section */
  87         /* See if extended CPUID level 80000001 is supported */
  88         /* The value of CPUID/80000001 for the 6x86MX is undefined
  89            according to the Cyrix CPU Detection Guide (Preliminary
  90            Rev. 1.01 table 1), so we'll check the value of eax for
  91            CPUID/0 to see if standard CPUID level 2 is supported.
  92            According to the table, the only CPU which supports level
  93            2 is also the only one which supports extended CPUID levels.
  94         */
  95         if (eax != 2)
  96             goto inteltest;
  97         cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
  98         if ((eax & 0x00800000) == 0)
  99             return 0;
 100         rval = MM_MMX;
 101         if (eax & 0x01000000)
 102             rval |= MM_MMXEXT;
 103         return rval;
 104     } else {
 105         return 0;
 106     }
 107 }