cpu_capabilities (3) - Linux Manuals

cpu_capabilities: Contains the capability flags of the CPU. Allegro game programming library.

NAME

cpu_capabilities - Contains the capability flags of the CPU. Allegro game programming library.

SYNOPSIS

#include <allegro.h>

extern int cpu_capabilities;

DESCRIPTION

Contains CPU flags indicating what features are available on the current CPU. The flags can be any combination of these:

   CPU_ID       - Indicates that the "cpuid" instruction is
                  available. If this is set, then all Allegro CPU
                  variables are 100% reliable, otherwise there
                  may be some mistakes.
   CPU_FPU      - An FPU is available.
   CPU_IA64     - Running on Intel 64 bit CPU
   CPU_AMD64    - Running on AMD 64 bit CPU
   CPU_MMX      - Intel MMX  instruction set is available.
   CPU_MMXPLUS  - Intel MMX+ instruction set is available.
   CPU_SSE      - Intel SSE  instruction set is available.
   CPU_SSE2     - Intel SSE2 instruction set is available.
   CPU_SSE3     - Intel SSE3 instruction set is available.
   CPU_3DNOW    - AMD 3DNow! instruction set is available.
   CPU_ENH3DNOW - AMD Enhanced 3DNow! instruction set is
                  available.
   CPU_CMOV     - Pentium Pro "cmov" instruction is available.
   

You can check for multiple features by OR-ing the flags together. For example, to check if the CPU has an FPU and MMX instructions available, you'd do:

   if ((cpu_capabilities & (CPU_FPU | CPU_MMX)) ==
       (CPU_FPU | CPU_MMX)) {
      printf("CPU has both an FPU and MMX instructions!\n");
   }
   

You can read this variable after you have called check_cpu() (which is automatically called by allegro_init()).