Código para parsear la salida del comando cpuid y determinar las capacidades del procesador.

cpuid.c

#include <stdio.h>
#define HT_FLAG		0x10000000
#define SSE_FLAG 	0x02000000
#define SSE2_FLAG	0x04000000
#define SSSE3_FLAG	0x00000200
#define SSE4_1_FLAG	0x00080000
#define SSE4_2_FLAG	0x00100000

void cpuid(unsigned info, unsigned *eax, unsigned *ebx, unsigned *ecx, unsigned *edx) 
{
    *eax = info;
    asm volatile(
        "mov %%ebx, %%edi;"
        "cpuid;"
        "mov %%ebx, %%esi;"
        "mov %%edi, %%ebx;"
        :"+a" (*eax), "=S" (*ebx), "=c" (*ecx), "=d" (*edx)
        : :"edi");
}
  
void cpuid_parse(char *buf)
{
    unsigned eax, ebx, ecx, edx;
    int i=0;
    cpuid(1, &eax, &ebx, &ecx, &edx);
    i+=sprintf(buf+i, "CPUID Features(EAX=1): ECX=0x%08x EDX=0x%08x\n", ecx, edx);
    if (edx & HT_FLAG) i+=sprintf(buf+i, "HT: YES\n"); else i+=sprintf(buf+i, "HT: NO\n");
    if (edx & SSE_FLAG) i+=sprintf(buf+i, "SSE: YES\n"); else i+=sprintf(buf+i, "SSE: NO\n");
    if (edx & SSE2_FLAG) i+=sprintf(buf+i, "SSE2: YES\n"); else i+=sprintf(buf+i, "SSE2: NO\n");
    if (ecx & SSSE3_FLAG) i+=sprintf(buf+i, "SSSE3: YES\n"); else i+=sprintf(buf+i, "SSE3: NO\n");
    if (ecx & SSE4_1_FLAG) i+=sprintf(buf+i, "SSE4_1: YES\n"); else i+=sprintf(buf+i, "SSE4_1: NO\n");
    if (ecx & SSE4_2_FLAG) i+=sprintf(buf+i, "SSE4_2: YES\n"); else i+=sprintf(buf+i, "SSE4_2: NO\n");

}