header.c

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#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../../util/header.h"

static inline void
cpuid(unsigned int op, unsigned int *a, unsigned int *b, unsigned int *c,
      unsigned int *d)
{
    __asm__ __volatile__ (".byte 0x53\n\tcpuid\n\t"
                  "movl %%ebx, %%esi\n\t.byte 0x5b"
            : "=a" (*a),
            "=S" (*b),
            "=c" (*c),
            "=d" (*d)
            : "a" (op));
}

int
get_cpuid(char *buffer, size_t sz)
{
    unsigned int a, b, c, d, lvl;
    int family = -1, model = -1, step = -1;
    int nb;
    char vendor[16];

    cpuid(0, &lvl, &b, &c, &d);
    strncpy(&vendor[0], (char *)(&b), 4);
    strncpy(&vendor[4], (char *)(&d), 4);
    strncpy(&vendor[8], (char *)(&c), 4);
    vendor[12] = '\0';

    if (lvl >= 1) {
        cpuid(1, &a, &b, &c, &d);

        family = (a >> 8) & 0xf;  /* bits 11 - 8 */
        model  = (a >> 4) & 0xf;  /* Bits  7 - 4 */
        step   = a & 0xf;

        /* extended family */
        if (family == 0xf)
            family += (a >> 20) & 0xff;

        /* extended model */
        if (family >= 0x6)
            model += ((a >> 16) & 0xf) << 4;
    }
    nb = scnprintf(buffer, sz, "%s,%u,%u,%u$", vendor, family, model, step);

    /* look for end marker to ensure the entire data fit */
    if (strchr(buffer, '$')) {
        buffer[nb-1] = '\0';
        return 0;
    }
    return -1;
}