x86-64 registers structure definition

x86_64_regs.c

#include <stdint.h>
#include <stddef.h>
#include <stdio.h>

#define __packed  __attribute__((packed))

/* https://commons.wikimedia.org/wiki/File:Table_of_x86_Registers_svg.svg */

#define REGDEF_hl(Z)   \
    union __packed {        \
        uint64_t r##Z##x;   \
        uint32_t e##Z##x;   \
        uint16_t Z##x;      \
        struct __packed {   \
            uint8_t Z##l;   \
            uint8_t Z##h;   \
        };                  \
    }

#define REGDEF_l(Z)  \
    union __packed {        \
        uint64_t r##Z;      \
        uint32_t e##Z;      \
        uint16_t Z;         \
        uint8_t  Z##l;      \
    }

#define REGDEF_nol(Z)  \
    union __packed {        \
        uint64_t r##Z;      \
        uint32_t e##Z;      \
        uint16_t Z;         \
    }

#define REGDEF_bwd(Z)  \
    union __packed {        \
        uint64_t r##Z;      \
        uint32_t r##Z##d;   \
        uint16_t r##Z##w;   \
        uint8_t  r##Z##b;   \
    }

struct uc_x86_state {
    REGDEF_hl(a);
    REGDEF_hl(b);
    REGDEF_hl(c);
    REGDEF_hl(d);

    REGDEF_l(sp);
    REGDEF_l(bp);
    REGDEF_l(si);
    REGDEF_l(di);

    REGDEF_bwd(8);
    REGDEF_bwd(9);
    REGDEF_bwd(10);
    REGDEF_bwd(11);
    REGDEF_bwd(12);
    REGDEF_bwd(13);
    REGDEF_bwd(14);
    REGDEF_bwd(15);

    REGDEF_nol(ip);
    REGDEF_nol(flags);
};

#undef REGDEF_hl
#undef REGDEF_l
#undef REGDEF_bwd
#undef REGDEF_nol



#define pr(x)   printf("offset of " #x ": 0x%lX\n", offsetof(struct uc_x86_state, x))

int main(void)
{
    pr(rax);
    pr(eax);
    pr(ax);
    pr(al);
    pr(ah);

    __asm("mov %rsp,%rax\n");
    __asm("mov %esp,%eax\n");
    __asm("mov %sp,%ax\n");
    __asm("mov %spl,%al\n");    /* I didn't even know this existed */

    return 0;
}