assembly 在汇编指令中添加变量(asm inline C示例)

kxkpmulp 于 2022-11-13 发布在其他

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我想执行asm行代码的循环。实际上我正在尝试读取我的核心的CPUID，需要读取CPUID的所有参数。如果我将0写入eax寄存器，然后我会得到制造商名称，如果我写1到eax，那么下一组CPUID信息将会收到。等等...现在，我想执行多达15组asm指令，以获得完整的CPUID输出。
例如：

unsigned int cpuid_reg[4];

        __asm__ volatile("mov $1, %eax");
        __asm__ volatile("cpuid" : "=a" (cpuid_reg[0]), "=b" (cpuid_reg[1]), "=c" (cpuid_reg[2]), "=d" (cpuid_reg[3]));
        printf("reg[0] 0x%x , cpuid_reg[1] 0x%x, cpuid_reg[2] 0x%x, cpuid_reg[3] 0x%x\n", cpuid_reg[0], cpuid_reg[1], cpuid_reg[2], cpuid_reg[3]);

        __asm__ volatile("mov $2, %eax");
        __asm__ volatile("cpuid" : "=a" (cpuid_reg[0]), "=b" (cpuid_reg[1]), "=c" (cpuid_reg[2]), "=d" (cpuid_reg[3]));
        printf("cpuid_reg[0] 0x%x , cpuid_reg[1] 0x%x, cpuid_reg[2] 0x%x, cpuid_reg[3] 0x%x\n", cpuid_reg[0], cpuid_reg[1], cpuid_reg[2], cpuid_reg[3]);

代替这两组代码，我需要一组，我可以写0到15到'eax'寄存器，以获得完整的CPUID数据了。谢谢帮助。

assembly

来源：https://stackoverflow.com/questions/49684476/add-variable-in-assembly-instruction-asm-inline-c-example

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按热度按时间

vmdwslir1#

您可以读取类似this和this的内容

static inline void cpuid(int code, uint32_t *a, uint32_t *d) {
  asm volatile("cpuid":"=a"(*a),"=d"(*d):"a"(code):"ecx","ebx");
}

/** issue a complete request, storing general registers output as a string
 */
static inline int cpuid_string(int code, uint32_t where[4]) {
  asm volatile("cpuid":"=a"(*where),"=b"(*(where+1)),
               "=c"(*(where+2)),"=d"(*(where+3)):"a"(code));
  return (int)where[0];
}

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assembly 在汇编指令中添加变量(asm inline C示例)

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