#include "syscall.h"

/* 无参数的系统调用 */
#define _syscall0(NUMBER) ({				       \
   int retval;					               \
   asm volatile (					       \
   "pushl %[number]; int $0x80; addl $4, %%esp"		       \
   : "=a" (retval)					       \
   : [number] "i" (NUMBER)		  		       \
   : "memory"						       \
   );							       \
   retval;						       \
})

/* 一个参数的系统调用 */
#define _syscall1(NUMBER, ARG0) ({			       \
   int retval;					               \
   asm volatile (					       \
   "pushl %[arg0]; pushl %[number]; int $0x80; addl $8, %%esp" \
   : "=a" (retval)					       \
   : [number] "i" (NUMBER), [arg0] "g" (ARG0)		       \
   : "memory"						       \
   );							       \
   retval;						       \
})

/* 两个参数的系统调用 */
#define _syscall2(NUMBER, ARG0, ARG1) ({		       \
   int retval;						       \
   asm volatile (					       \
   "pushl %[arg1]; pushl %[arg0]; "			       \
   "pushl %[number]; int $0x80; addl $12, %%esp"	       \
      : "=a" (retval)					       \
      : [number] "i" (NUMBER),				       \
	[arg0] "g" (ARG0),				       \
	[arg1] "g" (ARG1)				       \
      : "memory"					       \
   );							       \
   retval;						       \
})

/* 三个参数的系统调用 */
#define _syscall3(NUMBER, ARG0, ARG1, ARG2) ({		       \
   int retval;						       \
   asm volatile (					       \
      "pushl %[arg2]; pushl %[arg1]; pushl %[arg0]; "	       \
      "pushl %[number]; int $0x80; addl $16, %%esp"	       \
      : "=a" (retval)					       \
      : [number] "i" (NUMBER),				       \
	[arg0] "g" (ARG0),				       \
	[arg1] "g" (ARG1),				       \
	[arg2] "g" (ARG2)				       \
      : "memory"					       \
   );							       \
   retval;						       \
})

/* 返回当前任务pid */
uint32_t getpid() {
   return _syscall0(SYS_GETPID);
}