syscalls.c~

// syscalls.c
// calls to kernel services

#include "kernel_constants.h" // SYS_WRITE 4, SYS_GETPID 20, etc.
#include "syscalls.h"


int sys_getpid(void) {
   int pid;

   asm("movl %1, %%eax;     // service #20 (SYS_GETPID)
        int $128;           // interrupt CPU with IDT entry 128
        movl %%ebx, %0"         //####newline
       : "=g"(pid)         // output syntax  
       : "g"(SYS_GETPID)   // input syntax
       : "eax", "ebx"       // used registers
       );

   return pid;
}

void sys_write(int fileno, char *str, int len) {
   asm(
       "movl %0, %%eax;      // send service #4 (SYS_WRITE) via eax
        movl %1, %%ebx;      // send in fileno via ebx (e.g., STDOUT)
        movl %2, %%ecx;      // send in str addr via ecx
        movl %3, %%edx;      // send in str len via edx
        int $128"          // initiate service call, intr 128 (IDT entry 128)
      
       :                    // no output
       : "g"(SYS_WRITE), "g"(fileno), "g"(str), "g"(len)
       : "eax", "ebx", "ecx", "edx"
       );
}

void sys_sleep(int centi_sec) { // 1 centi-second is 1/100 of a second
   asm(
       "movl %0, %%eax;          // service #162 (SYS_SLEEP)
        movl %1, %%ebx;          // send in centi-seconds via ebx
        int $128"
 
        ://NOT SURE IF I NEED TO ADD THIS...NOT IN Prof's CodingHinits.txt

       : "g"(SYS_SLEEP), "g"(centi_sec)
 //      :"g" (centi_sec)    //###newline
       : "eax", "ebx"
       );
}
/*
void sys_semwait(int sem_num){
asm("movl %0, %%eax;7
	movl %1, %%ebx;
	int $128"
	:
	:"g"(SYS_SEMWAIT), "g"(sem_num)
       :"eax", "ebx"
	);
}

void sys_sempost(int sem_num){
asm("movl %0, %%eax;
	movl %1, %%ebx;
	int $128"
	:
	:"g"(SYS_SEMPOST), "g"(sem_num)
        :"eax", "ebx"
	);
}

*/