mips_lock.c

/*
 *
 *  simple locking test program
 *  (no paralles stuff)
 * 
 *  Compile with: gcc -D__CPU_i386 -O3 on x86 machines and
 *                gcc -mips2 -O2 -D__CPU_mips  on mips machines.
 *  -- andrei
 *
 *  
 */

#include <stdio.h>

typedef volatile int fl_lock_t;



int tsl(fl_lock_t* lock)
{
        long val;
        
#ifdef __CPU_mips
        long tmp=0;
        
        asm volatile(
                ".set noreorder\n\t"
                "1:  ll %1, %2   \n\t"
                "    li %0, 1 \n\t"
                "    sc %0, %2  \n\t"
                "    beqz %0, 1b \n\t"
                "    nop \n\t"
                ".set reorder\n\t"
                : "=&r" (tmp), "=&r" (val), "=m" (*lock) 
                : "0" (tmp), "m" (*lock) 
                : "cc"
        );
#elif defined __CPU_i386
        val=1;
        asm volatile( 
                " xchg %b1, %0" : "=q" (val), "=m" (*lock) : "0" (val) 
        );
#else
#error "cpu type not defined, add -D__CPU_<type> when compiling"
#endif
        
        return val;
}



void release_lock(fl_lock_t* lock)
{
#ifdef __CPU_mips
        int tmp;
        tmp=0;
        asm volatile(
                ".set noreorder \n\t"
                "    sync \n\t"
                "    sw $0, %0 \n\t"
                ".set reorder \n\t"
                : /*no output*/  : "m" (*lock) : "memory"
        );
#elif defined __CPU_i386
        asm volatile(
                " movb $0, (%0)" : /*no output*/ : "r"(lock): "memory"
        ); 
#else
#error "cpu type not defined, add -D__CPU_<type> when compiling"
#endif
}



int main(int argc, char** argv)
{
        fl_lock_t lock;
        int r;
        
        lock=0;
        printf("starting locking basic tests...\n");
        
        r=tsl(&lock);
        printf(" tsl should return 0                 ... %d\n", r);
        printf("     lock should be 1 now            ... %d\n", lock);
        r=tsl(&lock);
        printf(" tsl should return 1                 ... %d\n", r);
        printf("     lock should still be 1 now      ... %d\n", lock);
        release_lock(&lock);
        printf(" release_lock: lock should be 0 now  ... %d\n", lock);
        printf("trying tsl once more...\n");
        r=tsl(&lock);
        printf(" tsl should return 0                 ... %d\n", r);
        printf("     lock should be 1 now            ... %d\n", lock);
        printf("\ndone.\n");
        return 0;
}