Desktop/xinu_mips-1.0.2.tar/xinu_mips-1.0.2/system/newsem.c

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/* Embedded XINU, Copyright (C) 2007.  All rights reserved. */

#include <kernel.h>
#include <semaphore.h>

static semaphore allocsem(void);

semaphore newsem(short count)
{
        irqmask ps;    
        semaphore sem;

        ps = disable();                     /* disable interrupts    */
        sem = allocsem();                   /* request new semaphore */
        if ( sem != SYSERR && count >= 0 )  /* safety check          */
        {
                semtab[sem].count = count;      /* initialize count      */
                restore(ps);                    /* restore interrupts    */
                return sem;                         /* return semaphore id   */
        }

        restore(ps);
        return SYSERR;
}

static semaphore allocsem(void)
{
        int i = 0;
        while(i < NSEM)                     /* loop through semaphore table */
        {                                   /*  to find SFREE semaphore     */
                if( semtab[i].state == SFREE )
                {
                        semtab[i].state = SUSED;
                        return i;
                }
                i++;
        }
        return SYSERR;
}

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