atomic_dec_if_positive.h

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/* PROLOG END TAG zYx                                              */
#ifndef _SPU_ATOMIC_DEC_IF_POSITIVE_H_
#define _SPU_ATOMIC_DEC_IF_POSITIVE_H_

#include <sync_utils.h>
#include <atomic.h>

/**
 * atomic_dec_if_positive - atomically decrement if counter is positive.
 * @v: handle to effective address of counter.
 * 
 * Atomically decrement a counter if its value is positive.
 * The only restriction is that @v must be word aligned.
 *
*
 * Returns the old value of the counter, minus 1.
 */
static __inline int _atomic_dec_if_positive(atomic_ea_t v)
{
    DECL_ATOMIC_VARS();
    s32 status;

    ea64.ull = ALIGN128_EA(v);
    offset = OFFSET128_EA_U32(v);
    do {
        MFC_DMA(buf, ea64, size, tagid, MFC_GETLLAR_CMD);
        spu_readch(MFC_RdAtomicStat);

        ret_val = buf[offset] - 1;
        if (likely(ret_val >= 0)) {
            buf[offset] = ret_val;
            MFC_DMA(buf, ea64, size, tagid, MFC_PUTLLC_CMD);
            status = spu_readch(MFC_RdAtomicStat);
        } else {
            MFC_DMA(buf, ea64, size, tagid, MFC_PUTLLC_CMD);
            spu_readch(MFC_RdAtomicStat);
            status = 0;
            break;
        }
    } while (status != 0);

    return ret_val;
}



#endif /* _SPU_ATOMIC_DEC_IF_POSITIVE_H_ */