dec_if_positive 235 Bytes
cat <<EOF
static inline ${ret}
${atomic}_dec_if_positive(${atomic}_t *v)
{
	${int} dec, c = ${atomic}_read(v);

	do {
		dec = c - 1;
		if (unlikely(dec < 0))
			break;
	} while (!${atomic}_try_cmpxchg(v, &c, dec));

	return dec;
}
EOF