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Subject: Re: [Qemu-devel] [PATCH 3/7] Convert ffs() != 0 callers to ctz32()
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To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Markus Armbruster <armbru@redhat.com>

On 03/17/2015 04:56 AM, Stefan Hajnoczi wrote:
> @@ -1989,8 +1989,7 @@ static void omap_mpuio_write(void *opaque, hwaddr addr,
>      case 0x04:	/* OUTPUT_REG */
>          diff = (s->outputs ^ value) & ~s->dir;
>          s->outputs = value;
> -        while ((ln = ffs(diff))) {
> -            ln --;
> +        while ((ln = ctz32(diff)) != 32) {
>              if (s->handler[ln])
>                  qemu_set_irq(s->handler[ln], (value >> ln) & 1);
>              diff &= ~(1 << ln);

Surely

	while (diff != 0) {
	    ln = ctz32(diff);
	    ...
	}

would be a better conversion.


r~