Convert ffs() != 0 callers to ctz32()

There are a number of ffs(3) callers that do roughly:

  bit = ffs(val);
  if (bit) {
      do_something(bit - 1);
  }

This pattern can be converted to ctz32() like this:

  zeroes = ctz32(val);
  if (zeroes != 32) {
      do_something(zeroes);
  }

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-6-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/hw/arm/omap1.c b/hw/arm/omap1.c
index 91ffb589e5..de2b289257 100644
--- a/hw/arm/omap1.c
+++ b/hw/arm/omap1.c
@@ -2004,8 +2004,7 @@ 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);
@@ -2017,8 +2016,7 @@ static void omap_mpuio_write(void *opaque, hwaddr addr,
         s->dir = value;
 
         value = s->outputs & ~s->dir;
-        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);