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, 5 insertions, 8 deletions

diff --git a/hw/gpio/omap_gpio.c b/hw/gpio/omap_gpio.c
index 9a43486890..d92f8cfbae 100644
--- a/hw/gpio/omap_gpio.c
+++ b/hw/gpio/omap_gpio.c
@@ -125,8 +125,7 @@ static void omap_gpio_write(void *opaque, hwaddr addr,
     case 0x04:	/* DATA_OUTPUT */
         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);
@@ -138,8 +137,7 @@ static void omap_gpio_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);
@@ -253,8 +251,7 @@ static inline void omap2_gpio_module_out_update(struct omap2_gpio_s *s,
 
     s->outputs ^= diff;
     diff &= ~s->dir;
-    while ((ln = ffs(diff))) {
-        ln --;
+    while ((ln = ctz32(diff)) != 32) {
         qemu_set_irq(s->handler[ln], (s->outputs >> ln) & 1);
         diff &= ~(1 << ln);
     }
@@ -442,8 +439,8 @@ static void omap2_gpio_module_write(void *opaque, hwaddr addr,
         s->dir = value;
 
         value = s->outputs & ~s->dir;
-        while ((ln = ffs(diff))) {
-            diff &= ~(1 <<-- ln);
+        while ((ln = ctz32(diff)) != 32) {
+            diff &= ~(1 << ln);
             qemu_set_irq(s->handler[ln], (value >> ln) & 1);
         }