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, 4 insertions, 4 deletions

diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index e336bdb4a9..6e2ad8221b 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -814,12 +814,12 @@ static uint32_t find_free_port_id(VirtIOSerial *vser)
 
     max_nr_ports = vser->serial.max_virtserial_ports;
     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
-        uint32_t map, bit;
+        uint32_t map, zeroes;
 
         map = vser->ports_map[i];
-        bit = ffs(~map);
-        if (bit) {
-            return (bit - 1) + i * 32;
+        zeroes = ctz32(~map);
+        if (zeroes != 32) {
+            return zeroes + i * 32;
         }
     }
     return VIRTIO_CONSOLE_BAD_ID;