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

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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>
This commit is contained in:
Stefan Hajnoczi 2015-03-23 15:29:27 +00:00 • committed by Kevin Wolf
parent 786a4ea82e
commit bd2a88840e
6 changed files with 26 additions and 27 deletions
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8
hw/char/virtio-serial-bus.c
View file

@ -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;