Convert (ffs(val) - 1) to ctz32(val)

This commit was generated mechanically by coccinelle from the following
semantic patch:

@@
expression val;
@@
- (ffs(val) - 1)
+ ctz32(val)

The call sites have been audited to ensure the ffs(0) - 1 == -1 case
never occurs (due to input validation, asserts, etc).  Therefore we
don't need to worry about the fact that ctz32(0) == 32.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-5-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/hw/pci/msi.c b/hw/pci/msi.c
index 916e1a1..2949938 100644
--- a/hw/pci/msi.c
+++ b/hw/pci/msi.c
@@ -72,7 +72,7 @@ static inline uint8_t msi_cap_sizeof(uint16_t flags)
 static inline unsigned int msi_nr_vectors(uint16_t flags)
 {
     return 1U <<
-        ((flags & PCI_MSI_FLAGS_QSIZE) >> (ffs(PCI_MSI_FLAGS_QSIZE) - 1));
+        ((flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE));
 }
 
 static inline uint8_t msi_flags_off(const PCIDevice* dev)
@@ -175,9 +175,9 @@ int msi_init(struct PCIDevice *dev, uint8_t offset,
     assert(nr_vectors > 0);
     assert(nr_vectors <= PCI_MSI_VECTORS_MAX);
     /* the nr of MSI vectors is up to 32 */
-    vectors_order = ffs(nr_vectors) - 1;
+    vectors_order = ctz32(nr_vectors);
 
-    flags = vectors_order << (ffs(PCI_MSI_FLAGS_QMASK) - 1);
+    flags = vectors_order << ctz32(PCI_MSI_FLAGS_QMASK);
     if (msi64bit) {
         flags |= PCI_MSI_FLAGS_64BIT;
     }
@@ -355,12 +355,12 @@ void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
      * just don't crash the host
      */
     log_num_vecs =
-        (flags & PCI_MSI_FLAGS_QSIZE) >> (ffs(PCI_MSI_FLAGS_QSIZE) - 1);
+        (flags & PCI_MSI_FLAGS_QSIZE) >> ctz32(PCI_MSI_FLAGS_QSIZE);
     log_max_vecs =
-        (flags & PCI_MSI_FLAGS_QMASK) >> (ffs(PCI_MSI_FLAGS_QMASK) - 1);
+        (flags & PCI_MSI_FLAGS_QMASK) >> ctz32(PCI_MSI_FLAGS_QMASK);
     if (log_num_vecs > log_max_vecs) {
         flags &= ~PCI_MSI_FLAGS_QSIZE;
-        flags |= log_max_vecs << (ffs(PCI_MSI_FLAGS_QSIZE) - 1);
+        flags |= log_max_vecs << ctz32(PCI_MSI_FLAGS_QSIZE);
         pci_set_word(dev->config + msi_flags_off(dev), flags);
     }