[Qemu-devel] [PATCH v3 7/9] omap_intc: convert ffs(3) to ctz32() in omap_inth_sir_update()

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Paolo Bonzini <pbonzini@redhat.com>

The loop previously terminated on ffs(0) == 0, now it terminates on
ctz32(0) + 1 == 33.

Other than this change, ffs() is simply replaced with ctz32() + 1.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/intc/omap_intc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/hw/intc/omap_intc.c b/hw/intc/omap_intc.c
index ad3931c..e9b38a3 100644
--- a/hw/intc/omap_intc.c
+++ b/hw/intc/omap_intc.c
@@ -60,7 +60,7 @@ struct omap_intr_handler_s {
 
 static void omap_inth_sir_update(struct omap_intr_handler_s *s, int is_fiq)
 {
-    int i, j, sir_intr, p_intr, p, f;
+    int i, j, sir_intr, p_intr, p;
     uint32_t level;
     sir_intr = 0;
     p_intr = 255;
@@ -72,14 +72,15 @@ static void omap_inth_sir_update(struct omap_intr_handler_s *s, int is_fiq)
     for (j = 0; j < s->nbanks; ++j) {
         level = s->bank[j].irqs & ~s->bank[j].mask &
                 (is_fiq ? s->bank[j].fiq : ~s->bank[j].fiq);
-        for (f = ffs(level), i = f - 1, level >>= f - 1; f; i += f,
-                        level >>= f) {
+
+        while (level != 0) {
+            i = ctz32(level);
             p = s->bank[j].priority[i];
             if (p <= p_intr) {
                 p_intr = p;
                 sir_intr = 32 * j + i;
             }
-            f = ffs(level >> 1);
+            level &= level - 1;
         }
     }
     s->sir_intr[is_fiq] = sir_intr;
-- 
2.1.0