target-ppc: optimize popcntb
Suggested by Andrzej Zaborowski.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5592 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
index ef1035f..b1a88b5 100644
--- a/target-ppc/op_helper.c
+++ b/target-ppc/op_helper.c
@@ -222,25 +222,19 @@
target_ulong helper_popcntb (target_ulong val)
{
- uint32_t ret;
- int i;
-
- ret = 0;
- for (i = 0; i < 32; i += 8)
- ret |= ctpop8((val >> i) & 0xFF) << i;
- return ret;
+ val = (val & 0x55555555) + ((val >> 1) & 0x55555555);
+ val = (val & 0x33333333) + ((val >> 2) & 0x33333333);
+ val = (val & 0x0f0f0f0f) + ((val >> 4) & 0x0f0f0f0f);
+ return val;
}
#if defined(TARGET_PPC64)
target_ulong helper_popcntb_64 (target_ulong val)
{
- uint64_t ret;
- int i;
-
- ret = 0;
- for (i = 0; i < 64; i += 8)
- ret |= ctpop8((val >> i) & 0xFF) << i;
- return ret;
+ val = (val & 0x5555555555555555ULL) + ((val >> 1) & 0x5555555555555555ULL);
+ val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL);
+ val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >> 4) & 0x0f0f0f0f0f0f0f0fULL);
+ return val;
}
#endif
