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[Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH 2/4] target-arm: Fix implementation of VRSQRTS |
Date: |
Fri, 7 Jan 2011 09:26:25 +0000 |
The implementation of the ARM VRSQRTS instruction (which calculates
(3 - op1 * op2) / 2) was missing the division operation. It also
did not handle the special cases of (0,inf) and (inf,0).
Signed-off-by: Peter Maydell <address@hidden>
---
target-arm/helper.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 705b99f..ac47de0 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2612,8 +2612,16 @@ float32 HELPER(recps_f32)(float32 a, float32 b, CPUState
*env)
float32 HELPER(rsqrts_f32)(float32 a, float32 b, CPUState *env)
{
float_status *s = &env->vfp.fp_status;
+ float32 two = int32_to_float32(2, s);
float32 three = int32_to_float32(3, s);
- return float32_sub(three, float32_mul(a, b, s), s);
+ float32 product;
+ if ((float32_is_infinity(a) && float32_is_zero_or_denormal(b)) ||
+ (float32_is_infinity(b) && float32_is_zero_or_denormal(a))) {
+ product = float32_zero;
+ } else {
+ product = float32_mul(a, b, s);
+ }
+ return float32_div(float32_sub(three, product, s), two, s);
}
/* NEON helpers. */
--
1.6.3.3