[Qemu-devel] [PATCH 11/18] softfloat: Fix float64_to_uint32

[Tom Musta <tommusta@gmail.com>]

The float64_to_uint32 has several flaws:

 - for numbers between 2**32 and 2**64, the inexact exception flag
   may get incorrectly set.  In this case, only the invalid flag
   should be set.

       test pattern: 425F81378DC0CD1F / 0x1.f81378dc0cd1fp+38

 - for numbers between 2**63 and 2**64, incorrect results may
   be produced:

       test pattern: 43EAAF73F1F0B8BD / 0x1.aaf73f1f0b8bdp+63

This patch re-implements float64_to_uint32 to re-use the
float64_to_uint64 routine (instead of float64_to_int64).  For the
saturation case, the inexact bit is explicitly cleared before raising
the invalid flag.

Signed-off-by: Tom Musta <tommusta@gmail.com>
---
 fpu/softfloat.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 1003e59..6a8b6f5 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -6578,15 +6578,13 @@ uint_fast16_t float32_to_uint16_round_to_zero(float32 a STATUS_PARAM)
 
 uint32 float64_to_uint32( float64 a STATUS_PARAM )
 {
-    int64_t v;
+    uint64_t v;
     uint32 res;
 
-    v = float64_to_int64(a STATUS_VAR);
-    if (v < 0) {
-        res = 0;
-        float_raise( float_flag_invalid STATUS_VAR);
-    } else if (v > 0xffffffff) {
+    v = float64_to_uint64(a STATUS_VAR);
+    if (v > 0xffffffff) {
         res = 0xffffffff;
+        STATUS(float_exception_flags) &= ~float_flag_inexact;
         float_raise( float_flag_invalid STATUS_VAR);
     } else {
         res = v;
-- 
1.7.1