[Qemu-devel] [PATCH 1/9] softfloat: Introduce float32_to_uint64_round_to_zero

[Tom Musta <tommusta@gmail.com>]

This change adds the float32_to_uint64_round_to_zero function to the softfloat
library.  This function fills out the complement of float32 to INT round-to-zero
conversion rountines, where INT is {int32_t, uint32_t, int64_t, uint64_t}.

This contribution can be licensed under either the softfloat-2a or -2b
license.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Tested-by: Tom Musta <tommusta@gmail.com>
---
 fpu/softfloat.c         |   54 +++++++++++++++++++++++++++++++++++++++++++++++
 include/fpu/softfloat.h |    1 +
 2 files changed, 55 insertions(+), 0 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 5f02c16..d6df78a 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -1628,6 +1628,60 @@ uint64 float32_to_uint64(float32 a STATUS_PARAM)
 
 /*----------------------------------------------------------------------------
 | Returns the result of converting the single-precision floating-point value
+| `a' to the 64-bit unsigned integer format.  The conversion is
+| performed according to the IEC/IEEE Standard for Binary Floating-Point
+| Arithmetic, except that the conversion is always rounded toward zero.  If
+| `a' is a NaN, the largest unsigned integer is returned.  Otherwise, if the
+| conversion overflows, the largest unsigned integer is returned.  If the
+| 'a' is negative, the result is rounded and zero is returned; values that do
+| not round to zero will raise the inexact flag.
+*----------------------------------------------------------------------------*/
+
+uint64 float32_to_uint64_round_to_zero(float32 a STATUS_PARAM)
+{
+    flag aSign;
+    int_fast16_t aExp, shiftCount;
+    uint32_t aSig;
+    uint64_t aSig64;
+    uint64_t z;
+    a = float32_squash_input_denormal(a STATUS_VAR);
+
+    aSig = extractFloat32Frac(a);
+    aExp = extractFloat32Exp(a);
+    aSign = extractFloat32Sign(a);
+    if ((aSign) && (aExp > 126)) {
+        float_raise(float_flag_invalid STATUS_VAR);
+        if (float32_is_any_nan(a)) {
+            return LIT64(0xFFFFFFFFFFFFFFFF);
+        } else {
+            return 0;
+        }
+    }
+    shiftCount = 0xBE - aExp;
+    if (aExp) {
+        aSig |= 0x00800000;
+    }
+    if (shiftCount < 0) {
+        float_raise(float_flag_invalid STATUS_VAR);
+        return LIT64(0xFFFFFFFFFFFFFFFF);
+    } else if (aExp <= 0x7E) {
+        if (aExp | aSig) {
+            STATUS(float_exception_flags) |= float_flag_inexact;
+        }
+        return 0;
+    }
+
+    aSig64 = aSig;
+    aSig64 <<= 40;
+    z = aSig64 >> shiftCount;
+    if (shiftCount && ((uint64_t)(aSig64 << (-shiftCount & 63)))) {
+        STATUS(float_exception_flags) |= float_flag_inexact;
+    }
+    return z;
+}
+
+/*----------------------------------------------------------------------------
+| Returns the result of converting the single-precision floating-point value
 | `a' to the 64-bit two's complement integer format.  The conversion is
 | performed according to the IEC/IEEE Standard for Binary Floating-Point
 | Arithmetic, except that the conversion is always rounded toward zero.  If
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index db878c1..4b3090c 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -342,6 +342,7 @@ uint32 float32_to_uint32( float32 STATUS_PARAM );
 uint32 float32_to_uint32_round_to_zero( float32 STATUS_PARAM );
 int64 float32_to_int64( float32 STATUS_PARAM );
 uint64 float32_to_uint64(float32 STATUS_PARAM);
+uint64 float32_to_uint64_round_to_zero(float32 STATUS_PARAM);
 int64 float32_to_int64_round_to_zero( float32 STATUS_PARAM );
 float64 float32_to_float64( float32 STATUS_PARAM );
 floatx80 float32_to_floatx80( float32 STATUS_PARAM );
-- 
1.7.1