[RFC,v1,2/2] softfloat: Add float128_to_uint32_round_to_zero()

Commit Message

Bharata B Rao Feb. 7, 2017, 8:04 a.m. UTC

float128_to_uint32_round_to_zero() is needed by xscvqpuwz instruction
of PowerPC ISA 3.0.

Signed-off-by: Bharata B Rao <[e-mail]>
---
 fpu/softfloat.c         | 28 ++++++++++++++++++++++++++++
 include/fpu/softfloat.h |  1 +
 2 files changed, 29 insertions(+)

Comments

Peter Maydell Feb. 7, 2017, 3:57 p.m. UTC | #1

On 7 February 2017 at 08:04, Bharata B Rao <[e-mail]> wrote:
> float128_to_uint32_round_to_zero() is needed by xscvqpuwz instruction
> of PowerPC ISA 3.0.
>
> Signed-off-by: Bharata B Rao <[e-mail]>
> ---
>  fpu/softfloat.c         | 28 ++++++++++++++++++++++++++++
>  include/fpu/softfloat.h |  1 +
>  2 files changed, 29 insertions(+)
>

Reviewed-by: Peter Maydell <[e-mail]>

thanks
-- PMM

Richard Henderson Feb. 7, 2017, 10:10 p.m. UTC | #2

On 02/07/2017 12:04 AM, Bharata B Rao wrote:
> +    int64_t v;
> +    uint32_t res;
> +    int old_exc_flags = get_float_exception_flags(status);
> +
> +    v = float128_to_uint64_round_to_zero(a, status);
> +    if (v > 0xffffffff) {

v should be uint64_t.


r~

Patch

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 4a4b50b..ed76629 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -6169,6 +6169,34 @@  uint64_t float128_to_uint64_round_to_zero(float128 a, float_status *status)
 
 /*----------------------------------------------------------------------------
 | Returns the result of converting the quadruple-precision floating-point
+| value `a' to the 32-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 positive integer is returned.  Otherwise,
+| if the conversion overflows, the largest unsigned integer is returned.
+| If 'a' is negative, the value is rounded and zero is returned; negative
+| values that do not round to zero will raise the inexact exception.
+*----------------------------------------------------------------------------*/
+
+uint32_t float128_to_uint32_round_to_zero(float128 a, float_status *status)
+{
+    int64_t v;
+    uint32_t res;
+    int old_exc_flags = get_float_exception_flags(status);
+
+    v = float128_to_uint64_round_to_zero(a, status);
+    if (v > 0xffffffff) {
+        res = 0xffffffff;
+    } else {
+        return v;
+    }
+    set_float_exception_flags(old_exc_flags, status);
+    float_raise(float_flag_invalid, status);
+    return res;
+}
+
+/*----------------------------------------------------------------------------
+| Returns the result of converting the quadruple-precision floating-point
 | value `a' to the single-precision floating-point format.  The conversion
 | is performed according to the IEC/IEEE Standard for Binary Floating-Point
 | Arithmetic.
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index 4e99253..9eb5a6b 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -714,6 +714,7 @@  int64_t float128_to_int64(float128, float_status *status);
 int64_t float128_to_int64_round_to_zero(float128, float_status *status);
 uint64_t float128_to_uint64(float128, float_status *status);
 uint64_t float128_to_uint64_round_to_zero(float128, float_status *status);
+uint32_t float128_to_uint32_round_to_zero(float128, float_status *status);
 float32 float128_to_float32(float128, float_status *status);
 float64 float128_to_float64(float128, float_status *status);
 floatx80 float128_to_floatx80(float128, float_status *status);