softfloat: Add minNum() and maxNum() functions to softfloat.

Add floatnn_minnum() and floatnn_maxnum() functions which are equivalent
to the minNum() and maxNum() functions from IEEE 754-2008. They are
similar to min() and max() but differ in the handling of QNaN arguments.

Signed-off-by: Will Newton <will.newton@linaro.org>
Message-id: 1386158099-9239-5-git-send-email-will.newton@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 97bf627..dbda61b 100644 (file)
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -6705,10 +6705,17 @@ int float128_compare_quiet( float128 a, float128 b STATUS_PARAM )
 /* min() and max() functions. These can't be implemented as
  * 'compare and pick one input' because that would mishandle
  * NaNs and +0 vs -0.
+ *
+ * minnum() and maxnum() functions. These are similar to the min()
+ * and max() functions but if one of the arguments is a QNaN and
+ * the other is numerical then the numerical argument is returned.
+ * minnum() and maxnum correspond to the IEEE 754-2008 minNum()
+ * and maxNum() operations. min() and max() are the typical min/max
+ * semantics provided by many CPUs which predate that specification.
  */
 #define MINMAX(s)                                                       \
 INLINE float ## s float ## s ## _minmax(float ## s a, float ## s b,     \
-                                        int ismin STATUS_PARAM )        \
+                                        int ismin, int isieee STATUS_PARAM) \
 {                                                                       \
     flag aSign, bSign;                                                  \
     uint ## s ## _t av, bv;                                             \
@@ -6716,6 +6723,15 @@ INLINE float ## s float ## s ## _minmax(float ## s a, float ## s b,     \
     b = float ## s ## _squash_input_denormal(b STATUS_VAR);             \
     if (float ## s ## _is_any_nan(a) ||                                 \
         float ## s ## _is_any_nan(b)) {                                 \
+        if (isieee) {                                                   \
+            if (float ## s ## _is_quiet_nan(a) &&                       \
+                !float ## s ##_is_any_nan(b)) {                         \
+                return b;                                               \
+            } else if (float ## s ## _is_quiet_nan(b) &&                \
+                       !float ## s ## _is_any_nan(a)) {                 \
+                return a;                                               \
+            }                                                           \
+        }                                                               \
         return propagateFloat ## s ## NaN(a, b STATUS_VAR);             \
     }                                                                   \
     aSign = extractFloat ## s ## Sign(a);                               \
@@ -6739,12 +6755,22 @@ INLINE float ## s float ## s ## _minmax(float ## s a, float ## s b,     \
                                                                         \
 float ## s float ## s ## _min(float ## s a, float ## s b STATUS_PARAM)  \
 {                                                                       \
-    return float ## s ## _minmax(a, b, 1 STATUS_VAR);                   \
+    return float ## s ## _minmax(a, b, 1, 0 STATUS_VAR);                \
 }                                                                       \
                                                                         \
 float ## s float ## s ## _max(float ## s a, float ## s b STATUS_PARAM)  \
 {                                                                       \
-    return float ## s ## _minmax(a, b, 0 STATUS_VAR);                   \
+    return float ## s ## _minmax(a, b, 0, 0 STATUS_VAR);                \
+}                                                                       \
+                                                                        \
+float ## s float ## s ## _minnum(float ## s a, float ## s b STATUS_PARAM) \
+{                                                                       \
+    return float ## s ## _minmax(a, b, 1, 1 STATUS_VAR);                \
+}                                                                       \
+                                                                        \
+float ## s float ## s ## _maxnum(float ## s a, float ## s b STATUS_PARAM) \
+{                                                                       \
+    return float ## s ## _minmax(a, b, 0, 1 STATUS_VAR);                \
 }
 
 MINMAX(32)

diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index f3927e2..2365274 100644 (file)
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -302,6 +302,8 @@ int float32_compare( float32, float32 STATUS_PARAM );
 int float32_compare_quiet( float32, float32 STATUS_PARAM );
 float32 float32_min(float32, float32 STATUS_PARAM);
 float32 float32_max(float32, float32 STATUS_PARAM);
+float32 float32_minnum(float32, float32 STATUS_PARAM);
+float32 float32_maxnum(float32, float32 STATUS_PARAM);
 int float32_is_quiet_nan( float32 );
 int float32_is_signaling_nan( float32 );
 float32 float32_maybe_silence_nan( float32 );
@@ -408,6 +410,8 @@ int float64_compare( float64, float64 STATUS_PARAM );
 int float64_compare_quiet( float64, float64 STATUS_PARAM );
 float64 float64_min(float64, float64 STATUS_PARAM);
 float64 float64_max(float64, float64 STATUS_PARAM);
+float64 float64_minnum(float64, float64 STATUS_PARAM);
+float64 float64_maxnum(float64, float64 STATUS_PARAM);
 int float64_is_quiet_nan( float64 a );
 int float64_is_signaling_nan( float64 );
 float64 float64_maybe_silence_nan( float64 );