softfloat: Move propagateFloatx80NaN to softfloat.c

This function is part of the public interface and
is not "specialized" to any target in any way.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20241203203949.483774-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 027a8e576d..6ba1cfd32a 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -4921,6 +4921,58 @@ void normalizeFloatx80Subnormal(uint64_t aSig, int32_t *zExpPtr,
 }
 
 /*----------------------------------------------------------------------------
+| Takes two extended double-precision floating-point values `a' and `b', one
+| of which is a NaN, and returns the appropriate NaN result.  If either `a' or
+| `b' is a signaling NaN, the invalid exception is raised.
+*----------------------------------------------------------------------------*/
+
+floatx80 propagateFloatx80NaN(floatx80 a, floatx80 b, float_status *status)
+{
+    bool aIsLargerSignificand;
+    FloatClass a_cls, b_cls;
+
+    /* This is not complete, but is good enough for pickNaN.  */
+    a_cls = (!floatx80_is_any_nan(a)
+             ? float_class_normal
+             : floatx80_is_signaling_nan(a, status)
+             ? float_class_snan
+             : float_class_qnan);
+    b_cls = (!floatx80_is_any_nan(b)
+             ? float_class_normal
+             : floatx80_is_signaling_nan(b, status)
+             ? float_class_snan
+             : float_class_qnan);
+
+    if (is_snan(a_cls) || is_snan(b_cls)) {
+        float_raise(float_flag_invalid, status);
+    }
+
+    if (status->default_nan_mode) {
+        return floatx80_default_nan(status);
+    }
+
+    if (a.low < b.low) {
+        aIsLargerSignificand = 0;
+    } else if (b.low < a.low) {
+        aIsLargerSignificand = 1;
+    } else {
+        aIsLargerSignificand = (a.high < b.high) ? 1 : 0;
+    }
+
+    if (pickNaN(a_cls, b_cls, aIsLargerSignificand, status)) {
+        if (is_snan(b_cls)) {
+            return floatx80_silence_nan(b, status);
+        }
+        return b;
+    } else {
+        if (is_snan(a_cls)) {
+            return floatx80_silence_nan(a, status);
+        }
+        return a;
+    }
+}
+
+/*----------------------------------------------------------------------------
 | Takes an abstract floating-point value having sign `zSign', exponent `zExp',
 | and extended significand formed by the concatenation of `zSig0' and `zSig1',
 | and returns the proper extended double-precision floating-point value