softfloat: Add float16 type and float16 NaN handling functions
Add a float16 type to softfloat, rather than using bits16 directly.
Also add the missing functions float16_is_quiet_nan(),
float16_is_signaling_nan() and float16_maybe_silence_nan(),
which are needed for the float16 conversion routines.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
index eb644b2..495f6f3 100644
--- a/fpu/softfloat-specialize.h
+++ b/fpu/softfloat-specialize.h
@@ -57,6 +57,69 @@
} commonNaNT;
/*----------------------------------------------------------------------------
+| The pattern for a default generated half-precision NaN.
+*----------------------------------------------------------------------------*/
+#if defined(TARGET_ARM)
+#define float16_default_nan make_float16(0x7E00)
+#elif SNAN_BIT_IS_ONE
+#define float16_default_nan make_float16(0x7DFF)
+#else
+#define float16_default_nan make_float16(0xFE00)
+#endif
+
+/*----------------------------------------------------------------------------
+| Returns 1 if the half-precision floating-point value `a' is a quiet
+| NaN; otherwise returns 0.
+*----------------------------------------------------------------------------*/
+
+int float16_is_quiet_nan(float16 a_)
+{
+ uint16_t a = float16_val(a_);
+#if SNAN_BIT_IS_ONE
+ return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);
+#else
+ return ((a & ~0x8000) >= 0x7c80);
+#endif
+}
+
+/*----------------------------------------------------------------------------
+| Returns 1 if the half-precision floating-point value `a' is a signaling
+| NaN; otherwise returns 0.
+*----------------------------------------------------------------------------*/
+
+int float16_is_signaling_nan(float16 a_)
+{
+ uint16_t a = float16_val(a_);
+#if SNAN_BIT_IS_ONE
+ return ((a & ~0x8000) >= 0x7c80);
+#else
+ return (((a >> 9) & 0x3F) == 0x3E) && (a & 0x1FF);
+#endif
+}
+
+/*----------------------------------------------------------------------------
+| Returns a quiet NaN if the half-precision floating point value `a' is a
+| signaling NaN; otherwise returns `a'.
+*----------------------------------------------------------------------------*/
+float16 float16_maybe_silence_nan(float16 a_)
+{
+ if (float16_is_signaling_nan(a_)) {
+#if SNAN_BIT_IS_ONE
+# if defined(TARGET_MIPS) || defined(TARGET_SH4)
+ return float16_default_nan;
+# else
+# error Rules for silencing a signaling NaN are target-specific
+# endif
+#else
+ uint16_t a = float16_val(a_);
+ a |= (1 << 9);
+ return make_float16(a);
+#endif
+ }
+ return a_;
+}
+
+/*----------------------------------------------------------------------------
| The pattern for a default generated single-precision NaN.
*----------------------------------------------------------------------------*/
#if defined(TARGET_SPARC)
