softfloat: improve description of comparison functions

Make clear for all comparison functions which ones trigger an exception
for all NaNs, and which one only for sNaNs.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 48 insertions, 37 deletions

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index efd718b..6ce0b61 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -2338,9 +2338,9 @@ int float32_eq( float32 a, float32 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the single-precision floating-point value `a' is less than
-| or equal to the corresponding value `b', and 0 otherwise.  The comparison
-| is performed according to the IEC/IEEE Standard for Binary Floating-Point
-| Arithmetic.
+| or equal to the corresponding value `b', and 0 otherwise.  The invalid
+| exception is raised if either operand is a NaN.  The comparison is performed
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float32_le( float32 a, float32 b STATUS_PARAM )
@@ -2367,8 +2367,9 @@ int float32_le( float32 a, float32 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the single-precision floating-point value `a' is less than
-| the corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| the corresponding value `b', and 0 otherwise.  The invalid exception is
+| raised if either operand is a NaN.  The comparison is performed according
+| to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float32_lt( float32 a, float32 b STATUS_PARAM )
@@ -2395,8 +2396,9 @@ int float32_lt( float32 a, float32 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the single-precision floating-point values `a' and `b' cannot
-| be compared, and 0 otherwise.  The comparison is performed according to the
-| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| be compared, and 0 otherwise.  The invalid exception is raised if either
+| operand is a NaN.  The comparison is performed according to the IEC/IEEE
+| Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float32_unordered( float32 a, float32 b STATUS_PARAM )
@@ -2415,8 +2417,9 @@ int float32_unordered( float32 a, float32 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the single-precision floating-point value `a' is equal to
-| the corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| the corresponding value `b', and 0 otherwise.  Quiet NaNs do not cause an
+| exception.  The comparison is performed according to the IEC/IEEE Standard
+| for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float32_eq_quiet( float32 a, float32 b STATUS_PARAM )
@@ -3602,9 +3605,9 @@ int float64_eq( float64 a, float64 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the double-precision floating-point value `a' is less than or
-| equal to the corresponding value `b', and 0 otherwise.  The comparison is
-| performed according to the IEC/IEEE Standard for Binary Floating-Point
-| Arithmetic.
+| equal to the corresponding value `b', and 0 otherwise.  The invalid
+| exception is raised if either operand is a NaN.  The comparison is performed
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float64_le( float64 a, float64 b STATUS_PARAM )
@@ -3631,8 +3634,9 @@ int float64_le( float64 a, float64 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the double-precision floating-point value `a' is less than
-| the corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| the corresponding value `b', and 0 otherwise.  The invalid exception is
+| raised if either operand is a NaN.  The comparison is performed according
+| to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float64_lt( float64 a, float64 b STATUS_PARAM )
@@ -3659,8 +3663,9 @@ int float64_lt( float64 a, float64 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the double-precision floating-point values `a' and `b' cannot
-| be compared, and 0 otherwise.  The comparison is performed according to the
-| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| be compared, and 0 otherwise.  The invalid exception is raised if either
+| operand is a NaN.  The comparison is performed according to the IEC/IEEE
+| Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float64_unordered( float64 a, float64 b STATUS_PARAM )
@@ -3679,8 +3684,9 @@ int float64_unordered( float64 a, float64 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the double-precision floating-point value `a' is equal to the
-| corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| corresponding value `b', and 0 otherwise.  Quiet NaNs do not cause an
+| exception.The comparison is performed according to the IEC/IEEE Standard
+| for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float64_eq_quiet( float64 a, float64 b STATUS_PARAM )
@@ -4614,8 +4620,9 @@ int floatx80_eq( floatx80 a, floatx80 b STATUS_PARAM )
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point value `a' is
 | less than or equal to the corresponding value `b', and 0 otherwise.  The
-| comparison is performed according to the IEC/IEEE Standard for Binary
-| Floating-Point Arithmetic.
+| invalid exception is raised if either operand is a NaN.  The comparison is
+| performed according to the IEC/IEEE Standard for Binary Floating-Point
+| Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int floatx80_le( floatx80 a, floatx80 b STATUS_PARAM )
@@ -4646,9 +4653,9 @@ int floatx80_le( floatx80 a, floatx80 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point value `a' is
-| less than the corresponding value `b', and 0 otherwise.  The comparison
-| is performed according to the IEC/IEEE Standard for Binary Floating-Point
-| Arithmetic.
+| less than the corresponding value `b', and 0 otherwise.  The invalid
+| exception is raised if either operand is a NaN.  The comparison is performed
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int floatx80_lt( floatx80 a, floatx80 b STATUS_PARAM )
@@ -4679,8 +4686,9 @@ int floatx80_lt( floatx80 a, floatx80 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point values `a' and `b'
-| cannot be compared, and 0 otherwise.  The comparison is performed according
-| to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| cannot be compared, and 0 otherwise.  The invalid exception is raised if
+| either operand is a NaN.   The comparison is performed according to the
+| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 int floatx80_unordered( floatx80 a, floatx80 b STATUS_PARAM )
 {
@@ -4697,9 +4705,9 @@ int floatx80_unordered( floatx80 a, floatx80 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the extended double-precision floating-point value `a' is
-| equal to the corresponding value `b', and 0 otherwise.  The comparison is
-| performed according to the IEC/IEEE Standard for Binary Floating-Point
-| Arithmetic.
+| equal to the corresponding value `b', and 0 otherwise.  Quiet NaNs do not
+| cause an exception.  The comparison is performed according to the IEC/IEEE
+| Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int floatx80_eq_quiet( floatx80 a, floatx80 b STATUS_PARAM )
@@ -5776,9 +5784,9 @@ int float128_eq( float128 a, float128 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the quadruple-precision floating-point value `a' is less than
-| or equal to the corresponding value `b', and 0 otherwise.  The comparison
-| is performed according to the IEC/IEEE Standard for Binary Floating-Point
-| Arithmetic.
+| or equal to the corresponding value `b', and 0 otherwise.  The invalid
+| exception is raised if either operand is a NaN.  The comparison is performed
+| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float128_le( float128 a, float128 b STATUS_PARAM )
@@ -5809,8 +5817,9 @@ int float128_le( float128 a, float128 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the quadruple-precision floating-point value `a' is less than
-| the corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| the corresponding value `b', and 0 otherwise.  The invalid exception is
+| raised if either operand is a NaN.  The comparison is performed according
+| to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float128_lt( float128 a, float128 b STATUS_PARAM )
@@ -5841,8 +5850,9 @@ int float128_lt( float128 a, float128 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the quadruple-precision floating-point values `a' and `b' cannot
-| be compared, and 0 otherwise.  The comparison is performed according to the
-| IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| be compared, and 0 otherwise.  The invalid exception is raised if either
+| operand is a NaN. The comparison is performed according to the IEC/IEEE
+| Standard for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float128_unordered( float128 a, float128 b STATUS_PARAM )
@@ -5860,8 +5870,9 @@ int float128_unordered( float128 a, float128 b STATUS_PARAM )
 
 /*----------------------------------------------------------------------------
 | Returns 1 if the quadruple-precision floating-point value `a' is equal to
-| the corresponding value `b', and 0 otherwise.  The comparison is performed
-| according to the IEC/IEEE Standard for Binary Floating-Point Arithmetic.
+| the corresponding value `b', and 0 otherwise.  Quiet NaNs do not cause an
+| exception.  The comparison is performed according to the IEC/IEEE Standard
+| for Binary Floating-Point Arithmetic.
 *----------------------------------------------------------------------------*/
 
 int float128_eq_quiet( float128 a, float128 b STATUS_PARAM )