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softfloat: Add float*_min() and float*_max() functions

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Add min and max operations to softfloat. This allows us to implement
propagation of NaNs and handling of negative zero correctly (unlike
the approach of having target helper routines return one of the operands
based on the result of a comparison op).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Peter Maydell 2011-03-11 08:12:25 +00:00 • committed by Aurelien Jarno
parent 79c18be7df
commit 274f1b041e
2 changed files with 53 additions and 0 deletions
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49
fpu/softfloat.c
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@ -6057,6 +6057,55 @@ int float128_compare_quiet( float128 a, float128 b STATUS_PARAM )
return float128_compare_internal(a, b, 1 STATUS_VAR);
}
/* min() and max() functions. These can't be implemented as
* 'compare and pick one input' because that would mishandle
* NaNs and +0 vs -0.
*/
#define MINMAX(s, nan_exp) \
INLINE float ## s float ## s ## _minmax(float ## s a, float ## s b, \
int ismin STATUS_PARAM ) \
{ \
flag aSign, bSign; \
uint ## s ## _t av, bv; \
a = float ## s ## _squash_input_denormal(a STATUS_VAR); \
b = float ## s ## _squash_input_denormal(b STATUS_VAR); \
if (float ## s ## _is_any_nan(a) || \
float ## s ## _is_any_nan(b)) { \
return propagateFloat ## s ## NaN(a, b STATUS_VAR); \
} \
aSign = extractFloat ## s ## Sign(a); \
bSign = extractFloat ## s ## Sign(b); \
av = float ## s ## _val(a); \
bv = float ## s ## _val(b); \
if (aSign != bSign) { \
if (ismin) { \
return aSign ? a : b; \
} else { \
return aSign ? b : a; \
} \
} else { \
if (ismin) { \
return (aSign ^ (av < bv)) ? a : b; \
} else { \
return (aSign ^ (av < bv)) ? b : a; \
} \
} \
} \
\
float ## s float ## s ## _min(float ## s a, float ## s b STATUS_PARAM) \
{ \
return float ## s ## _minmax(a, b, 1 STATUS_VAR); \
} \
\
float ## s float ## s ## _max(float ## s a, float ## s b STATUS_PARAM) \
{ \
return float ## s ## _minmax(a, b, 0 STATUS_VAR); \
}
MINMAX(32, 0xff)
MINMAX(64, 0x7ff)
/* Multiply A by 2 raised to the power N. */
float32 float32_scalbn( float32 a, int n STATUS_PARAM )
{