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softfloat: Add float/double to 16 bit integer conversion functions 

The ARM architecture needs float/double to 16 bit integer conversions.
(The 32 bit versions aren't sufficient because of the requirement
to saturate at 16 bit MAXINT/MININT and to get the exception bits right.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Nathan Froyd <froydnj@codesourcery.com>
This commit is contained in:
Peter Maydell 2010-12-07 15:37:34 +00:00
parent 26a5e69aaf
commit cbcef455a2
2 changed files with 140 additions and 0 deletions
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136
fpu/softfloat.c
View File

@ -1353,6 +1353,55 @@ int32 float32_to_int32_round_to_zero( float32 a STATUS_PARAM )
}
/*----------------------------------------------------------------------------
| Returns the result of converting the single-precision floating-point value
| `a' to the 16-bit two's complement integer format. The conversion is
| performed according to the IEC/IEEE Standard for Binary Floating-Point
| Arithmetic, except that the conversion is always rounded toward zero.
| If `a' is a NaN, the largest positive integer is returned. Otherwise, if
| the conversion overflows, the largest integer with the same sign as `a' is
| returned.
*----------------------------------------------------------------------------*/
int16 float32_to_int16_round_to_zero( float32 a STATUS_PARAM )
{
flag aSign;
int16 aExp, shiftCount;
bits32 aSig;
int32 z;
aSig = extractFloat32Frac( a );
aExp = extractFloat32Exp( a );
aSign = extractFloat32Sign( a );
shiftCount = aExp - 0x8E;
if ( 0 <= shiftCount ) {
if ( float32_val(a) != 0xC7000000 ) {
float_raise( float_flag_invalid STATUS_VAR);
if ( ! aSign || ( ( aExp == 0xFF ) && aSig ) ) {
return 0x7FFF;
}
}
return (sbits32) 0xffff8000;
}
else if ( aExp <= 0x7E ) {
if ( aExp | aSig ) {
STATUS(float_exception_flags) |= float_flag_inexact;
}
return 0;
}
shiftCount -= 0x10;
aSig = ( aSig | 0x00800000 )<<8;
z = aSig>>( - shiftCount );
if ( (bits32) ( aSig<<( shiftCount & 31 ) ) ) {
STATUS(float_exception_flags) |= float_flag_inexact;
}
if ( aSign ) {
z = - z;
}
return z;
}
/*----------------------------------------------------------------------------
| Returns the result of converting the single-precision floating-point value
| `a' to the 64-bit two's complement integer format. The conversion is
@ -2410,6 +2459,57 @@ int32 float64_to_int32_round_to_zero( float64 a STATUS_PARAM )
}
/*----------------------------------------------------------------------------
| Returns the result of converting the double-precision floating-point value
| `a' to the 16-bit two's complement integer format. The conversion is
| performed according to the IEC/IEEE Standard for Binary Floating-Point
| Arithmetic, except that the conversion is always rounded toward zero.
| If `a' is a NaN, the largest positive integer is returned. Otherwise, if
| the conversion overflows, the largest integer with the same sign as `a' is
| returned.
*----------------------------------------------------------------------------*/
int16 float64_to_int16_round_to_zero( float64 a STATUS_PARAM )
{
flag aSign;
int16 aExp, shiftCount;
bits64 aSig, savedASig;
int32 z;
aSig = extractFloat64Frac( a );
aExp = extractFloat64Exp( a );
aSign = extractFloat64Sign( a );
if ( 0x40E < aExp ) {
if ( ( aExp == 0x7FF ) && aSig ) {
aSign = 0;
}
goto invalid;
}
else if ( aExp < 0x3FF ) {
if ( aExp || aSig ) {
STATUS(float_exception_flags) |= float_flag_inexact;
}
return 0;
}
aSig |= LIT64( 0x0010000000000000 );
shiftCount = 0x433 - aExp;
savedASig = aSig;
aSig >>= shiftCount;
z = aSig;
if ( aSign ) {
z = - z;
}
if ( ( (int16_t)z < 0 ) ^ aSign ) {
invalid:
float_raise( float_flag_invalid STATUS_VAR);
return aSign ? (sbits32) 0xffff8000 : 0x7FFF;
}
if ( ( aSig<<shiftCount ) != savedASig ) {
STATUS(float_exception_flags) |= float_flag_inexact;
}
return z;
}
/*----------------------------------------------------------------------------
| Returns the result of converting the double-precision floating-point value
| `a' to the 64-bit two's complement integer format. The conversion is
@ -5632,6 +5732,24 @@ unsigned int float32_to_uint32_round_to_zero( float32 a STATUS_PARAM )
return res;
}
unsigned int float32_to_uint16_round_to_zero( float32 a STATUS_PARAM )
{
int64_t v;
unsigned int res;
v = float32_to_int64_round_to_zero(a STATUS_VAR);
if (v < 0) {
res = 0;
float_raise( float_flag_invalid STATUS_VAR);
} else if (v > 0xffff) {
res = 0xffff;
float_raise( float_flag_invalid STATUS_VAR);
} else {
res = v;
}
return res;
}
unsigned int float64_to_uint32( float64 a STATUS_PARAM )
{
int64_t v;
@ -5668,6 +5786,24 @@ unsigned int float64_to_uint32_round_to_zero( float64 a STATUS_PARAM )
return res;
}
unsigned int float64_to_uint16_round_to_zero( float64 a STATUS_PARAM )
{
int64_t v;
unsigned int res;
v = float64_to_int64_round_to_zero(a STATUS_VAR);
if (v < 0) {
res = 0;
float_raise( float_flag_invalid STATUS_VAR);
} else if (v > 0xffff) {
res = 0xffff;
float_raise( float_flag_invalid STATUS_VAR);
} else {
res = v;
}
return res;
}
/* FIXME: This looks broken. */
uint64_t float64_to_uint64 (float64 a STATUS_PARAM)
{

4
fpu/softfloat.h
View File

@ -251,6 +251,8 @@ float32 float16_to_float32( bits16, flag STATUS_PARAM );
/*----------------------------------------------------------------------------
| Software IEC/IEEE single-precision conversion routines.
*----------------------------------------------------------------------------*/
int float32_to_int16_round_to_zero( float32 STATUS_PARAM );
unsigned int float32_to_uint16_round_to_zero( float32 STATUS_PARAM );
int float32_to_int32( float32 STATUS_PARAM );
int float32_to_int32_round_to_zero( float32 STATUS_PARAM );
unsigned int float32_to_uint32( float32 STATUS_PARAM );
@ -327,6 +329,8 @@ INLINE int float32_is_any_nan(float32 a)
/*----------------------------------------------------------------------------
| Software IEC/IEEE double-precision conversion routines.
*----------------------------------------------------------------------------*/
int float64_to_int16_round_to_zero( float64 STATUS_PARAM );
unsigned int float64_to_uint16_round_to_zero( float64 STATUS_PARAM );
int float64_to_int32( float64 STATUS_PARAM );
int float64_to_int32_round_to_zero( float64 STATUS_PARAM );
unsigned int float64_to_uint32( float64 STATUS_PARAM );