368 lines
12 KiB
Plaintext
368 lines
12 KiB
Plaintext
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/*
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===============================================================================
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This C source fragment is part of the SoftFloat IEC/IEEE Floating-point
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Arithmetic Package, Release 2.
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Written by John R. Hauser. This work was made possible in part by the
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International Computer Science Institute, located at Suite 600, 1947 Center
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Street, Berkeley, California 94704. Funding was partially provided by the
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National Science Foundation under grant MIP-9311980. The original version
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of this code was written as part of a project to build a fixed-point vector
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processor in collaboration with the University of California at Berkeley,
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overseen by Profs. Nelson Morgan and John Wawrzynek. More information
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is available through the Web page
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http://www.jhauser.us/arithmetic/SoftFloat-2b/SoftFloat-source.txt
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THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort
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has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
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TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO
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PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
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AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
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Derivative works are acceptable, even for commercial purposes, so long as
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(1) they include prominent notice that the work is derivative, and (2) they
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include prominent notice akin to these three paragraphs for those parts of
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this code that are retained.
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===============================================================================
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*/
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/*
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-------------------------------------------------------------------------------
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Underflow tininess-detection mode, statically initialized to default value.
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(The declaration in `softfloat.h' must match the `int8' type here.)
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-------------------------------------------------------------------------------
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*/
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int8 float_detect_tininess = float_tininess_after_rounding;
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/*
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-------------------------------------------------------------------------------
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Raises the exceptions specified by `flags'. Floating-point traps can be
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defined here if desired. It is currently not possible for such a trap to
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substitute a result value. If traps are not implemented, this routine
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should be simply `float_exception_flags |= flags;'.
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ScottB: November 4, 1998
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Moved this function out of softfloat-specialize into fpmodule.c.
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This effectively isolates all the changes required for integrating with the
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Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying
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fpmodule.c to integrate with the NetBSD kernel (I hope!).
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-------------------------------------------------------------------------------
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void float_raise( int8 flags )
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{
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float_exception_flags |= flags;
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}
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*/
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/*
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-------------------------------------------------------------------------------
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Internal canonical NaN format.
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-------------------------------------------------------------------------------
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*/
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typedef struct {
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flag sign;
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bits64 high, low;
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} commonNaNT;
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/*
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-------------------------------------------------------------------------------
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The pattern for a default generated single-precision NaN.
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-------------------------------------------------------------------------------
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*/
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#define float32_default_nan 0xFFFFFFFF
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the single-precision floating-point value `a' is a NaN;
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otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag float32_is_nan( float32 a )
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{
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return ( 0xFF000000 < (bits32) ( a<<1 ) );
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}
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the single-precision floating-point value `a' is a signaling
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NaN; otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag float32_is_signaling_nan( float32 a )
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{
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return ( ( ( a>>22 ) & 0x1FF ) == 0x1FE ) && ( a & 0x003FFFFF );
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the single-precision floating-point NaN
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`a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
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exception is raised.
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-------------------------------------------------------------------------------
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*/
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static commonNaNT float32ToCommonNaN( float32 a )
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{
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commonNaNT z;
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if ( float32_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
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z.sign = a>>31;
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z.low = 0;
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z.high = ( (bits64) a )<<41;
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return z;
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the canonical NaN `a' to the single-
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precision floating-point format.
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-------------------------------------------------------------------------------
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*/
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static float32 commonNaNToFloat32( commonNaNT a )
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{
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return ( ( (bits32) a.sign )<<31 ) | 0x7FC00000 | ( a.high>>41 );
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}
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/*
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-------------------------------------------------------------------------------
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Takes two single-precision floating-point values `a' and `b', one of which
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is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
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signaling NaN, the invalid exception is raised.
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-------------------------------------------------------------------------------
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*/
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static float32 propagateFloat32NaN( float32 a, float32 b )
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{
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flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
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aIsNaN = float32_is_nan( a );
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aIsSignalingNaN = float32_is_signaling_nan( a );
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bIsNaN = float32_is_nan( b );
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bIsSignalingNaN = float32_is_signaling_nan( b );
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a |= 0x00400000;
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b |= 0x00400000;
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if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
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if ( aIsNaN ) {
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return ( aIsSignalingNaN & bIsNaN ) ? b : a;
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}
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else {
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return b;
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}
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}
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/*
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-------------------------------------------------------------------------------
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The pattern for a default generated double-precision NaN.
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-------------------------------------------------------------------------------
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*/
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#define float64_default_nan LIT64( 0xFFFFFFFFFFFFFFFF )
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the double-precision floating-point value `a' is a NaN;
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otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag float64_is_nan( float64 a )
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{
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return ( LIT64( 0xFFE0000000000000 ) < (bits64) ( a<<1 ) );
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}
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the double-precision floating-point value `a' is a signaling
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NaN; otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag float64_is_signaling_nan( float64 a )
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{
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return
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( ( ( a>>51 ) & 0xFFF ) == 0xFFE )
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&& ( a & LIT64( 0x0007FFFFFFFFFFFF ) );
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the double-precision floating-point NaN
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`a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
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exception is raised.
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-------------------------------------------------------------------------------
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*/
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static commonNaNT float64ToCommonNaN( float64 a )
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{
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commonNaNT z;
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if ( float64_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
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z.sign = a>>63;
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z.low = 0;
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z.high = a<<12;
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return z;
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the canonical NaN `a' to the double-
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precision floating-point format.
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-------------------------------------------------------------------------------
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*/
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static float64 commonNaNToFloat64( commonNaNT a )
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{
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return
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( ( (bits64) a.sign )<<63 )
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| LIT64( 0x7FF8000000000000 )
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| ( a.high>>12 );
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}
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/*
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-------------------------------------------------------------------------------
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Takes two double-precision floating-point values `a' and `b', one of which
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is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
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signaling NaN, the invalid exception is raised.
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-------------------------------------------------------------------------------
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*/
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static float64 propagateFloat64NaN( float64 a, float64 b )
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{
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flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
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aIsNaN = float64_is_nan( a );
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aIsSignalingNaN = float64_is_signaling_nan( a );
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bIsNaN = float64_is_nan( b );
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bIsSignalingNaN = float64_is_signaling_nan( b );
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a |= LIT64( 0x0008000000000000 );
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b |= LIT64( 0x0008000000000000 );
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if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
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if ( aIsNaN ) {
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return ( aIsSignalingNaN & bIsNaN ) ? b : a;
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}
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else {
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return b;
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}
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}
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#ifdef FLOATX80
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/*
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-------------------------------------------------------------------------------
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The pattern for a default generated extended double-precision NaN. The
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`high' and `low' values hold the most- and least-significant bits,
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respectively.
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-------------------------------------------------------------------------------
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*/
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#define floatx80_default_nan_high 0xFFFF
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#define floatx80_default_nan_low LIT64( 0xFFFFFFFFFFFFFFFF )
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the extended double-precision floating-point value `a' is a
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NaN; otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag floatx80_is_nan( floatx80 a )
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{
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return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 );
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}
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/*
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-------------------------------------------------------------------------------
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Returns 1 if the extended double-precision floating-point value `a' is a
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signaling NaN; otherwise returns 0.
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-------------------------------------------------------------------------------
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*/
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flag floatx80_is_signaling_nan( floatx80 a )
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{
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//register int lr;
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bits64 aLow;
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//__asm__("mov %0, lr" : : "g" (lr));
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//fp_printk("floatx80_is_signalling_nan() called from 0x%08x\n",lr);
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aLow = a.low & ~ LIT64( 0x4000000000000000 );
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return
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( ( a.high & 0x7FFF ) == 0x7FFF )
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&& (bits64) ( aLow<<1 )
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&& ( a.low == aLow );
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the extended double-precision floating-
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point NaN `a' to the canonical NaN format. If `a' is a signaling NaN, the
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invalid exception is raised.
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-------------------------------------------------------------------------------
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*/
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static commonNaNT floatx80ToCommonNaN( floatx80 a )
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{
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commonNaNT z;
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if ( floatx80_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
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z.sign = a.high>>15;
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z.low = 0;
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z.high = a.low<<1;
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return z;
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}
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/*
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-------------------------------------------------------------------------------
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Returns the result of converting the canonical NaN `a' to the extended
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double-precision floating-point format.
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-------------------------------------------------------------------------------
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*/
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static floatx80 commonNaNToFloatx80( commonNaNT a )
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{
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floatx80 z;
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z.low = LIT64( 0xC000000000000000 ) | ( a.high>>1 );
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z.high = ( ( (bits16) a.sign )<<15 ) | 0x7FFF;
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z.__padding = 0;
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return z;
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}
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/*
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-------------------------------------------------------------------------------
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Takes two extended double-precision floating-point values `a' and `b', one
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of which is a NaN, and returns the appropriate NaN result. If either `a' or
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`b' is a signaling NaN, the invalid exception is raised.
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-------------------------------------------------------------------------------
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*/
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static floatx80 propagateFloatx80NaN( floatx80 a, floatx80 b )
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{
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flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
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aIsNaN = floatx80_is_nan( a );
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aIsSignalingNaN = floatx80_is_signaling_nan( a );
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bIsNaN = floatx80_is_nan( b );
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bIsSignalingNaN = floatx80_is_signaling_nan( b );
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a.low |= LIT64( 0xC000000000000000 );
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b.low |= LIT64( 0xC000000000000000 );
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if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
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if ( aIsNaN ) {
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return ( aIsSignalingNaN & bIsNaN ) ? b : a;
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}
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else {
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return b;
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}
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}
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#endif
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