mirror of
https://github.com/deadw00d/AROS.git
synced 2025-12-06 21:40:57 +00:00
85 lines
1.8 KiB
C
85 lines
1.8 KiB
C
/*
|
|
Copyright (C) 1995-2003, The AROS Development Team. All rights reserved.
|
|
*/
|
|
|
|
#include "mathtrans_intern.h"
|
|
|
|
/*****************************************************************************
|
|
|
|
NAME */
|
|
|
|
AROS_LH1(float, SPTanh,
|
|
|
|
/* SYNOPSIS */
|
|
AROS_LHA(float, fnum1, D0),
|
|
|
|
/* LOCATION */
|
|
struct Library *, MathTransBase, 12, MathTrans)
|
|
|
|
/* FUNCTION
|
|
Calculate hyperbolic tangens of the ffp number
|
|
|
|
INPUTS
|
|
|
|
RESULT
|
|
Motorola fast floating point number
|
|
|
|
flags:
|
|
zero : result is zero
|
|
negative : result is negative
|
|
overflow : (not possible)
|
|
|
|
BUGS
|
|
|
|
INTERNALS
|
|
( e^x - e^(-x) )
|
|
tanh(x) = ----------------
|
|
( e^x + e^(-x) )
|
|
|
|
tanh( |x| > 9 ) = 1
|
|
|
|
*****************************************************************************/
|
|
{
|
|
AROS_LIBFUNC_INIT
|
|
|
|
ULONG Res;
|
|
LONG tmp;
|
|
|
|
tmp = (fnum1 & FFPExponent_Mask) - 0x41;
|
|
|
|
if ( tmp >= 3 && (fnum1 & FFPMantisse_Mask) >= 0x90000000 )
|
|
{
|
|
/*
|
|
tanh( x > 9 ) = 1
|
|
tanh( x <-9 ) = -1
|
|
*/
|
|
return (one | ( fnum1 & FFPSign_Mask ));
|
|
}
|
|
|
|
/* tanh(-x) = -tanh(x) */
|
|
Res = SPExp(fnum1 & (FFPMantisse_Mask + FFPExponent_Mask ));
|
|
Res = SPDiv
|
|
(
|
|
SPAdd(Res, SPDiv(Res, one)),
|
|
SPAdd(Res, (ULONG)SPDiv(Res, one) | FFPSign_Mask )
|
|
);
|
|
|
|
/* Result is zero */
|
|
if (0 == Res )
|
|
{
|
|
SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
|
|
return 0;
|
|
}
|
|
|
|
/* Argument is negative -> result is negative */
|
|
if ( (char) fnum1 < 0)
|
|
{
|
|
SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
|
|
return (Res | FFPSign_Mask );
|
|
}
|
|
|
|
return Res;
|
|
|
|
AROS_LIBFUNC_EXIT
|
|
}
|