136 lines
3.2 KiB
C
136 lines
3.2 KiB
C
/*++
|
|
|
|
Copyright (c) 1999 Microsoft Corporation
|
|
|
|
Module Name:
|
|
|
|
tan.c
|
|
|
|
Abstract:
|
|
|
|
This module implement tan function used in the wow64 mscpu.
|
|
|
|
Author:
|
|
|
|
|
|
Revision History:
|
|
|
|
29-sept-1999 ATM Shafiqul Khalid [askhalid] copied from rtl library.
|
|
--*/
|
|
|
|
#include <math.h>
|
|
#include <trans.h>
|
|
|
|
/* constants */
|
|
static double const TWO_OVER_PI = 0.63661977236758134308;
|
|
static double const EPS = 1.05367121277235079465e-8; /* 2^(-53/2) */
|
|
static double const YMAX = 2.98156826864790199324e8; /* 2^(53/2)*PI/2 */
|
|
|
|
//
|
|
// The sum of C1 and C2 is a representation of PI/2 with 66 bits in the
|
|
// significand (same as x87). (PI/2 = 2 * 0.c90fdaa2 2168c234 c h)
|
|
//
|
|
|
|
static _dbl _C1 = {SET_DBL (0x3ff921fb, 0x54400000)};
|
|
static _dbl _C2 = {SET_DBL (0x3dd0b461, 0x1a600000)};
|
|
#define C1 (_C1.dbl)
|
|
#define C2 (_C2.dbl)
|
|
|
|
/* constants for the rational approximation */
|
|
/* p0 = 1.0 is not used (avoid mult by 1) */
|
|
static double const p1 = -0.13338350006421960681e+0;
|
|
static double const p2 = 0.34248878235890589960e-2;
|
|
static double const p3 = -0.17861707342254426711e-4;
|
|
static double const q0 = 0.10000000000000000000e+1;
|
|
static double const q1 = -0.46671683339755294240e+0;
|
|
static double const q2 = 0.25663832289440112864e-1;
|
|
static double const q3 = -0.31181531907010027307e-3;
|
|
static double const q4 = 0.49819433993786512270e-6;
|
|
|
|
|
|
#define Q(g) ((((q4 * (g) + q3) * (g) + q2) * (g) + q1) * (g) + q0)
|
|
#define P(g,f) (((p3 * (g) + p2) * (g) + p1) * (g) * (f) + (f))
|
|
|
|
#define ISODD(i) ((i)&0x1)
|
|
|
|
|
|
/***
|
|
*double tan(double x) - tangent
|
|
*
|
|
*Purpose:
|
|
* Compute the tangent of a number.
|
|
* The algorithm (reduction / rational approximation) is
|
|
* taken from Cody & Waite.
|
|
*
|
|
*Entry:
|
|
*
|
|
*Exit:
|
|
*
|
|
*Exceptions:
|
|
* P, I, U
|
|
* if x is denormal: raise underflow
|
|
*******************************************************************************/
|
|
double Proxytan(double x)
|
|
{
|
|
unsigned int savedcw;
|
|
unsigned long n;
|
|
double xn,xnum,xden;
|
|
double f,g,result;
|
|
|
|
/* save user fp control word */
|
|
savedcw = _maskfp();
|
|
|
|
if (IS_D_SPECIAL(x)){
|
|
switch(_sptype(x)) {
|
|
case T_PINF:
|
|
case T_NINF:
|
|
return _except1(FP_I,OP_TAN,x,QNAN_TAN1,savedcw);
|
|
case T_QNAN:
|
|
return _handle_qnan1(OP_TAN, x, savedcw);
|
|
default: //T_SNAN
|
|
return _except1(FP_I,OP_TAN,x,_s2qnan(x),savedcw);
|
|
}
|
|
}
|
|
|
|
if (x == 0.0)
|
|
RETURN(savedcw, x);
|
|
|
|
if (ABS(x) > YMAX) {
|
|
|
|
// The argument is too large to produce a meaningful result,
|
|
// so this is treated as an invalid operation.
|
|
// We also set the (extra) FP_TLOSS flag for matherr
|
|
// support
|
|
|
|
return _except1(FP_TLOSS | FP_I,OP_TAN,x,QNAN_TAN2,savedcw);
|
|
}
|
|
|
|
xn = _frnd(x * TWO_OVER_PI);
|
|
n = (unsigned long) fabs(xn);
|
|
|
|
|
|
/* assume there is a guard digit for addition */
|
|
f = (x - xn * C1) - xn * C2;
|
|
if (ABS(f) < EPS) {
|
|
xnum = f;
|
|
xden = 1;
|
|
if (IS_D_DENORM(f)) {
|
|
return _except1(FP_U | FP_P,OP_TAN,x,_add_exp(f, IEEE_ADJUST),savedcw);
|
|
}
|
|
}
|
|
else {
|
|
g = f*f;
|
|
xnum = P(g,f);
|
|
xden = Q(g);
|
|
}
|
|
|
|
if (ISODD(n)) {
|
|
xnum = -xnum;
|
|
result = xden/xnum;
|
|
}
|
|
else
|
|
result = xnum/xden;
|
|
|
|
RETURN_INEXACT1(OP_TAN,x,result,savedcw);
|
|
}
|