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Implement inverse trigonometric functions (i.e., FACOS, FASIN, FATAN 

instructions).
o arccos is calculated using arcsin.
o arcsin is calculated using arctan.
o arctan is calculated by the CORDIC.
This commit is contained in:
isaki 2013-04-19 13:57:52 +00:00
parent 92551f8725
commit b9e60bfea4
1 changed files with 99 additions and 7 deletions
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106
sys/arch/m68k/fpe/fpu_trig.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: fpu_trig.c,v 1.11 2013/04/19 13:31:11 isaki Exp $ */
/* $NetBSD: fpu_trig.c,v 1.12 2013/04/19 13:57:52 isaki Exp $ */
/*
* Copyright (c) 1995 Ken Nakata
@ -57,28 +57,120 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: fpu_trig.c,v 1.11 2013/04/19 13:31:11 isaki Exp $");
__KERNEL_RCSID(0, "$NetBSD: fpu_trig.c,v 1.12 2013/04/19 13:57:52 isaki Exp $");
#include "fpu_emulate.h"
/*
* arccos(x) = pi/2 - arcsin(x)
*/
struct fpn *
fpu_acos(struct fpemu *fe)
{
/* stub */
return &fe->fe_f2;
struct fpn *r;
if (ISNAN(&fe->fe_f2))
return &fe->fe_f2;
if (ISINF(&fe->fe_f2))
return fpu_newnan(fe);
r = fpu_asin(fe);
CPYFPN(&fe->fe_f2, r);
/* pi/2 - asin(x) */
fpu_const(&fe->fe_f1, FPU_CONST_PI);
fe->fe_f1.fp_exp--;
fe->fe_f2.fp_sign = !fe->fe_f2.fp_sign;
r = fpu_add(fe);
return r;
}
/*
* x
* arcsin(x) = arctan(---------------)
* sqrt(1 - x^2)
*/
struct fpn *
fpu_asin(struct fpemu *fe)
{
/* stub */
return &fe->fe_f2;
struct fpn x;
struct fpn *r;
if (ISNAN(&fe->fe_f2))
return &fe->fe_f2;
if (ISZERO(&fe->fe_f2))
return &fe->fe_f2;
if (ISINF(&fe->fe_f2))
return fpu_newnan(fe);
CPYFPN(&x, &fe->fe_f2);
/* x^2 */
CPYFPN(&fe->fe_f1, &fe->fe_f2);
r = fpu_mul(fe);
/* 1 - x^2 */
CPYFPN(&fe->fe_f2, r);
fe->fe_f2.fp_sign = 1;
fpu_const(&fe->fe_f1, FPU_CONST_1);
r = fpu_add(fe);
/* sqrt(1-x^2) */
CPYFPN(&fe->fe_f2, r);
r = fpu_sqrt(fe);
/* x/sqrt */
CPYFPN(&fe->fe_f2, r);
CPYFPN(&fe->fe_f1, &x);
r = fpu_div(fe);
/* arctan */
CPYFPN(&fe->fe_f2, r);
return fpu_atan(fe);
}
/*
* arctan(x):
*
* if (x < 0) {
* x = abs(x);
* sign = 1;
* }
* y = arctan(x);
* if (sign) {
* y = -y;
* }
*/
struct fpn *
fpu_atan(struct fpemu *fe)
{
/* stub */
struct fpn a;
struct fpn x;
struct fpn v;
if (ISNAN(&fe->fe_f2))
return &fe->fe_f2;
if (ISZERO(&fe->fe_f2))
return &fe->fe_f2;
CPYFPN(&a, &fe->fe_f2);
if (ISINF(&fe->fe_f2)) {
/* f2 <- pi/2 */
fpu_const(&fe->fe_f2, FPU_CONST_PI);
fe->fe_f2.fp_exp--;
fe->fe_f2.fp_sign = a.fp_sign;
return &fe->fe_f2;
}
fpu_const(&x, FPU_CONST_1);
fpu_const(&fe->fe_f2, FPU_CONST_0);
CPYFPN(&v, &fe->fe_f2);
fpu_cordit1(fe, &x, &a, &fe->fe_f2, &v);
return &fe->fe_f2;
}