diff options
Diffstat (limited to 'sysdeps/ieee754/flt-32/s_sinf.c')
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_sinf.c | 177 |
1 files changed, 135 insertions, 42 deletions
diff --git a/sysdeps/ieee754/flt-32/s_sinf.c b/sysdeps/ieee754/flt-32/s_sinf.c index 916e345571..138e318dcc 100644 --- a/sysdeps/ieee754/flt-32/s_sinf.c +++ b/sysdeps/ieee754/flt-32/s_sinf.c @@ -1,25 +1,26 @@ -/* s_sinf.c -- float version of s_sin.c. - * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. - */ +/* Compute sine of argument. + Copyright (C) 2017-2018 Free Software Foundation, Inc. + This file is part of the GNU C Library. -/* - * ==================================================== - * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. - * - * Developed at SunPro, a Sun Microsystems, Inc. business. - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. -#if defined(LIBM_SCCS) && !defined(lint) -static char rcsid[] = "$NetBSD: s_sinf.c,v 1.4 1995/05/10 20:48:16 jtc Exp $"; -#endif + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ #include <errno.h> #include <math.h> #include <math_private.h> +#include <libm-alias-float.h> +#include "s_sincosf.h" #ifndef SINF # define SINF_FUNC __sinf @@ -27,37 +28,129 @@ static char rcsid[] = "$NetBSD: s_sinf.c,v 1.4 1995/05/10 20:48:16 jtc Exp $"; # define SINF_FUNC SINF #endif -float SINF_FUNC(float x) +float +SINF_FUNC (float x) { - float y[2],z=0.0; - int32_t n, ix; - - GET_FLOAT_WORD(ix,x); - - /* |x| ~< pi/4 */ - ix &= 0x7fffffff; - if(ix <= 0x3f490fd8) return __kernel_sinf(x,z,0); - - /* sin(Inf or NaN) is NaN */ - else if (ix>=0x7f800000) { - if (ix == 0x7f800000) - __set_errno (EDOM); - return x-x; + double cx; + double theta = x; + double abstheta = fabs (theta); + /* If |x|< Pi/4. */ + if (isless (abstheta, M_PI_4)) + { + if (abstheta >= 0x1p-5) /* |x| >= 2^-5. */ + { + const double theta2 = theta * theta; + /* Chebyshev polynomial of the form for sin + x+x^3*(S0+x^2*(S1+x^2*(S2+x^2*(S3+x^2*S4)))). */ + cx = S3 + theta2 * S4; + cx = S2 + theta2 * cx; + cx = S1 + theta2 * cx; + cx = S0 + theta2 * cx; + cx = theta + theta * theta2 * cx; + return cx; } - - /* argument reduction needed */ - else { - n = __ieee754_rem_pio2f(x,y); - switch(n&3) { - case 0: return __kernel_sinf(y[0],y[1],1); - case 1: return __kernel_cosf(y[0],y[1]); - case 2: return -__kernel_sinf(y[0],y[1],1); - default: - return -__kernel_cosf(y[0],y[1]); + else if (abstheta >= 0x1p-27) /* |x| >= 2^-27. */ + { + /* A simpler Chebyshev approximation is close enough for this range: + for sin: x+x^3*(SS0+x^2*SS1). */ + const double theta2 = theta * theta; + cx = SS0 + theta2 * SS1; + cx = theta + theta * theta2 * cx; + return cx; + } + else + { + /* Handle some special cases. */ + if (theta) + return theta - (theta * SMALL); + else + return theta; + } + } + else /* |x| >= Pi/4. */ + { + unsigned int signbit = isless (x, 0); + if (isless (abstheta, 9 * M_PI_4)) /* |x| < 9*Pi/4. */ + { + /* There are cases where FE_UPWARD rounding mode can + produce a result of abstheta * inv_PI_4 == 9, + where abstheta < 9pi/4, so the domain for + pio2_table must go to 5 (9 / 2 + 1). */ + unsigned int n = (abstheta * inv_PI_4) + 1; + theta = abstheta - pio2_table[n / 2]; + return reduced_sin (theta, n, signbit); + } + else if (isless (abstheta, INFINITY)) + { + if (abstheta < 0x1p+23) /* |x| < 2^23. */ + { + unsigned int n = ((unsigned int) (abstheta * inv_PI_4)) + 1; + double x = n / 2; + theta = (abstheta - x * PI_2_hi) - x * PI_2_lo; + /* Argument reduction needed. */ + return reduced_sin (theta, n, signbit); + } + else /* |x| >= 2^23. */ + { + x = fabsf (x); + int exponent; + GET_FLOAT_WORD (exponent, x); + exponent + = (exponent >> FLOAT_EXPONENT_SHIFT) - FLOAT_EXPONENT_BIAS; + exponent += 3; + exponent /= 28; + double a = invpio4_table[exponent] * x; + double b = invpio4_table[exponent + 1] * x; + double c = invpio4_table[exponent + 2] * x; + double d = invpio4_table[exponent + 3] * x; + uint64_t l = a; + l &= ~0x7; + a -= l; + double e = a + b; + l = e; + e = a - l; + if (l & 1) + { + e -= 1.0; + e += b; + e += c; + e += d; + e *= M_PI_4; + return reduced_sin (e, l + 1, signbit); + } + else + { + e += b; + e += c; + e += d; + if (e <= 1.0) + { + e *= M_PI_4; + return reduced_sin (e, l + 1, signbit); + } + else + { + l++; + e -= 2.0; + e *= M_PI_4; + return reduced_sin (e, l + 1, signbit); + } + } } } + else + { + int32_t ix; + /* High word of x. */ + GET_FLOAT_WORD (ix, abstheta); + /* Sin(Inf or NaN) is NaN. */ + if (ix == 0x7f800000) + __set_errno (EDOM); + return x - x; + } + } } #ifndef SINF -weak_alias (__sinf, sinf) +libm_alias_float (__sin, sin) #endif |