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| author | Adhemerval Zanella <azanella@linux.vnet.ibm.com> | 2011-09-07 22:10:26 -0400 |
|---|---|---|
| committer | Ulrich Drepper <drepper@gmail.com> | 2011-09-07 22:10:26 -0400 |
| commit | 77a2a8b4a19f0ad8d34e821a07da15d415f8f263 (patch) | |
| tree | 1e6ca46c2bb0fa92e145abdb2b90a94952d62029 /sysdeps/powerpc/fpu/e_rem_pio2f.c | |
| parent | 24f579d86e13131beb3f4823e944cc447633a2c1 (diff) | |
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Trigonometric optimizations for POWER
Diffstat (limited to 'sysdeps/powerpc/fpu/e_rem_pio2f.c')
| -rw-r--r-- | sysdeps/powerpc/fpu/e_rem_pio2f.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/sysdeps/powerpc/fpu/e_rem_pio2f.c b/sysdeps/powerpc/fpu/e_rem_pio2f.c new file mode 100644 index 0000000000..4744895f4f --- /dev/null +++ b/sysdeps/powerpc/fpu/e_rem_pio2f.c @@ -0,0 +1,190 @@ +/* e_rem_pio2f.c -- float version of e_rem_pio2.c + Copyright (C) 2011 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011 + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <math.h> + +#include "math_private.h" +#include "s_float_bitwise.h" + +/* defined in sysdeps/powerpc/fpu/k_rem_pio2f.c */ +int __fp_kernel_rem_pio2f (float *x, float *y, float e0, int32_t nx); + +/* __ieee754_rem_pio2f(x,y) + * + * return the remainder of x rem pi/2 in y[0]+y[1] + */ + +static const float npio2_hw[] = { + 1.57077026e+00, 3.14154053e+00, 4.71228027e+00, 6.28308105e+00, + 7.85388184e+00, 9.42456055e+00, 1.09953613e+01, 1.25661621e+01, + 1.41369629e+01, 1.57077637e+01, 1.72783203e+01, 1.88491211e+01, + 2.04199219e+01, 2.19907227e+01, 2.35615234e+01, 2.51323242e+01, + 2.67031250e+01, 2.82739258e+01, 2.98447266e+01, 3.14155273e+01, + 3.29863281e+01, 3.45566406e+01, 3.61279297e+01, 3.76982422e+01, + 3.92695312e+01, 4.08398438e+01, 4.24111328e+01, 4.39814453e+01, + 4.55527344e+01, 4.71230469e+01, 4.86943359e+01, 5.02646484e+01 +}; + + +static const float zero = 0.0000000000e+00; +static const float two8 = 2.5600000000e+02; + +static const float half = 5.0000000000e-01; +static const float invpio2 = 6.3661980629e-01; +static const float pio2_1 = 1.5707855225e+00; +static const float pio2_1t = 1.0804334124e-05; +static const float pio2_2 = 1.0804273188e-05; +static const float pio2_2t = 6.0770999344e-11; +static const float pio2_3 = 6.0770943833e-11; +static const float pio2_3t = 6.1232342629e-17; + +static const float pio4 = 7.8539801e-01; +static const float pio3_4 = 2.3561945e+00; +static const float pio2_24b = 1.5707951e+00; +static const float pio2_2e7 = 2.0106054e+02; + + +int32_t +__ieee754_rem_pio2f (float x, float *y) +{ + float ax, z, n, r, w, t, e0; + float tx[3]; + int32_t i, nx; + + ax = __builtin_fabsf (x); + if (ax <= pio4) + { + y[0] = x; + y[1] = 0; + return 0; + } + if (ax < pio3_4) + { + if (x > 0) + { + z = x - pio2_1; + if (!__float_and_test28 (ax, pio2_24b)) + { + y[0] = z - pio2_1t; + y[1] = (z - y[0]) - pio2_1t; + } + else + { + z -= pio2_2; + y[0] = z - pio2_2t; + y[1] = (z - y[0]) - pio2_2t; + } + return 1; + } + else + { + z = x + pio2_1; + if (!__float_and_test28 (ax, pio2_24b)) + { + y[0] = z + pio2_1t; + y[1] = (z - y[0]) + pio2_1t; + } + else + { + z += pio2_2; + y[0] = z + pio2_2t; + y[1] = (z - y[0]) + pio2_2t; + } + return -1; + } + } + if (ax <= pio2_2e7) + { + n = floorf (ax * invpio2 + half); + i = (int32_t) n; + r = ax - n * pio2_1; + w = n * pio2_1t; /* 1st round good to 40 bit */ + if (i < 32 && !__float_and_test24 (ax, npio2_hw[i - 1])) + { + y[0] = r - w; + } + else + { + float i, j; + j = __float_and8 (ax); + y[0] = r - w; + i = __float_and8 (y[0]); + if (j / i > 256.0 || j / i < 3.9062500e-3) + { /* 2nd iterations needed, good to 57 */ + t = r; + w = n * pio2_2; + r = t - w; + w = n * pio2_2t - ((t - r) - w); + y[0] = r - w; + i = __float_and8 (y[0]); + if (j / i > 33554432 || j / i < 2.9802322e-8) + { /* 3rd iteration needed, 74 bits acc */ + t = r; + w = n * pio2_3; + r = t - w; + w = n * pio2_3t - ((t - r) - w); + y[0] = r - w; + } + } + } + y[1] = (r - y[0]) - w; + if (x < 0) + { + y[0] = -y[0]; + y[1] = -y[1]; + return -i; + } + else + { + return i; + } + } + + /* all other (large) arguments */ + if (isnanf (x) || isinff (x)) + { + y[0] = y[1] = x - x; + return 0; + } + + /* set z = scalbn(|x|,ilogb(x)-7) */ + e0 = __float_and8 (ax / 128.0); + z = ax / e0; + + tx[0] = floorf (z); + z = (z - tx[0]) * two8; + tx[1] = floorf (z); + z = (z - tx[1]) * two8; + tx[2] = floorf (z); + + nx = 3; + while (tx[nx - 1] == zero) + nx--; + + i = __fp_kernel_rem_pio2f (tx, y, e0, nx); + if (x < 0) + { + y[0] = -y[0]; + y[1] = -y[1]; + return -i; + } + return i; +} + |