mirror of
https://github.com/fluencelabs/musl
synced 2025-06-05 11:01:37 +00:00
0cbb654791
zero, one, two, half are replaced by const literals The policy was to use the f suffix for float consts (1.0f), but don't use suffix for long double consts (these consts can be exactly represented as double).
93 lines
2.6 KiB
C
93 lines
2.6 KiB
C
/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2f.c */
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/*
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include "libm.h"
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static const volatile float
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tiny = 1.0e-30;
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static const float
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pi_o_4 = 7.8539818525e-01, /* 0x3f490fdb */
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pi_o_2 = 1.5707963705e+00, /* 0x3fc90fdb */
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pi = 3.1415927410e+00; /* 0x40490fdb */
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static const volatile float
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pi_lo = -8.7422776573e-08; /* 0xb3bbbd2e */
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float atan2f(float y, float x)
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{
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float z;
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int32_t k,m,hx,hy,ix,iy;
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GET_FLOAT_WORD(hx, x);
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ix = hx & 0x7fffffff;
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GET_FLOAT_WORD(hy, y);
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iy = hy & 0x7fffffff;
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if (ix > 0x7f800000 || iy > 0x7f800000) /* x or y is NaN */
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return x+y;
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if (hx == 0x3f800000) /* x=1.0 */
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return atanf(y);
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m = ((hy>>31)&1) | ((hx>>30)&2); /* 2*sign(x)+sign(y) */
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/* when y = 0 */
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if (iy == 0) {
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switch (m) {
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case 0:
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case 1: return y; /* atan(+-0,+anything)=+-0 */
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case 2: return pi+tiny; /* atan(+0,-anything) = pi */
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case 3: return -pi-tiny; /* atan(-0,-anything) =-pi */
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}
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}
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/* when x = 0 */
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if (ix == 0)
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return hy < 0 ? -pi_o_2-tiny : pi_o_2+tiny;
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/* when x is INF */
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if (ix == 0x7f800000) {
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if (iy == 0x7f800000) {
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switch (m) {
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case 0: return pi_o_4+tiny; /* atan(+INF,+INF) */
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case 1: return -pi_o_4-tiny; /* atan(-INF,+INF) */
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case 2: return 3.0f*pi_o_4+tiny; /*atan(+INF,-INF)*/
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case 3: return -3.0f*pi_o_4-tiny; /*atan(-INF,-INF)*/
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}
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} else {
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switch (m) {
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case 0: return 0.0f; /* atan(+...,+INF) */
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case 1: return -0.0f; /* atan(-...,+INF) */
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case 2: return pi+tiny; /* atan(+...,-INF) */
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case 3: return -pi-tiny; /* atan(-...,-INF) */
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}
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}
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}
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/* when y is INF */
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if (iy == 0x7f800000)
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return hy < 0 ? -pi_o_2-tiny : pi_o_2+tiny;
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/* compute y/x */
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k = (iy-ix)>>23;
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if (k > 26) { /* |y/x| > 2**26 */
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z = pi_o_2 + 0.5f*pi_lo;
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m &= 1;
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} else if (k < -26 && hx < 0) /* 0 > |y|/x > -2**-26 */
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z = 0.0;
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else /* safe to do y/x */
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z = atanf(fabsf(y/x));
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switch (m) {
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case 0: return z; /* atan(+,+) */
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case 1: return -z; /* atan(-,+) */
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case 2: return pi - (z-pi_lo); /* atan(+,-) */
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default: /* case 3 */
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return (z-pi_lo) - pi; /* atan(-,-) */
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}
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}
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