92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
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/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2l.c */
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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 SunSoft, 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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*/
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/*
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* See comments in atan2.c.
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* Converted to long double by David Schultz <das@FreeBSD.ORG>.
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*/
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#include "libc/math/__invtrigl.h"
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#include "libc/math/libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double atan2l(long double y, long double x) { return atan2(y, x); }
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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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long double atan2l(long double y, long double x) {
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union ldshape ux, uy;
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long double z;
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int m, ex, ey;
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if (isnan(x) || isnan(y)) return x + y;
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if (x == 1) return atanl(y);
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ux.f = x;
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uy.f = y;
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ex = ux.i.se & 0x7fff;
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ey = uy.i.se & 0x7fff;
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m = 2 * (ux.i.se >> 15) | uy.i.se >> 15;
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if (y == 0) {
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switch (m) {
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case 0:
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case 1:
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return y; /* atan(+-0,+anything)=+-0 */
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case 2:
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return 2 * pio2_hi; /* atan(+0,-anything) = pi */
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case 3:
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return -2 * pio2_hi; /* atan(-0,-anything) =-pi */
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}
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}
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if (x == 0) return m & 1 ? -pio2_hi : pio2_hi;
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if (ex == 0x7fff) {
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if (ey == 0x7fff) {
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switch (m) {
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case 0:
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return pio2_hi / 2; /* atan(+INF,+INF) */
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case 1:
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return -pio2_hi / 2; /* atan(-INF,+INF) */
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case 2:
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return 1.5 * pio2_hi; /* atan(+INF,-INF) */
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case 3:
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return -1.5 * pio2_hi; /* atan(-INF,-INF) */
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}
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} else {
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switch (m) {
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case 0:
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return 0.0; /* atan(+...,+INF) */
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case 1:
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return -0.0; /* atan(-...,+INF) */
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case 2:
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return 2 * pio2_hi; /* atan(+...,-INF) */
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case 3:
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return -2 * pio2_hi; /* atan(-...,-INF) */
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}
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}
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}
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if (ex + 120 < ey || ey == 0x7fff) return m & 1 ? -pio2_hi : pio2_hi;
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/* z = atan(|y/x|) without spurious underflow */
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if ((m & 2) && ey + 120 < ex) /* |y/x| < 0x1p-120, x<0 */
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z = 0.0;
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else
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z = atanl(fabsl(y / x));
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switch (m) {
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case 0:
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return z; /* atan(+,+) */
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case 1:
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return -z; /* atan(-,+) */
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case 2:
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return 2 * __pio2_hi - (z - 2 * pio2_lo); /* atan(+,-) */
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default: /* case 3 */
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return (z - 2 * __pio2_lo) - 2 * pio2_hi; /* atan(-,-) */
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}
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}
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#endif
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