[388] | 1 | /* origin: FreeBSD /usr/src/lib/msun/src/e_acosl.c */
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| 2 | /*
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| 3 | * ====================================================
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| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 5 | *
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| 6 | * Developed at SunSoft, a Sun Microsystems, Inc. business.
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| 7 | * Permission to use, copy, modify, and distribute this
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| 8 | * software is freely granted, provided that this notice
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| 9 | * is preserved.
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| 10 | * ====================================================
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| 11 | */
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| 12 | /*
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| 13 | * See comments in acos.c.
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| 14 | * Converted to long double by David Schultz <das@FreeBSD.ORG>.
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| 15 | */
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| 16 |
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| 17 | #include "libm.h"
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| 18 |
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| 19 | #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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| 20 | long double acosl(long double x)
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| 21 | {
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| 22 | return acos(x);
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| 23 | }
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| 24 | #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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| 25 | #include "__invtrigl.h"
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| 26 | #if LDBL_MANT_DIG == 64
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| 27 | #define CLEARBOTTOM(u) (u.i.m &= -1ULL << 32)
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| 28 | #elif LDBL_MANT_DIG == 113
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| 29 | #define CLEARBOTTOM(u) (u.i.lo = 0)
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| 30 | #endif
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| 31 |
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| 32 | long double acosl(long double x)
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| 33 | {
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| 34 | union ldshape u = {x};
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| 35 | long double z, s, c, f;
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| 36 | uint16_t e = u.i.se & 0x7fff;
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| 37 |
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| 38 | /* |x| >= 1 or nan */
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| 39 | if (e >= 0x3fff) {
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| 40 | if (x == 1)
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| 41 | return 0;
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| 42 | if (x == -1)
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| 43 | return 2*pio2_hi + 0x1p-120f;
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| 44 | return 0/(x-x);
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| 45 | }
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| 46 | /* |x| < 0.5 */
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| 47 | if (e < 0x3fff - 1) {
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| 48 | if (e < 0x3fff - LDBL_MANT_DIG - 1)
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| 49 | return pio2_hi + 0x1p-120f;
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| 50 | return pio2_hi - (__invtrigl_R(x*x)*x - pio2_lo + x);
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| 51 | }
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| 52 | /* x < -0.5 */
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| 53 | if (u.i.se >> 15) {
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| 54 | z = (1 + x)*0.5;
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| 55 | s = sqrtl(z);
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| 56 | return 2*(pio2_hi - (__invtrigl_R(z)*s - pio2_lo + s));
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| 57 | }
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| 58 | /* x > 0.5 */
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| 59 | z = (1 - x)*0.5;
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| 60 | s = sqrtl(z);
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| 61 | u.f = s;
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| 62 | CLEARBOTTOM(u);
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| 63 | f = u.f;
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| 64 | c = (z - f*f)/(s + f);
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| 65 | return 2*(__invtrigl_R(z)*s + c + f);
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| 66 | }
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| 67 | #endif
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