| 1 | /*
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| 2 | * ====================================================
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| 3 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 4 | *
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| 5 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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| 6 | * Permission to use, copy, modify, and distribute this
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| 7 | * software is freely granted, provided that this notice
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| 8 | * is preserved.
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| 9 | * ====================================================
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| 10 | */
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| 11 |
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| 12 | /*
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| 13 | * Modified for ALMOS-MKH OS at UPMC, France, August 2018. (Alain Greiner)
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| 14 | */
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| 15 |
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| 16 | /*
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| 17 | * floor(x)
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| 18 | * Return x rounded toward -inf to integral value
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| 19 | * Method:
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| 20 | * Bit twiddling.
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| 21 | * Exception:
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| 22 | * Inexact flag raised if x not equal to floor(x).
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| 23 | */
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| 24 |
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| 25 | #include "math.h"
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| 26 | #include "math_private.h"
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| 27 |
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| 28 | static const double huge = 1.0e300;
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| 29 |
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| 30 | double floor(double x)
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| 31 | {
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| 32 | int32_t i0, i1, j0;
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| 33 | uint32_t i, j;
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| 34 | EXTRACT_WORDS(i0, i1, x);
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| 35 | j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
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| 36 | if (j0 < 20) {
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| 37 | if (j0 < 0) { /* raise inexact if x != 0 */
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| 38 | if (huge + x > 0.0) {/* return 0*sign(x) if |x|<1 */
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| 39 | if (i0 >= 0) {
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| 40 | i0 = i1 = 0;
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| 41 | }
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| 42 | else if (((i0 & 0x7fffffff) | i1) != 0) {
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| 43 | i0 = 0xbff00000;
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| 44 | i1 = 0;
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| 45 | }
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| 46 | }
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| 47 | }
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| 48 | else {
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| 49 | i = (0x000fffff) >> j0;
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| 50 | if (((i0 & i) | i1) == 0) {
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| 51 | return x; /* x is integral */
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| 52 | }
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| 53 | if (huge + x > 0.0) { /* raise inexact flag */
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| 54 | if (i0 < 0) {
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| 55 | i0 += (0x00100000) >> j0;
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| 56 | }
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| 57 | i0 &= (~i);
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| 58 | i1 = 0;
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| 59 | }
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| 60 | }
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| 61 | }
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| 62 | else if (j0 > 51) {
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| 63 | if (j0 == 0x400) {
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| 64 | return x + x; /* inf or NaN */
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| 65 | }
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| 66 | else {
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| 67 | return x; /* x is integral */
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| 68 | }
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| 69 | }
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| 70 | else {
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| 71 | i = ((uint32_t) (0xffffffff)) >> (j0 - 20);
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| 72 | if ((i1 & i)== 0) {
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| 73 | return x; /* x is integral */
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| 74 | }
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| 75 | if (huge + x > 0.0) { /* raise inexact flag */
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| 76 | if (i0 < 0) {
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| 77 | if (j0 == 20) {
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| 78 | i0 += 1;
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| 79 | }
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| 80 | else {
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| 81 | j = i1 + (1 << (52 - j0));
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| 82 | if (j < i1) {
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| 83 | i0 += 1 ; /* got a carry */
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| 84 | }
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| 85 | i1 = j;
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| 86 | }
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| 87 | }
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| 88 | i1 &= (~i);
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| 89 | }
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| 90 | }
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| 91 | INSERT_WORDS(x, i0, i1);
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| 92 | return x;
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| 93 | }
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| 94 |
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