| 1 | /* lrint adapted to be llrint for Newlib, 2009 by Craig Howland. */ |
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| 2 | /* @(#)s_lrint.c 5.1 93/09/24 */ |
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| 3 | /* |
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| 4 | * ==================================================== |
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| 5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 6 | * |
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| 7 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 8 | * Permission to use, copy, modify, and distribute this |
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| 9 | * software is freely granted, provided that this notice |
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| 10 | * is preserved. |
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| 11 | * ==================================================== |
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| 12 | */ |
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| 13 | |
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| 14 | /* |
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| 15 | * llrint(x) |
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| 16 | * Return x rounded to integral value according to the prevailing |
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| 17 | * rounding mode. |
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| 18 | * Method: |
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| 19 | * Using floating addition. |
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| 20 | * Exception: |
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| 21 | * Inexact flag raised if x not equal to llrint(x). |
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| 22 | */ |
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| 23 | |
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| 24 | #include "fdlibm.h" |
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| 25 | |
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| 26 | #ifndef _DOUBLE_IS_32BITS |
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| 27 | |
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| 28 | #ifdef __STDC__ |
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| 29 | static const double |
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| 30 | #else |
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| 31 | static double |
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| 32 | #endif |
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| 33 | |
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| 34 | /* Adding a double, x, to 2^52 will cause the result to be rounded based on |
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| 35 | the fractional part of x, according to the implementation's current rounding |
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| 36 | mode. 2^52 is the smallest double that can be represented using all 52 significant |
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| 37 | digits. */ |
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| 38 | TWO52[2]={ |
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| 39 | 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
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| 40 | -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
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| 41 | }; |
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| 42 | |
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| 43 | long long int |
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| 44 | #ifdef __STDC__ |
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| 45 | llrint(double x) |
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| 46 | #else |
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| 47 | llrint(x) |
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| 48 | double x; |
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| 49 | #endif |
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| 50 | { |
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| 51 | __int32_t i0,j0,sx; |
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| 52 | __uint32_t i1; |
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| 53 | double t; |
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| 54 | volatile double w; |
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| 55 | long long int result; |
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| 56 | |
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| 57 | EXTRACT_WORDS(i0,i1,x); |
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| 58 | |
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| 59 | /* Extract sign bit. */ |
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| 60 | sx = (i0>>31)&1; |
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| 61 | |
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| 62 | /* Extract exponent field. */ |
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| 63 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 64 | /* j0 in [-1023,1024] */ |
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| 65 | |
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| 66 | if(j0 < 20) |
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| 67 | { |
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| 68 | /* j0 in [-1023,19] */ |
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| 69 | if(j0 < -1) |
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| 70 | return 0; |
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| 71 | else |
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| 72 | { |
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| 73 | /* j0 in [0,19] */ |
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| 74 | /* shift amt in [0,19] */ |
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| 75 | w = TWO52[sx] + x; |
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| 76 | t = w - TWO52[sx]; |
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| 77 | GET_HIGH_WORD(i0, t); |
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| 78 | /* Detect the all-zeros representation of plus and |
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| 79 | minus zero, which fails the calculation below. */ |
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| 80 | if ((i0 & ~((__int32_t)1 << 31)) == 0) |
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| 81 | return 0; |
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| 82 | /* After round: j0 in [0,20] */ |
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| 83 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 84 | i0 &= 0x000fffff; |
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| 85 | i0 |= 0x00100000; |
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| 86 | /* shift amt in [20,0] */ |
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| 87 | result = i0 >> (20 - j0); |
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| 88 | } |
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| 89 | } |
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| 90 | else if (j0 < (int)(8 * sizeof (long long int)) - 1) |
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| 91 | { |
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| 92 | /* 64bit return: j0 in [20,62] */ |
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| 93 | if (j0 >= 52) |
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| 94 | /* 64bit return: j0 in [52,62] */ |
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| 95 | /* 64bit return: left shift amt in [32,42] */ |
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| 96 | result = ((long long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) | |
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| 97 | /* 64bit return: right shift amt in [0,10] */ |
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| 98 | (i1 << (j0 - 52)); |
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| 99 | else |
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| 100 | { |
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| 101 | /* 64bit return: j0 in [20,51] */ |
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| 102 | w = TWO52[sx] + x; |
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| 103 | t = w - TWO52[sx]; |
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| 104 | EXTRACT_WORDS (i0, i1, t); |
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| 105 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 106 | i0 &= 0x000fffff; |
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| 107 | i0 |= 0x00100000; |
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| 108 | /* After round: |
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| 109 | * 64bit return: j0 in [20,52] */ |
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| 110 | /* 64bit return: left shift amt in [0,32] */ |
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| 111 | /* ***64bit return: right shift amt in [32,0] */ |
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| 112 | result = ((long long int) i0 << (j0 - 20)) |
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| 113 | | SAFE_RIGHT_SHIFT (i1, (52 - j0)); |
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| 114 | } |
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| 115 | } |
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| 116 | else |
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| 117 | { |
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| 118 | return (long long int) x; |
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| 119 | } |
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| 120 | |
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| 121 | return sx ? -result : result; |
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| 122 | } |
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| 123 | |
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| 124 | #endif /* _DOUBLE_IS_32BITS */ |
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