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| 4349 | Serge | 1 | |
| 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 SunPro, 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 | FUNCTION |
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| 14 | < |
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| 15 | INDEX |
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| 16 | lrint |
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| 17 | INDEX |
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| 18 | lrintf |
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| 19 | INDEX |
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| 20 | llrint |
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| 21 | INDEX |
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| 22 | llrintf |
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| 23 | |||
| 24 | |||
| 25 | #include |
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| 26 | long int lrint(double <[x]>); |
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| 27 | long int lrintf(float <[x]>); |
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| 28 | long long int llrint(double <[x]>); |
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| 29 | long long int llrintf(float <[x]>); |
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| 30 | |||
| 31 | |||
| 32 | The < |
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| 33 | integer value, using the current rounding direction. If the rounded value is |
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| 34 | outside the range of the return type, the numeric result is unspecified. A |
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| 35 | range error may occur if the magnitude of <[x]> is too large. |
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| 36 | The "inexact" floating-point exception is raised in implementations that |
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| 37 | support it when the result differs in value from the argument (i.e., when |
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| 38 | a fraction actually has been truncated). |
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| 39 | |||
| 40 | |||
| 41 | <[x]> rounded to an integral value, using the current rounding direction. |
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| 42 | |||
| 43 | |||
| 44 | < |
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| 45 | |||
| 46 | |||
| 47 | ANSI C, POSIX |
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| 48 | |||
| 49 | |||
| 50 | |||
| 51 | |||
| 52 | * lrint(x) |
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| 53 | * Return x rounded to integral value according to the prevailing |
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| 54 | * rounding mode. |
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| 55 | * Method: |
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| 56 | * Using floating addition. |
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| 57 | * Exception: |
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| 58 | * Inexact flag raised if x not equal to lrint(x). |
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| 59 | */ |
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| 60 | |||
| 61 | |||
| 62 | |||
| 63 | |||
| 64 | |||
| 65 | |||
| 66 | static const double |
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| 67 | #else |
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| 68 | static double |
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| 69 | #endif |
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| 70 | |||
| 71 | |||
| 72 | the fractional part of x, according to the implementation's current rounding |
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| 73 | mode. 2^52 is the smallest double that can be represented using all 52 significant |
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| 74 | digits. */ |
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| 75 | TWO52[2]={ |
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| 76 | 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
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| 77 | -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
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| 78 | }; |
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| 79 | |||
| 80 | |||
| 81 | long int lrint(double x) |
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| 82 | #else |
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| 83 | long int lrint(x) |
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| 84 | double x; |
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| 85 | #endif |
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| 86 | { |
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| 87 | __int32_t i0,j0,sx; |
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| 88 | __uint32_t i1; |
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| 89 | double t; |
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| 90 | volatile double w; |
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| 91 | long int result; |
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| 92 | |||
| 93 | |||
| 94 | |||
| 95 | |||
| 96 | sx = (i0>>31)&1; |
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| 97 | |||
| 98 | |||
| 99 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 100 | /* j0 in [-1023,1024] */ |
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| 101 | |||
| 102 | |||
| 103 | { |
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| 104 | /* j0 in [-1023,19] */ |
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| 105 | if(j0 < -1) |
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| 106 | return 0; |
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| 107 | else |
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| 108 | { |
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| 109 | /* j0 in [0,19] */ |
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| 110 | /* shift amt in [0,19] */ |
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| 111 | w = TWO52[sx] + x; |
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| 112 | t = w - TWO52[sx]; |
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| 113 | GET_HIGH_WORD(i0, t); |
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| 114 | /* Detect the all-zeros representation of plus and |
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| 115 | minus zero, which fails the calculation below. */ |
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| 116 | if ((i0 & ~(1L << 31)) == 0) |
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| 117 | return 0; |
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| 118 | /* After round: j0 in [0,20] */ |
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| 119 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 120 | i0 &= 0x000fffff; |
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| 121 | i0 |= 0x00100000; |
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| 122 | /* shift amt in [20,0] */ |
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| 123 | result = i0 >> (20 - j0); |
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| 124 | } |
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| 125 | } |
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| 126 | else if (j0 < (int)(8 * sizeof (long int)) - 1) |
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| 127 | { |
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| 128 | /* 32bit return: j0 in [20,30] */ |
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| 129 | /* 64bit return: j0 in [20,62] */ |
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| 130 | if (j0 >= 52) |
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| 131 | /* 64bit return: j0 in [52,62] */ |
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| 132 | /* 64bit return: left shift amt in [32,42] */ |
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| 133 | result = ((long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) | |
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| 134 | /* 64bit return: right shift amt in [0,10] */ |
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| 135 | (i1 << (j0 - 52)); |
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| 136 | else |
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| 137 | { |
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| 138 | /* 32bit return: j0 in [20,30] */ |
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| 139 | /* 64bit return: j0 in [20,51] */ |
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| 140 | w = TWO52[sx] + x; |
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| 141 | t = w - TWO52[sx]; |
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| 142 | EXTRACT_WORDS (i0, i1, t); |
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| 143 | j0 = ((i0 & 0x7ff00000) >> 20) - 1023; |
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| 144 | i0 &= 0x000fffff; |
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| 145 | i0 |= 0x00100000; |
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| 146 | /* After round: |
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| 147 | * 32bit return: j0 in [20,31]; |
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| 148 | * 64bit return: j0 in [20,52] */ |
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| 149 | /* 32bit return: left shift amt in [0,11] */ |
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| 150 | /* 64bit return: left shift amt in [0,32] */ |
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| 151 | /* ***32bit return: right shift amt in [32,21] */ |
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| 152 | /* ***64bit return: right shift amt in [32,0] */ |
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| 153 | result = ((long int) i0 << (j0 - 20)) |
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| 154 | | SAFE_RIGHT_SHIFT (i1, (52 - j0)); |
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| 155 | } |
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| 156 | } |
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| 157 | else |
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| 158 | { |
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| 159 | return (long int) x; |
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| 160 | } |
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| 161 | |||
| 162 | |||
| 163 | } |
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| 164 | |||
| 165 | |||
| 166 |