| 1 | /* lrintf adapted to be llrintf for Newlib, 2009 by Craig Howland. */ |
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| 2 | /* @(#)sf_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 | * llrintf(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 llrintf(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 | #ifdef __STDC__ |
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| 27 | static const float |
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| 28 | #else |
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| 29 | static float |
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| 30 | #endif |
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| 31 | /* Adding a float, x, to 2^23 will cause the result to be rounded based on |
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| 32 | the fractional part of x, according to the implementation's current rounding |
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| 33 | mode. 2^23 is the smallest float that can be represented using all 23 significant |
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| 34 | digits. */ |
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| 35 | TWO23[2]={ |
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| 36 | 8.3886080000e+06, /* 0x4b000000 */ |
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| 37 | -8.3886080000e+06, /* 0xcb000000 */ |
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| 38 | }; |
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| 39 | |
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| 40 | #ifdef __STDC__ |
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| 41 | long long int llrintf(float x) |
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| 42 | #else |
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| 43 | long long int llrintf(x) |
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| 44 | float x; |
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| 45 | #endif |
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| 46 | { |
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| 47 | __int32_t j0,sx; |
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| 48 | __uint32_t i0; |
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| 49 | float t; |
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| 50 | volatile float w; |
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| 51 | long long int result; |
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| 52 | |
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| 53 | GET_FLOAT_WORD(i0,x); |
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| 54 | |
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| 55 | /* Extract sign bit. */ |
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| 56 | sx = (i0 >> 31); |
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| 57 | |
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| 58 | /* Extract exponent field. */ |
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| 59 | j0 = ((i0 & 0x7f800000) >> 23) - 127; |
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| 60 | |
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| 61 | if (j0 < (int)(sizeof (long long int) * 8) - 1) |
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| 62 | { |
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| 63 | if (j0 < -1) |
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| 64 | return 0; |
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| 65 | else if (j0 >= 23) |
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| 66 | result = (long long int) ((i0 & 0x7fffff) | 0x800000) << (j0 - 23); |
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| 67 | else |
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| 68 | { |
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| 69 | w = TWO23[sx] + x; |
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| 70 | t = w - TWO23[sx]; |
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| 71 | GET_FLOAT_WORD (i0, t); |
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| 72 | /* Detect the all-zeros representation of plus and |
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| 73 | minus zero, which fails the calculation below. */ |
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| 74 | if ((i0 & ~((__uint32_t)1 << 31)) == 0) |
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| 75 | return 0; |
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| 76 | j0 = ((i0 >> 23) & 0xff) - 0x7f; |
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| 77 | i0 &= 0x7fffff; |
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| 78 | i0 |= 0x800000; |
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| 79 | result = i0 >> (23 - j0); |
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| 80 | } |
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| 81 | } |
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| 82 | else |
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| 83 | { |
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| 84 | return (long long int) x; |
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| 85 | } |
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| 86 | return sx ? -result : result; |
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| 87 | } |
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| 88 | |
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| 89 | #ifdef _DOUBLE_IS_32BITS |
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| 90 | |
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| 91 | #ifdef __STDC__ |
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| 92 | long long int llrint(double x) |
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| 93 | #else |
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| 94 | long long int llrint(x) |
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| 95 | double x; |
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| 96 | #endif |
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| 97 | { |
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| 98 | return llrintf((float) x); |
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| 99 | } |
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| 100 | |
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| 101 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
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