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| 2 | /* @(#)s_floor.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 | FUNCTION
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| 16 | <<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling
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| 17 | INDEX
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| 18 | floor
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| 19 | INDEX
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| 20 | floorf
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| 21 | INDEX
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| 22 | ceil
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| 23 | INDEX
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| 24 | ceilf
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| 25 |
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| 26 | ANSI_SYNOPSIS
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| 27 | #include <math.h>
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| 28 | double floor(double <[x]>);
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| 29 | float floorf(float <[x]>);
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| 30 | double ceil(double <[x]>);
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| 31 | float ceilf(float <[x]>);
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| 32 |
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| 33 | TRAD_SYNOPSIS
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| 34 | #include <math.h>
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| 35 | double floor(<[x]>)
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| 36 | double <[x]>;
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| 37 | float floorf(<[x]>)
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| 38 | float <[x]>;
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| 39 | double ceil(<[x]>)
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| 40 | double <[x]>;
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| 41 | float ceilf(<[x]>)
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| 42 | float <[x]>;
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| 43 |
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| 44 | DESCRIPTION
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| 45 | <<floor>> and <<floorf>> find
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| 46 | @tex
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| 47 | $\lfloor x \rfloor$,
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| 48 | @end tex
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| 49 | the nearest integer less than or equal to <[x]>.
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| 50 | <<ceil>> and <<ceilf>> find
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| 51 | @tex
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| 52 | $\lceil x\rceil$,
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| 53 | @end tex
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| 54 | the nearest integer greater than or equal to <[x]>.
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| 55 |
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| 56 | RETURNS
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| 57 | <<floor>> and <<ceil>> return the integer result as a double.
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| 58 | <<floorf>> and <<ceilf>> return the integer result as a float.
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| 59 |
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| 60 | PORTABILITY
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| 61 | <<floor>> and <<ceil>> are ANSI.
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| 62 | <<floorf>> and <<ceilf>> are extensions.
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| 63 |
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| 64 |
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| 65 | */
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| 66 |
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| 67 | /*
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| 68 | * floor(x)
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| 69 | * Return x rounded toward -inf to integral value
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| 70 | * Method:
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| 71 | * Bit twiddling.
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| 72 | * Exception:
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| 73 | * Inexact flag raised if x not equal to floor(x).
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| 74 | */
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| 75 |
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| 76 | #include "fdlibm.h"
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| 77 |
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| 78 | #ifndef _DOUBLE_IS_32BITS
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| 79 |
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| 80 | #ifdef __STDC__
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| 81 | static const double huge = 1.0e300;
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| 82 | #else
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| 83 | static double huge = 1.0e300;
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| 84 | #endif
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| 85 |
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| 86 | #ifdef __STDC__
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| 87 | double floor(double x)
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| 88 | #else
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| 89 | double floor(x)
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| 90 | double x;
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| 91 | #endif
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| 92 | {
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| 93 | int32_t i0,i1,j0;
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| 94 | uint32_t i,j;
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| 95 | EXTRACT_WORDS(i0,i1,x);
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| 96 | j0 = ((i0>>20)&0x7ff)-0x3ff;
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| 97 | if(j0<20) {
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| 98 | if(j0<0) { /* raise inexact if x != 0 */
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| 99 | if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
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| 100 | if(i0>=0) {i0=i1=0;}
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| 101 | else if(((i0&0x7fffffff)|i1)!=0)
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| 102 | { i0=0xbff00000;i1=0;}
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| 103 | }
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| 104 | } else {
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| 105 | i = (0x000fffff)>>j0;
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| 106 | if(((i0&i)|i1)==0) return x; /* x is integral */
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| 107 | if(huge+x>0.0) { /* raise inexact flag */
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| 108 | if(i0<0) i0 += (0x00100000)>>j0;
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| 109 | i0 &= (~i); i1=0;
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| 110 | }
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| 111 | }
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| 112 | } else if (j0>51) {
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| 113 | if(j0==0x400) return x+x; /* inf or NaN */
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| 114 | else return x; /* x is integral */
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| 115 | } else {
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| 116 | i = ((uint32_t)(0xffffffff))>>(j0-20);
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| 117 | if((i1&i)==0) return x; /* x is integral */
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| 118 | if(huge+x>0.0) { /* raise inexact flag */
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| 119 | if(i0<0) {
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| 120 | if(j0==20) i0+=1;
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| 121 | else {
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| 122 | j = i1+(1<<(52-j0));
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| 123 | if(j<(uint32_t)i1) i0 +=1 ; /* got a carry */
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| 124 | i1=j;
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| 125 | }
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| 126 | }
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| 127 | i1 &= (~i);
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| 128 | }
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| 129 | }
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| 130 | INSERT_WORDS(x,i0,i1);
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| 131 | return x;
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| 132 | }
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| 133 |
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| 134 | #endif /* _DOUBLE_IS_32BITS */
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