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| Rev | Author | Line No. | Line |
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| 2 | pj | 1 | /* @(#)s_floor.c 5.1 93/09/24 */ |
| 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 | |||
| 13 | #ifndef lint |
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| 14 | static char rcsid[] = "$\Id: s_floor.c,v 1.2.6.1 1997/02/23 11:03:18 joerg Exp $"; |
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| 15 | #endif |
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| 16 | |||
| 17 | /* |
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| 18 | * floor(x) |
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| 19 | * Return x rounded toward -inf to integral value |
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| 20 | * Method: |
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| 21 | * Bit twiddling. |
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| 22 | * Exception: |
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| 23 | * Inexact flag raised if x not equal to floor(x). |
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| 24 | */ |
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| 25 | |||
| 26 | #include "math.h" |
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| 27 | #include "math_private.h" |
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| 28 | |||
| 29 | #ifdef __STDC__ |
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| 30 | static const double huge = 1.0e300; |
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| 31 | #else |
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| 32 | static double huge = 1.0e300; |
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| 33 | #endif |
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| 34 | |||
| 35 | #ifdef __STDC__ |
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| 36 | double __generic_floor(double x) |
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| 37 | #else |
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| 38 | double __generic_floor(x) |
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| 39 | double x; |
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| 40 | #endif |
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| 41 | { |
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| 42 | int32_t i0,i1,j0; |
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| 43 | u_int32_t i,j; |
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| 44 | EXTRACT_WORDS(i0,i1,x); |
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| 45 | j0 = ((i0>>20)&0x7ff)-0x3ff; |
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| 46 | if(j0<20) { |
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| 47 | if(j0<0) { /* raise inexact if x != 0 */ |
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| 48 | if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
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| 49 | if(i0>=0) {i0=i1=0;} |
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| 50 | else if(((i0&0x7fffffff)|i1)!=0) |
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| 51 | { i0=0xbff00000;i1=0;} |
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| 52 | } |
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| 53 | } else { |
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| 54 | i = (0x000fffff)>>j0; |
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| 55 | if(((i0&i)|i1)==0) return x; /* x is integral */ |
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| 56 | if(huge+x>0.0) { /* raise inexact flag */ |
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| 57 | if(i0<0) i0 += (0x00100000)>>j0; |
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| 58 | i0 &= (~i); i1=0; |
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| 59 | } |
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| 60 | } |
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| 61 | } else if (j0>51) { |
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| 62 | if(j0==0x400) return x+x; /* inf or NaN */ |
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| 63 | else return x; /* x is integral */ |
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| 64 | } else { |
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| 65 | i = ((u_int32_t)(0xffffffff))>>(j0-20); |
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| 66 | if((i1&i)==0) return x; /* x is integral */ |
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| 67 | if(huge+x>0.0) { /* raise inexact flag */ |
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| 68 | if(i0<0) { |
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| 69 | if(j0==20) i0+=1; |
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| 70 | else { |
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| 71 | j = i1+(1<<(52-j0)); |
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| 72 | if(j<i1) i0 +=1 ; /* got a carry */ |
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| 73 | i1=j; |
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| 74 | } |
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| 75 | } |
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| 76 | i1 &= (~i); |
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| 77 | } |
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| 78 | } |
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| 79 | INSERT_WORDS(x,i0,i1); |
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| 80 | return x; |
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| 81 | } |