1 /* $OpenBSD: dfcmp.c,v 1.6 2002/09/20 19:26:59 mickey Exp $ */ 2 /* 3 (c) Copyright 1986 HEWLETT-PACKARD COMPANY 4 To anyone who acknowledges that this file is provided "AS IS" 5 without any express or implied warranty: 6 permission to use, copy, modify, and distribute this file 7 for any purpose is hereby granted without fee, provided that 8 the above copyright notice and this notice appears in all 9 copies, and that the name of Hewlett-Packard Company not be 10 used in advertising or publicity pertaining to distribution 11 of the software without specific, written prior permission. 12 Hewlett-Packard Company makes no representations about the 13 suitability of this software for any purpose. 14 */ 15 /* @(#)dfcmp.c: Revision: 1.7.88.2 Date: 93/12/08 13:26:38 */ 16 17 #include "float.h" 18 #include "dbl_float.h" 19 20 /* 21 * dbl_cmp: compare two values 22 */ 23 int 24 dbl_fcmp(leftptr, rightptr, cond, status) 25 dbl_floating_point *leftptr, *rightptr; 26 unsigned int cond; /* The predicate to be tested */ 27 unsigned int *status; 28 { 29 register unsigned int leftp1, leftp2, rightp1, rightp2; 30 register int xorresult; 31 32 /* Create local copies of the numbers */ 33 Dbl_copyfromptr(leftptr,leftp1,leftp2); 34 Dbl_copyfromptr(rightptr,rightp1,rightp2); 35 /* 36 * Test for NaN 37 */ 38 if( (Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT) 39 || (Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) ) 40 { 41 /* Check if a NaN is involved. Signal an invalid exception when 42 * comparing a signaling NaN or when comparing quiet NaNs and the 43 * low bit of the condition is set */ 44 if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT) 45 && Dbl_isnotzero_mantissa(leftp1,leftp2) 46 && (Exception(cond) || Dbl_isone_signaling(leftp1))) 47 || 48 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) 49 && Dbl_isnotzero_mantissa(rightp1,rightp2) 50 && (Exception(cond) || Dbl_isone_signaling(rightp1))) ) 51 { 52 if( Is_invalidtrap_enabled() ) { 53 Set_status_cbit(Unordered(cond)); 54 return(INVALIDEXCEPTION); 55 } 56 else Set_invalidflag(); 57 Set_status_cbit(Unordered(cond)); 58 return(NOEXCEPTION); 59 } 60 /* All the exceptional conditions are handled, now special case 61 NaN compares */ 62 else if( ((Dbl_exponent(leftp1) == DBL_INFINITY_EXPONENT) 63 && Dbl_isnotzero_mantissa(leftp1,leftp2)) 64 || 65 ((Dbl_exponent(rightp1) == DBL_INFINITY_EXPONENT) 66 && Dbl_isnotzero_mantissa(rightp1,rightp2)) ) 67 { 68 /* NaNs always compare unordered. */ 69 Set_status_cbit(Unordered(cond)); 70 return(NOEXCEPTION); 71 } 72 /* infinities will drop down to the normal compare mechanisms */ 73 } 74 /* First compare for unequal signs => less or greater or 75 * special equal case */ 76 Dbl_xortointp1(leftp1,rightp1,xorresult); 77 if( xorresult < 0 ) 78 { 79 /* left negative => less, left positive => greater. 80 * equal is possible if both operands are zeros. */ 81 if( Dbl_iszero_exponentmantissa(leftp1,leftp2) 82 && Dbl_iszero_exponentmantissa(rightp1,rightp2) ) 83 { 84 Set_status_cbit(Equal(cond)); 85 } 86 else if( Dbl_isone_sign(leftp1) ) 87 { 88 Set_status_cbit(Lessthan(cond)); 89 } 90 else 91 { 92 Set_status_cbit(Greaterthan(cond)); 93 } 94 } 95 /* Signs are the same. Treat negative numbers separately 96 * from the positives because of the reversed sense. */ 97 else if(Dbl_isequal(leftp1,leftp2,rightp1,rightp2)) 98 { 99 Set_status_cbit(Equal(cond)); 100 } 101 else if( Dbl_iszero_sign(leftp1) ) 102 { 103 /* Positive compare */ 104 if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) ) 105 { 106 Set_status_cbit(Lessthan(cond)); 107 } 108 else if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) ) 109 { 110 Set_status_cbit(Greaterthan(cond)); 111 } 112 else 113 { 114 /* Equal first parts. Now we must use unsigned compares to 115 * resolve the two possibilities. */ 116 if( Dbl_allp2(leftp2) < Dbl_allp2(rightp2) ) 117 { 118 Set_status_cbit(Lessthan(cond)); 119 } 120 else 121 { 122 Set_status_cbit(Greaterthan(cond)); 123 } 124 } 125 } 126 else 127 { 128 /* Negative compare. Signed or unsigned compares 129 * both work the same. That distinction is only 130 * important when the sign bits differ. */ 131 if( Dbl_allp1(leftp1) > Dbl_allp1(rightp1) ) 132 { 133 Set_status_cbit(Lessthan(cond)); 134 } 135 else if( Dbl_allp1(leftp1) < Dbl_allp1(rightp1) ) 136 { 137 Set_status_cbit(Greaterthan(cond)); 138 } 139 else 140 { 141 /* Equal first parts. Now we must use unsigned compares to 142 * resolve the two possibilities. */ 143 if( Dbl_allp2(leftp2) > Dbl_allp2(rightp2) ) 144 { 145 Set_status_cbit(Lessthan(cond)); 146 } 147 else 148 { 149 Set_status_cbit(Greaterthan(cond)); 150 } 151 } 152 } 153 return(NOEXCEPTION); 154 } 155