lib/comparedf2.c

   1 //===-- lib/comparedf2.c - Double-precision comparisons -----------*- C -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // // This file implements the following soft-float comparison routines:
  11 //
  12 //   __eqdf2   __gedf2   __unorddf2
  13 //   __ledf2   __gtdf2
  14 //   __ltdf2
  15 //   __nedf2
  16 //
  17 // The semantics of the routines grouped in each column are identical, so there
  18 // is a single implementation for each, and wrappers to provide the other names.
  19 //
  20 // The main routines behave as follows:
  21 //
  22 //   __ledf2(a,b) returns -1 if a < b
  23 //                         0 if a == b
  24 //                         1 if a > b
  25 //                         1 if either a or b is NaN
  26 //
  27 //   __gedf2(a,b) returns -1 if a < b
  28 //                         0 if a == b
  29 //                         1 if a > b
  30 //                        -1 if either a or b is NaN
  31 //
  32 //   __unorddf2(a,b) returns 0 if both a and b are numbers
  33 //                           1 if either a or b is NaN
  34 //
  35 // Note that __ledf2( ) and __gedf2( ) are identical except in their handling of
  36 // NaN values.
  37 //
  38 //===----------------------------------------------------------------------===//
  39
  40 #define DOUBLE_PRECISION
  41 #include "fp_lib.h"
  42
  43 enum LE_RESULT {
  44     LE_LESS      = -1,
  45     LE_EQUAL     =  0,
  46     LE_GREATER   =  1,
  47     LE_UNORDERED =  1
  48 };
  49
  50 enum LE_RESULT __ledf2(fp_t a, fp_t b) {
  51
  52     const srep_t aInt = toRep(a);
  53     const srep_t bInt = toRep(b);
  54     const rep_t aAbs = aInt & absMask;
  55     const rep_t bAbs = bInt & absMask;
  56
  57     // If either a or b is NaN, they are unordered.
  58     if (aAbs > infRep || bAbs > infRep) return LE_UNORDERED;
  59
  60     // If a and b are both zeros, they are equal.
  61     if ((aAbs | bAbs) == 0) return LE_EQUAL;
  62
  63     // If at least one of a and b is positive, we get the same result comparing
  64     // a and b as signed integers as we would with a floating-point compare.
  65     if ((aInt & bInt) >= 0) {
  66         if (aInt < bInt) return LE_LESS;
  67         else if (aInt == bInt) return LE_EQUAL;
  68         else return LE_GREATER;
  69     }
  70
  71     // Otherwise, both are negative, so we need to flip the sense of the
  72     // comparison to get the correct result.  (This assumes a twos- or ones-
  73     // complement integer representation; if integers are represented in a
  74     // sign-magnitude representation, then this flip is incorrect).
  75     else {
  76         if (aInt > bInt) return LE_LESS;
  77         else if (aInt == bInt) return LE_EQUAL;
  78         else return LE_GREATER;
  79     }
  80 }
  81
  82 enum GE_RESULT {
  83     GE_LESS      = -1,
  84     GE_EQUAL     =  0,
  85     GE_GREATER   =  1,
  86     GE_UNORDERED = -1   // Note: different from LE_UNORDERED
  87 };
  88
  89 enum GE_RESULT __gedf2(fp_t a, fp_t b) {
  90
  91     const srep_t aInt = toRep(a);
  92     const srep_t bInt = toRep(b);
  93     const rep_t aAbs = aInt & absMask;
  94     const rep_t bAbs = bInt & absMask;
  95
  96     if (aAbs > infRep || bAbs > infRep) return GE_UNORDERED;
  97     if ((aAbs | bAbs) == 0) return GE_EQUAL;
  98     if ((aInt & bInt) >= 0) {
  99         if (aInt < bInt) return GE_LESS;
 100         else if (aInt == bInt) return GE_EQUAL;
 101         else return GE_GREATER;
 102     } else {
 103         if (aInt > bInt) return GE_LESS;
 104         else if (aInt == bInt) return GE_EQUAL;
 105         else return GE_GREATER;
 106     }
 107 }
 108
 109 ARM_EABI_FNALIAS(dcmpun, unorddf2)
 110
 111 int __unorddf2(fp_t a, fp_t b) {
 112     const rep_t aAbs = toRep(a) & absMask;
 113     const rep_t bAbs = toRep(b) & absMask;
 114     return aAbs > infRep || bAbs > infRep;
 115 }
 116
 117 // The following are alternative names for the preceeding routines.
 118
 119 enum LE_RESULT __eqdf2(fp_t a, fp_t b) {
 120     return __ledf2(a, b);
 121 }
 122
 123 enum LE_RESULT __ltdf2(fp_t a, fp_t b) {
 124     return __ledf2(a, b);
 125 }
 126
 127 enum LE_RESULT __nedf2(fp_t a, fp_t b) {
 128     return __ledf2(a, b);
 129 }
 130
 131 enum GE_RESULT __gtdf2(fp_t a, fp_t b) {
 132     return __gedf2(a, b);
 133 }
 134