lib/builtins/comparesf2.c

   1 //===-- lib/comparesf2.c - Single-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-fp_t comparison routines:
  11 //
  12 //   __eqsf2   __gesf2   __unordsf2
  13 //   __lesf2   __gtsf2
  14 //   __ltsf2
  15 //   __nesf2
  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 //   __lesf2(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 //   __gesf2(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 //   __unordsf2(a,b) returns 0 if both a and b are numbers
  33 //                           1 if either a or b is NaN
  34 //
  35 // Note that __lesf2( ) and __gesf2( ) are identical except in their handling of
  36 // NaN values.
  37 //
  38 //===----------------------------------------------------------------------===//
  39
  40 #define SINGLE_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 COMPILER_RT_ABI enum LE_RESULT
  51 __lesf2(fp_t a, fp_t b) {
  52
  53     const srep_t aInt = toRep(a);
  54     const srep_t bInt = toRep(b);
  55     const rep_t aAbs = aInt & absMask;
  56     const rep_t bAbs = bInt & absMask;
  57
  58     // If either a or b is NaN, they are unordered.
  59     if (aAbs > infRep || bAbs > infRep) return LE_UNORDERED;
  60
  61     // If a and b are both zeros, they are equal.
  62     if ((aAbs | bAbs) == 0) return LE_EQUAL;
  63
  64     // If at least one of a and b is positive, we get the same result comparing
  65     // a and b as signed integers as we would with a fp_ting-point compare.
  66     if ((aInt & bInt) >= 0) {
  67         if (aInt < bInt) return LE_LESS;
  68         else if (aInt == bInt) return LE_EQUAL;
  69         else return LE_GREATER;
  70     }
  71
  72     // Otherwise, both are negative, so we need to flip the sense of the
  73     // comparison to get the correct result.  (This assumes a twos- or ones-
  74     // complement integer representation; if integers are represented in a
  75     // sign-magnitude representation, then this flip is incorrect).
  76     else {
  77         if (aInt > bInt) return LE_LESS;
  78         else if (aInt == bInt) return LE_EQUAL;
  79         else return LE_GREATER;
  80     }
  81 }
  82
  83 enum GE_RESULT {
  84     GE_LESS      = -1,
  85     GE_EQUAL     =  0,
  86     GE_GREATER   =  1,
  87     GE_UNORDERED = -1   // Note: different from LE_UNORDERED
  88 };
  89
  90 COMPILER_RT_ABI enum GE_RESULT
  91 __gesf2(fp_t a, fp_t b) {
  92
  93     const srep_t aInt = toRep(a);
  94     const srep_t bInt = toRep(b);
  95     const rep_t aAbs = aInt & absMask;
  96     const rep_t bAbs = bInt & absMask;
  97
  98     if (aAbs > infRep || bAbs > infRep) return GE_UNORDERED;
  99     if ((aAbs | bAbs) == 0) return GE_EQUAL;
 100     if ((aInt & bInt) >= 0) {
 101         if (aInt < bInt) return GE_LESS;
 102         else if (aInt == bInt) return GE_EQUAL;
 103         else return GE_GREATER;
 104     } else {
 105         if (aInt > bInt) return GE_LESS;
 106         else if (aInt == bInt) return GE_EQUAL;
 107         else return GE_GREATER;
 108     }
 109 }
 110
 111 ARM_EABI_FNALIAS(fcmpun, unordsf2)
 112
 113 COMPILER_RT_ABI int
 114 __unordsf2(fp_t a, fp_t b) {
 115     const rep_t aAbs = toRep(a) & absMask;
 116     const rep_t bAbs = toRep(b) & absMask;
 117     return aAbs > infRep || bAbs > infRep;
 118 }
 119
 120 // The following are alternative names for the preceding routines.
 121
 122 COMPILER_RT_ABI enum LE_RESULT
 123 __eqsf2(fp_t a, fp_t b) {
 124     return __lesf2(a, b);
 125 }
 126
 127 COMPILER_RT_ABI enum LE_RESULT
 128 __ltsf2(fp_t a, fp_t b) {
 129     return __lesf2(a, b);
 130 }
 131
 132 COMPILER_RT_ABI enum LE_RESULT
 133 __nesf2(fp_t a, fp_t b) {
 134     return __lesf2(a, b);
 135 }
 136
 137 COMPILER_RT_ABI enum GE_RESULT
 138 __gtsf2(fp_t a, fp_t b) {
 139     return __gesf2(a, b);
 140 }