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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY COMPONENTS --
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4 -- --
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5 -- S Y S T E M . C O M P A R E _ A R R A Y _ U N S I G N E D _ 8 --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 2002-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 pragma Compiler_Unit_Warning;
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33
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34 with System.Address_Operations; use System.Address_Operations;
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35
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36 with Ada.Unchecked_Conversion;
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37
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38 package body System.Compare_Array_Unsigned_8 is
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39
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40 type Word is mod 2 ** 32;
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41 -- Used to process operands by words
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42
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43 type Big_Words is array (Natural) of Word;
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44 type Big_Words_Ptr is access Big_Words;
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45 for Big_Words_Ptr'Storage_Size use 0;
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46 -- Array type used to access by words
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47
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48 type Byte is mod 2 ** 8;
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49 -- Used to process operands by bytes
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50
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51 type Big_Bytes is array (Natural) of Byte;
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52 type Big_Bytes_Ptr is access Big_Bytes;
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53 for Big_Bytes_Ptr'Storage_Size use 0;
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54 -- Array type used to access by bytes
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55
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56 function To_Big_Words is new
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57 Ada.Unchecked_Conversion (System.Address, Big_Words_Ptr);
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58
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59 function To_Big_Bytes is new
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60 Ada.Unchecked_Conversion (System.Address, Big_Bytes_Ptr);
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61
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62 ----------------------
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63 -- Compare_Array_U8 --
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64 ----------------------
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65
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66 function Compare_Array_U8
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67 (Left : System.Address;
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68 Right : System.Address;
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69 Left_Len : Natural;
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70 Right_Len : Natural) return Integer
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71 is
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72 Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
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73
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74 begin
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75 -- If operands are non-aligned, or length is too short, go by bytes
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76
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77 if (ModA (OrA (Left, Right), 4) /= 0) or else Compare_Len < 4 then
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78 return Compare_Array_U8_Unaligned (Left, Right, Left_Len, Right_Len);
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79 end if;
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80
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81 -- Here we can go by words
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82
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83 declare
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84 LeftP : constant Big_Words_Ptr :=
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85 To_Big_Words (Left);
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86 RightP : constant Big_Words_Ptr :=
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87 To_Big_Words (Right);
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88 Words_To_Compare : constant Natural := Compare_Len / 4;
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89 Bytes_Compared_As_Words : constant Natural := Words_To_Compare * 4;
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90
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91 begin
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92 for J in 0 .. Words_To_Compare - 1 loop
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93 if LeftP (J) /= RightP (J) then
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94 return Compare_Array_U8_Unaligned
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95 (AddA (Left, Address (4 * J)),
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96 AddA (Right, Address (4 * J)),
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97 4, 4);
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98 end if;
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99 end loop;
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100
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101 return Compare_Array_U8_Unaligned
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102 (AddA (Left, Address (Bytes_Compared_As_Words)),
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103 AddA (Right, Address (Bytes_Compared_As_Words)),
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104 Left_Len - Bytes_Compared_As_Words,
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105 Right_Len - Bytes_Compared_As_Words);
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106 end;
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107 end Compare_Array_U8;
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108
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109 --------------------------------
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110 -- Compare_Array_U8_Unaligned --
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111 --------------------------------
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112
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113 function Compare_Array_U8_Unaligned
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114 (Left : System.Address;
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115 Right : System.Address;
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116 Left_Len : Natural;
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117 Right_Len : Natural) return Integer
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118 is
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119 Compare_Len : constant Natural := Natural'Min (Left_Len, Right_Len);
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120
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121 LeftP : constant Big_Bytes_Ptr := To_Big_Bytes (Left);
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122 RightP : constant Big_Bytes_Ptr := To_Big_Bytes (Right);
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123
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124 begin
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125 for J in 0 .. Compare_Len - 1 loop
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126 if LeftP (J) /= RightP (J) then
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127 if LeftP (J) > RightP (J) then
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128 return +1;
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129 else
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130 return -1;
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131 end if;
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132 end if;
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133 end loop;
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134
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135 if Left_Len = Right_Len then
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136 return 0;
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137 elsif Left_Len > Right_Len then
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138 return +1;
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139 else
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140 return -1;
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141 end if;
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142 end Compare_Array_U8_Unaligned;
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143
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144 end System.Compare_Array_Unsigned_8;
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