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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- S Y S T E M . A D D R E S S _ O P E R A T I O N S --
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6 -- --
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7 -- S p e c --
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8 -- --
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9 -- Copyright (C) 2004-2017, Free Software Foundation, Inc. --
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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 -- This package provides arithmetic and logical operations on type Address.
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33 -- It is intended for use by other packages in the System hierarchy. For
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34 -- applications requiring this capability, see System.Storage_Elements or
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35 -- the operations introduced in System.Aux_DEC;
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36
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37 -- The reason we need this package is that arithmetic operations may not
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38 -- be available in the case where type Address is non-private and the
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39 -- operations have been made abstract in the spec of System (to avoid
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40 -- inappropriate use by applications programs). In addition, the logical
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41 -- operations may not be available if type Address is a signed integer.
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42
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43 pragma Compiler_Unit_Warning;
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44
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45 package System.Address_Operations is
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46 pragma Pure;
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47
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48 -- The semantics of the arithmetic operations are those that apply to
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49 -- a modular type with the same length as Address, i.e. they provide
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50 -- twos complement wrap around arithmetic treating the address value
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51 -- as an unsigned value, with no overflow checking.
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52
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53 -- Note that we do not use the infix names for these operations to
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54 -- avoid problems with ambiguities coming from declarations in package
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55 -- Standard (which may or may not be visible depending on the exact
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56 -- form of the declaration of type System.Address).
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57
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58 -- For addition, subtraction, and multiplication, the effect of overflow
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59 -- is 2's complement wrapping (as though the type Address were unsigned).
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60
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61 -- For division and modulus operations, the caller is responsible for
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62 -- ensuring that the Right argument is non-zero, and the effect of the
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63 -- call is not specified if a zero argument is passed.
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64
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65 function AddA (Left, Right : Address) return Address;
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66 function SubA (Left, Right : Address) return Address;
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67 function MulA (Left, Right : Address) return Address;
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68 function DivA (Left, Right : Address) return Address;
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69 function ModA (Left, Right : Address) return Address;
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70
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71 -- The semantics of the logical operations are those that apply to
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72 -- a modular type with the same length as Address, i.e. they provide
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73 -- bit-wise operations on all bits of the value (including the sign
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74 -- bit if Address is a signed integer type).
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75
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76 function AndA (Left, Right : Address) return Address;
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77 function OrA (Left, Right : Address) return Address;
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78
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79 pragma Inline_Always (AddA);
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80 pragma Inline_Always (SubA);
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81 pragma Inline_Always (MulA);
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82 pragma Inline_Always (DivA);
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83 pragma Inline_Always (ModA);
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84 pragma Inline_Always (AndA);
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85 pragma Inline_Always (OrA);
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86
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87 end System.Address_Operations;
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