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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- S Y S T E M . B I T _ O P 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) 1992-2018, 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 -- Operations on packed bit strings
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33
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34 pragma Compiler_Unit_Warning;
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35
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36 with System;
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37
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38 package System.Bit_Ops is
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39
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40 -- Note: in all the following routines, the System.Address parameters
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41 -- represent the address of the first byte of an array used to represent
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42 -- a packed array (of type System.Unsigned_Types.Packed_Bytes{1,2,4})
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43 -- The length in bits is passed as a separate parameter. Note that all
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44 -- addresses must be of byte aligned arrays.
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45
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46 procedure Bit_And
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47 (Left : System.Address;
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48 Llen : Natural;
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49 Right : System.Address;
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50 Rlen : Natural;
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51 Result : System.Address);
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52 -- Bitwise "and" of given bit string with result being placed in Result.
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53 -- The and operation is allowed to destroy unused bits in the last byte,
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54 -- i.e. to leave them set in an undefined manner. Note that Left, Right
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55 -- and Result always have the same length in bits (Len).
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56
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57 function Bit_Eq
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58 (Left : System.Address;
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59 Llen : Natural;
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60 Right : System.Address;
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61 Rlen : Natural) return Boolean;
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62 -- Left and Right are the addresses of two bit packed arrays with Llen
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63 -- and Rlen being the respective length in bits. The routine compares the
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64 -- two bit strings for equality, being careful not to include the unused
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65 -- bits in the final byte. Note that the result is always False if Rlen
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66 -- is not equal to Llen.
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67
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68 procedure Bit_Not
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69 (Opnd : System.Address;
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70 Len : Natural;
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71 Result : System.Address);
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72 -- Bitwise "not" of given bit string with result being placed in Result.
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73 -- The not operation is allowed to destroy unused bits in the last byte,
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74 -- i.e. to leave them set in an undefined manner. Note that Result and
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75 -- Opnd always have the same length in bits (Len).
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76
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77 procedure Bit_Or
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78 (Left : System.Address;
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79 Llen : Natural;
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80 Right : System.Address;
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81 Rlen : Natural;
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82 Result : System.Address);
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83 -- Bitwise "or" of given bit string with result being placed in Result.
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84 -- The or operation is allowed to destroy unused bits in the last byte,
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85 -- i.e. to leave them set in an undefined manner. Note that Left, Right
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86 -- and Result always have the same length in bits (Len).
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87
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88 procedure Bit_Xor
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89 (Left : System.Address;
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90 Llen : Natural;
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91 Right : System.Address;
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92 Rlen : Natural;
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93 Result : System.Address);
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94 -- Bitwise "xor" of given bit string with result being placed in Result.
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95 -- The xor operation is allowed to destroy unused bits in the last byte,
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96 -- i.e. to leave them set in an undefined manner. Note that Left, Right
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97 -- and Result always have the same length in bits (Len).
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98
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99 end System.Bit_Ops;
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