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1 | ------------------------------------------------------------------------------ |
2 | -- -- | |
3 | -- GNAT LIBRARY COMPONENTS -- | |
4 | -- -- | |
5 | -- S Y S T E M . C R C 3 2 -- | |
6 | -- -- | |
7 | -- B o d y -- | |
8 | -- -- | |
fbf5a39b | 9 | -- Copyright (C) 2001-2002 Free Software Foundation, Inc. -- |
cfac6e9f PO |
10 | -- -- |
11 | -- GNAT is free software; you can redistribute it and/or modify it under -- | |
12 | -- terms of the GNU General Public License as published by the Free Soft- -- | |
13 | -- ware Foundation; either version 2, or (at your option) any later ver- -- | |
14 | -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- | |
15 | -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- | |
16 | -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- | |
17 | -- for more details. You should have received a copy of the GNU General -- | |
18 | -- Public License distributed with GNAT; see file COPYING. If not, write -- | |
19 | -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- | |
20 | -- MA 02111-1307, USA. -- | |
21 | -- -- | |
22 | -- As a special exception, if other files instantiate generics from this -- | |
23 | -- unit, or you link this unit with other files to produce an executable, -- | |
24 | -- this unit does not by itself cause the resulting executable to be -- | |
25 | -- covered by the GNU General Public License. This exception does not -- | |
26 | -- however invalidate any other reasons why the executable file might be -- | |
27 | -- covered by the GNU Public License. -- | |
28 | -- -- | |
fbf5a39b AC |
29 | -- GNAT was originally developed by the GNAT team at New York University. -- |
30 | -- Extensive contributions were provided by Ada Core Technologies Inc. -- | |
cfac6e9f PO |
31 | -- -- |
32 | ------------------------------------------------------------------------------ | |
33 | ||
34 | package body System.CRC32 is | |
35 | ||
36 | Init : constant CRC32 := 16#FFFF_FFFF#; -- Initial value | |
37 | XorOut : constant CRC32 := 16#FFFF_FFFF#; -- To compute final result. | |
38 | ||
39 | -- The following table contains precomputed values for contributions | |
40 | -- from various possible byte values. Doing a table lookup is quicker | |
41 | -- than processing the byte bit by bit. | |
42 | ||
fbf5a39b | 43 | Table : constant array (CRC32 range 0 .. 255) of CRC32 := |
cfac6e9f PO |
44 | (16#0000_0000#, 16#7707_3096#, 16#EE0E_612C#, 16#9909_51BA#, |
45 | 16#076D_C419#, 16#706A_F48F#, 16#E963_A535#, 16#9E64_95A3#, | |
46 | 16#0EDB_8832#, 16#79DC_B8A4#, 16#E0D5_E91E#, 16#97D2_D988#, | |
47 | 16#09B6_4C2B#, 16#7EB1_7CBD#, 16#E7B8_2D07#, 16#90BF_1D91#, | |
48 | 16#1DB7_1064#, 16#6AB0_20F2#, 16#F3B9_7148#, 16#84BE_41DE#, | |
49 | 16#1ADA_D47D#, 16#6DDD_E4EB#, 16#F4D4_B551#, 16#83D3_85C7#, | |
50 | 16#136C_9856#, 16#646B_A8C0#, 16#FD62_F97A#, 16#8A65_C9EC#, | |
51 | 16#1401_5C4F#, 16#6306_6CD9#, 16#FA0F_3D63#, 16#8D08_0DF5#, | |
52 | 16#3B6E_20C8#, 16#4C69_105E#, 16#D560_41E4#, 16#A267_7172#, | |
53 | 16#3C03_E4D1#, 16#4B04_D447#, 16#D20D_85FD#, 16#A50A_B56B#, | |
54 | 16#35B5_A8FA#, 16#42B2_986C#, 16#DBBB_C9D6#, 16#ACBC_F940#, | |
55 | 16#32D8_6CE3#, 16#45DF_5C75#, 16#DCD6_0DCF#, 16#ABD1_3D59#, | |
56 | 16#26D9_30AC#, 16#51DE_003A#, 16#C8D7_5180#, 16#BFD0_6116#, | |
57 | 16#21B4_F4B5#, 16#56B3_C423#, 16#CFBA_9599#, 16#B8BD_A50F#, | |
58 | 16#2802_B89E#, 16#5F05_8808#, 16#C60C_D9B2#, 16#B10B_E924#, | |
59 | 16#2F6F_7C87#, 16#5868_4C11#, 16#C161_1DAB#, 16#B666_2D3D#, | |
60 | 16#76DC_4190#, 16#01DB_7106#, 16#98D2_20BC#, 16#EFD5_102A#, | |
61 | 16#71B1_8589#, 16#06B6_B51F#, 16#9FBF_E4A5#, 16#E8B8_D433#, | |
62 | 16#7807_C9A2#, 16#0F00_F934#, 16#9609_A88E#, 16#E10E_9818#, | |
63 | 16#7F6A_0DBB#, 16#086D_3D2D#, 16#9164_6C97#, 16#E663_5C01#, | |
64 | 16#6B6B_51F4#, 16#1C6C_6162#, 16#8565_30D8#, 16#F262_004E#, | |
65 | 16#6C06_95ED#, 16#1B01_A57B#, 16#8208_F4C1#, 16#F50F_C457#, | |
66 | 16#65B0_D9C6#, 16#12B7_E950#, 16#8BBE_B8EA#, 16#FCB9_887C#, | |
67 | 16#62DD_1DDF#, 16#15DA_2D49#, 16#8CD3_7CF3#, 16#FBD4_4C65#, | |
68 | 16#4DB2_6158#, 16#3AB5_51CE#, 16#A3BC_0074#, 16#D4BB_30E2#, | |
69 | 16#4ADF_A541#, 16#3DD8_95D7#, 16#A4D1_C46D#, 16#D3D6_F4FB#, | |
70 | 16#4369_E96A#, 16#346E_D9FC#, 16#AD67_8846#, 16#DA60_B8D0#, | |
71 | 16#4404_2D73#, 16#3303_1DE5#, 16#AA0A_4C5F#, 16#DD0D_7CC9#, | |
72 | 16#5005_713C#, 16#2702_41AA#, 16#BE0B_1010#, 16#C90C_2086#, | |
73 | 16#5768_B525#, 16#206F_85B3#, 16#B966_D409#, 16#CE61_E49F#, | |
74 | 16#5EDE_F90E#, 16#29D9_C998#, 16#B0D0_9822#, 16#C7D7_A8B4#, | |
75 | 16#59B3_3D17#, 16#2EB4_0D81#, 16#B7BD_5C3B#, 16#C0BA_6CAD#, | |
76 | 16#EDB8_8320#, 16#9ABF_B3B6#, 16#03B6_E20C#, 16#74B1_D29A#, | |
77 | 16#EAD5_4739#, 16#9DD2_77AF#, 16#04DB_2615#, 16#73DC_1683#, | |
78 | 16#E363_0B12#, 16#9464_3B84#, 16#0D6D_6A3E#, 16#7A6A_5AA8#, | |
79 | 16#E40E_CF0B#, 16#9309_FF9D#, 16#0A00_AE27#, 16#7D07_9EB1#, | |
80 | 16#F00F_9344#, 16#8708_A3D2#, 16#1E01_F268#, 16#6906_C2FE#, | |
81 | 16#F762_575D#, 16#8065_67CB#, 16#196C_3671#, 16#6E6B_06E7#, | |
82 | 16#FED4_1B76#, 16#89D3_2BE0#, 16#10DA_7A5A#, 16#67DD_4ACC#, | |
83 | 16#F9B9_DF6F#, 16#8EBE_EFF9#, 16#17B7_BE43#, 16#60B0_8ED5#, | |
84 | 16#D6D6_A3E8#, 16#A1D1_937E#, 16#38D8_C2C4#, 16#4FDF_F252#, | |
85 | 16#D1BB_67F1#, 16#A6BC_5767#, 16#3FB5_06DD#, 16#48B2_364B#, | |
86 | 16#D80D_2BDA#, 16#AF0A_1B4C#, 16#3603_4AF6#, 16#4104_7A60#, | |
87 | 16#DF60_EFC3#, 16#A867_DF55#, 16#316E_8EEF#, 16#4669_BE79#, | |
88 | 16#CB61_B38C#, 16#BC66_831A#, 16#256F_D2A0#, 16#5268_E236#, | |
89 | 16#CC0C_7795#, 16#BB0B_4703#, 16#2202_16B9#, 16#5505_262F#, | |
90 | 16#C5BA_3BBE#, 16#B2BD_0B28#, 16#2BB4_5A92#, 16#5CB3_6A04#, | |
91 | 16#C2D7_FFA7#, 16#B5D0_CF31#, 16#2CD9_9E8B#, 16#5BDE_AE1D#, | |
92 | 16#9B64_C2B0#, 16#EC63_F226#, 16#756A_A39C#, 16#026D_930A#, | |
93 | 16#9C09_06A9#, 16#EB0E_363F#, 16#7207_6785#, 16#0500_5713#, | |
94 | 16#95BF_4A82#, 16#E2B8_7A14#, 16#7BB1_2BAE#, 16#0CB6_1B38#, | |
95 | 16#92D2_8E9B#, 16#E5D5_BE0D#, 16#7CDC_EFB7#, 16#0BDB_DF21#, | |
96 | 16#86D3_D2D4#, 16#F1D4_E242#, 16#68DD_B3F8#, 16#1FDA_836E#, | |
97 | 16#81BE_16CD#, 16#F6B9_265B#, 16#6FB0_77E1#, 16#18B7_4777#, | |
98 | 16#8808_5AE6#, 16#FF0F_6A70#, 16#6606_3BCA#, 16#1101_0B5C#, | |
99 | 16#8F65_9EFF#, 16#F862_AE69#, 16#616B_FFD3#, 16#166C_CF45#, | |
100 | 16#A00A_E278#, 16#D70D_D2EE#, 16#4E04_8354#, 16#3903_B3C2#, | |
101 | 16#A767_2661#, 16#D060_16F7#, 16#4969_474D#, 16#3E6E_77DB#, | |
102 | 16#AED1_6A4A#, 16#D9D6_5ADC#, 16#40DF_0B66#, 16#37D8_3BF0#, | |
103 | 16#A9BC_AE53#, 16#DEBB_9EC5#, 16#47B2_CF7F#, 16#30B5_FFE9#, | |
104 | 16#BDBD_F21C#, 16#CABA_C28A#, 16#53B3_9330#, 16#24B4_A3A6#, | |
105 | 16#BAD0_3605#, 16#CDD7_0693#, 16#54DE_5729#, 16#23D9_67BF#, | |
106 | 16#B366_7A2E#, 16#C461_4AB8#, 16#5D68_1B02#, 16#2A6F_2B94#, | |
107 | 16#B40B_BE37#, 16#C30C_8EA1#, 16#5A05_DF1B#, 16#2D02_EF8D#); | |
108 | ||
109 | --------------- | |
110 | -- Get_Value -- | |
111 | --------------- | |
112 | ||
113 | function Get_Value (C : CRC32) return Interfaces.Unsigned_32 is | |
114 | begin | |
115 | return Interfaces.Unsigned_32 (C xor XorOut); | |
116 | end Get_Value; | |
117 | ||
118 | ---------------- | |
119 | -- Initialize -- | |
120 | ---------------- | |
121 | ||
122 | procedure Initialize (C : out CRC32) is | |
123 | begin | |
124 | C := Init; | |
125 | end Initialize; | |
126 | ||
127 | ------------ | |
128 | -- Update -- | |
129 | ------------ | |
130 | ||
131 | procedure Update (C : in out CRC32; Value : Character) is | |
132 | V : constant CRC32 := CRC32 (Character'Pos (Value)); | |
133 | ||
134 | begin | |
135 | C := Shift_Right (C, 8) xor Table (V xor (C and 16#0000_00FF#)); | |
136 | end Update; | |
137 | ||
138 | end System.CRC32; |