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//
//
// The Nimrod Compiler
// (c) Copyright 2008 Andreas Rumpf
//
// See the file "copying.txt", included in this
// distribution, for details about the copyright.
//
unit crc;
interface
{$include 'config.inc'}
uses
nsystem, strutils;
type
TCrc32 = int32;
const
InitCrc32 = TCrc32($ffffffff);
function updateCrc32(val: Byte; crc: TCrc32): TCrc32; overload;
function updateCrc32(val: Char; crc: TCrc32): TCrc32; overload;
function crcFromBuf(buf: Pointer; len: int): TCrc32;
function strCrc32(const s: string): TCrc32;
function crcFromFile(const filename: string): TCrc32;
implementation
{@ignore}
{$ifopt Q+} { we need Q- here! }
{$define Q_on}
{$Q-}
{$endif}
{$ifopt R+}
{$define R_on}
{$R-}
{$endif}
{@emit}
{@ignore}
type
TCRC_TabEntry = TCrc32;
{@emit
type
TCRC_TabEntry = int
}
const
crc32table: array [0..255] of TCRC_TabEntry = (
0, 1996959894, -301047508, -1727442502,
124634137, 1886057615, -379345611, -1637575261,
249268274, 2044508324, -522852066, -1747789432,
162941995, 2125561021, -407360249, -1866523247,
498536548, 1789927666, -205950648, -2067906082,
450548861, 1843258603, -187386543, -2083289657,
325883990, 1684777152, -43845254, -1973040660,
335633487, 1661365465, -99664541, -1928851979,
997073096, 1281953886, -715111964, -1570279054,
1006888145, 1258607687, -770865667, -1526024853,
901097722, 1119000684, -608450090, -1396901568,
853044451, 1172266101, -589951537, -1412350631,
651767980, 1373503546, -925412992, -1076862698,
565507253, 1454621731, -809855591, -1195530993,
671266974, 1594198024, -972236366, -1324619484,
795835527, 1483230225, -1050600021, -1234817731,
1994146192, 31158534, -1731059524, -271249366,
1907459465, 112637215, -1614814043, -390540237,
2013776290, 251722036, -1777751922, -519137256,
2137656763, 141376813, -1855689577, -429695999,
1802195444, 476864866, -2056965928, -228458418,
1812370925, 453092731, -2113342271, -183516073,
1706088902, 314042704, -1950435094, -54949764,
1658658271, 366619977, -1932296973, -69972891,
1303535960, 984961486, -1547960204, -725929758,
1256170817, 1037604311, -1529756563, -740887301,
1131014506, 879679996, -1385723834, -631195440,
1141124467, 855842277, -1442165665, -586318647,
1342533948, 654459306, -1106571248, -921952122,
1466479909, 544179635, -1184443383, -832445281,
1591671054, 702138776, -1328506846, -942167884,
1504918807, 783551873, -1212326853, -1061524307,
-306674912, -1698712650, 62317068, 1957810842,
-355121351, -1647151185, 81470997, 1943803523,
-480048366, -1805370492, 225274430, 2053790376,
-468791541, -1828061283, 167816743, 2097651377,
-267414716, -2029476910, 503444072, 1762050814,
-144550051, -2140837941, 426522225, 1852507879,
-19653770, -1982649376, 282753626, 1742555852,
-105259153, -1900089351, 397917763, 1622183637,
-690576408, -1580100738, 953729732, 1340076626,
-776247311, -1497606297, 1068828381, 1219638859,
-670225446, -1358292148, 906185462, 1090812512,
-547295293, -1469587627, 829329135, 1181335161,
-882789492, -1134132454, 628085408, 1382605366,
-871598187, -1156888829, 570562233, 1426400815,
-977650754, -1296233688, 733239954, 1555261956,
-1026031705, -1244606671, 752459403, 1541320221,
-1687895376, -328994266, 1969922972, 40735498,
-1677130071, -351390145, 1913087877, 83908371,
-1782625662, -491226604, 2075208622, 213261112,
-1831694693, -438977011, 2094854071, 198958881,
-2032938284, -237706686, 1759359992, 534414190,
-2118248755, -155638181, 1873836001, 414664567,
-2012718362, -15766928, 1711684554, 285281116,
-1889165569, -127750551, 1634467795, 376229701,
-1609899400, -686959890, 1308918612, 956543938,
-1486412191, -799009033, 1231636301, 1047427035,
-1362007478, -640263460, 1088359270, 936918000,
-1447252397, -558129467, 1202900863, 817233897,
-1111625188, -893730166, 1404277552, 615818150,
-1160759803, -841546093, 1423857449, 601450431,
-1285129682, -1000256840, 1567103746, 711928724,
-1274298825, -1022587231, 1510334235, 755167117
);
function updateCrc32(val: Byte; crc: TCrc32): TCrc32; overload;
begin
result := crc32Table[(int(crc) xor val) and $ff] xor (crc shr 8);
end;
function updateCrc32(val: Char; crc: TCrc32): TCrc32; overload;
begin
result := updateCrc32(ord(val), crc);
end;
function strCrc32(const s: string): TCrc32;
var
i: int;
begin
result := InitCrc32;
for i := strStart to length(s)+StrStart-1 do
result := updateCrc32(s[i], result)
end;
type
TByteArray = array [0..10000000] of Byte;
PByteArray = ^TByteArray;
function crcFromBuf(buf: Pointer; len: int): TCrc32;
var
p: PByteArray;
i: int;
begin
p := {@cast}PByteArray(buf);
result := InitCrc32;
for i := 0 to len-1 do result := updateCrc32(p[i], result)
end;
function crcFromFile(const filename: string): TCrc32;
const
bufSize = 8 * 1024;
var
bin: TBinaryFile;
buf: Pointer;
readBytes, i: int;
p: PByteArray;
begin
result := InitCrc32;
if not openFile(bin, filename) then exit; // not equal if file does not exist
buf := alloc(BufSize);
p := {@cast}PByteArray(buf);
while true do begin
readBytes := readBuffer(bin, buf, bufSize);
for i := 0 to readBytes-1 do result := updateCrc32(p[i], result);
if readBytes <> bufSize then break;
end;
dealloc(buf);
CloseFile(bin);
end;
{@ignore}
{$ifdef Q_on}
{$undef Q_on}
{$Q+}
{$endif}
{$ifdef R_on}
{$undef R_on}
{$R+}
{$endif}
{@emit}
end.
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