// This may look like C code, but it is really -*- C++ -*-
// ------------------------------------------------------------------
// The Goldware Library
// Copyright (C) 1990-1999 Odinn Sorensen
// ------------------------------------------------------------------
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this program; if not, write to the Free
// Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
// MA 02111-1307, USA
// ------------------------------------------------------------------
// $Id$
// ------------------------------------------------------------------
// CRC-16, CRC-32 and Hashing
// ------------------------------------------------------------------
#include <gcrcall.h>
// ------------------------------------------------------------------
// Quickie table for CRC-32 calculations
//
// Copyright (C) 1986 Gary S. Brown. You may use this table as
// desired without restriction.
//
// First, the polynomial itself and its table of feedback terms. The
// polynomial is
//
// X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
//
// Note that we take it "backwards" and put the highest-order term in
// the lowest-order bit. The X^32 term is "implied"; the LSB is the
// X^31 term, etc. The X^0 term (usually shown as "+1") results in
// the MSB being 1.
//
// Note that the usual hardware shift register implementation, which
// is what we're using (we're merely optimizing it by doing eight-bit
// chunks at a time) shifts bits into the lowest-order term. In our
// implementation, that means shifting towards the right. Why do we
// do it this way? Because the calculated CRC must be transmitted in
// order from highest-order term to lowest-order term. UARTs transmit
// characters in order from LSB to MSB. By storing the CRC this way,
// we hand it to the UART in the order low-byte to high-byte; the
// UART sends each low-bit to hight-bit; and the result is trans-
// mission bit by bit from highest- to lowest-order term without re-
// quiring any bit shuffling on our part. Reception works similarly.
//
// The feedback terms table consists of 256, 32-bit entries. Notes:
//
// 1. The table can be generated at runtime if desired; code to do
// so is shown later [ED: Nope]. It might not be obvious, but the
// feedback terms simply represent the results of eight shift/xor
// operations for all combinations of data and CRC register
// values.
//
// 2. The CRC accumulation logic is the same for all CRC polyno-
// mials, be they sixteen or thirty-two bits wide. You simply
// choose the appropriate table. Alternatively, because the table
// can be generated at runtime, you can start by generating the
// table for the polynomial in question and use exactly the same
// "updcrc", if your application needn't simultaneously handle
// two CRC polynomials. (Note, however, that XMODEM is strange.)
//
// 3. For 16-bit CRCs, the table entries need be only 16 bits wide;
// of course, 32-bit entries work OK if the high 16 bits are
// zero.
//
// 4. The values must be right-shifted by eight bits by the "updcrc"
// logic; the shift must be unsigned (bring in zeroes). On some
// hardware you could probably optimize the shift in assembler by
// using byte-swap instructions. [ED: But we let the compiler
// worry about the details in this implementation...]
//
// 5. The CRC-32 polynomial value is: 0xEDB88320.
//
// ------------------------------------------------------------------
dword __crc32_table[256] = {
0x00000000L, 0x77073096L, 0xEE0E612CL, 0x990951BAL,
0x076DC419L, 0x706AF48FL, 0xE963A535L, 0x9E6495A3L,
0x0EDB8832L, 0x79DCB8A4L, 0xE0D5E91EL, 0x97D2D988L,
0x09B64C2BL, 0x7EB17CBDL, 0xE7B82D07L, 0x90BF1D91L,
0x1DB71064L, 0x6AB020F2L, 0xF3B97148L, 0x84BE41DEL,
0x1ADAD47DL, 0x6DDDE4EBL, 0xF4D4B551L, 0x83D385C7L,
0x136C9856L, 0x646BA8C0L, 0xFD62F97AL, 0x8A65C9ECL,
0x14015C4FL, 0x63066CD9L, 0xFA0F3D63L, 0x8D080DF5L,
0x3B6E20C8L, 0x4C69105EL, 0xD56041E4L, 0xA2677172L,
0x3C03E4D1L, 0x4B04D447L, 0xD20D85FDL, 0xA50AB56BL,
0x35B5A8FAL, 0x42B2986CL, 0xDBBBC9D6L, 0xACBCF940L,
0x32D86CE3L, 0x45DF5C75L, 0xDCD60DCFL, 0xABD13D59L,
0x26D930ACL, 0x51DE003AL, 0xC8D75180L, 0xBFD06116L,
0x21B4F4B5L, 0x56B3C423L, 0xCFBA9599L, 0xB8BDA50FL,
0x2802B89EL, 0x5F058808L, 0xC60CD9B2L, 0xB10BE924L,
0x2F6F7C87L, 0x58684C11L, 0xC1611DABL, 0xB6662D3DL,
0x76DC4190L, 0x01DB7106L, 0x98D220BCL, 0xEFD5102AL,
0x71B18589L, 0x06B6B51FL, 0x9FBFE4A5L, 0xE8B8D433L,
0x7807C9A2L, 0x0F00F934L, 0x9609A88EL, 0xE10E9818L,
0x7F6A0DBBL, 0x086D3D2DL, 0x91646C97L, 0xE6635C01L,
0x6B6B51F4L, 0x1C6C6162L, 0x856530D8L, 0xF262004EL,
0x6C0695EDL, 0x1B01A57BL, 0x8208F4C1L, 0xF50FC457L,
0x65B0D9C6L, 0x12B7E950L, 0x8BBEB8EAL, 0xFCB9887CL,
0x62DD1DDFL, 0x15DA2D49L, 0x8CD37CF3L, 0xFBD44C65L,
0x4DB26158L, 0x3AB551CEL, 0xA3BC0074L, 0xD4BB30E2L,
0x4ADFA541L, 0x3DD895D7L, 0xA4D1C46DL, 0xD3D6F4FBL,
0x4369E96AL, 0x346ED9FCL, 0xAD678846L, 0xDA60B8D0L,
0x44042D73L, 0x33031DE5L, 0xAA0A4C5FL, 0xDD0D7CC9L,
0x5005713CL, 0x270241AAL, 0xBE0B1010L, 0xC90C2086L,
0x5768B525L, 0x206F85B3L, 0xB966D409L, 0xCE61E49FL,
0x5EDEF90EL, 0x29D9C998L, 0xB0D09822L, 0xC7D7A8B4L,
0x59B33D17L, 0x2EB40D81L, 0xB7BD5C3BL, 0xC0BA6CADL,
0xEDB88320L, 0x9ABFB3B6L, 0x03B6E20CL, 0x74B1D29AL,
0xEAD54739L, 0x9DD277AFL, 0x04DB2615L, 0x73DC1683L,
0xE3630B12L, 0x94643B84L, 0x0D6D6A3EL, 0x7A6A5AA8L,
0xE40ECF0BL, 0x9309FF9DL, 0x0A00AE27L, 0x7D079EB1L,
0xF00F9344L, 0x8708A3D2L, 0x1E01F268L, 0x6906C2FEL,
0xF762575DL, 0x806567CBL, 0x196C3671L, 0x6E6B06E7L,
0xFED41B76L, 0x89D32BE0L, 0x10DA7A5AL, 0x67DD4ACCL,
0xF9B9DF6FL, 0x8EBEEFF9L, 0x17B7BE43L, 0x60B08ED5L,
0xD6D6A3E8L, 0xA1D1937EL, 0x38D8C2C4L, 0x4FDFF252L,
0xD1BB67F1L, 0xA6BC5767L, 0x3FB506DDL, 0x48B2364BL,
0xD80D2BDAL, 0xAF0A1B4CL, 0x36034AF6L, 0x41047A60L,
0xDF60EFC3L, 0xA867DF55L, 0x316E8EEFL, 0x4669BE79L,
0xCB61B38CL, 0xBC66831AL, 0x256FD2A0L, 0x5268E236L,
0xCC0C7795L, 0xBB0B4703L, 0x220216B9L, 0x5505262FL,
0xC5BA3BBEL, 0xB2BD0B28L, 0x2BB45A92L, 0x5CB36A04L,
0xC2D7FFA7L, 0xB5D0CF31L, 0x2CD99E8BL, 0x5BDEAE1DL,
0x9B64C2B0L, 0xEC63F226L, 0x756AA39CL, 0x026D930AL,
0x9C0906A9L, 0xEB0E363FL, 0x72076785L, 0x05005713L,
0x95BF4A82L, 0xE2B87A14L, 0x7BB12BAEL, 0x0CB61B38L,
0x92D28E9BL, 0xE5D5BE0DL, 0x7CDCEFB7L, 0x0BDBDF21L,
0x86D3D2D4L, 0xF1D4E242L, 0x68DDB3F8L, 0x1FDA836EL,
0x81BE16CDL, 0xF6B9265BL, 0x6FB077E1L, 0x18B74777L,
0x88085AE6L, 0xFF0F6A70L, 0x66063BCAL, 0x11010B5CL,
0x8F659EFFL, 0xF862AE69L, 0x616BFFD3L, 0x166CCF45L,
0xA00AE278L, 0xD70DD2EEL, 0x4E048354L, 0x3903B3C2L,
0xA7672661L, 0xD06016F7L, 0x4969474DL, 0x3E6E77DBL,
0xAED16A4AL, 0xD9D65ADCL, 0x40DF0B66L, 0x37D83BF0L,
0xA9BCAE53L, 0xDEBB9EC5L, 0x47B2CF7FL, 0x30B5FFE9L,
0xBDBDF21CL, 0xCABAC28AL, 0x53B39330L, 0x24B4A3A6L,
0xBAD03605L, 0xCDD70693L, 0x54DE5729L, 0x23D967BFL,
0xB3667A2EL, 0xC4614AB8L, 0x5D681B02L, 0x2A6F2B94L,
0xB40BBE37L, 0xC30C8EA1L, 0x5A05DF1BL, 0x2D02EF8DL
};
// ------------------------------------------------------------------