Intel Extensible Firmware Interface - Manual (Page 965)

Version 1.10 12/01/02 H-1
Appendix H
Compression Source Code
/*++
Copyright (c) 2001–2002 Intel Corporation
Module Name:
Compress.c
Abstract:
Compression routine. The compression algorithm is a mixture of
LZ77 and Huffman Coding. LZ77 transforms the source data into a
sequence of Original Characters and Pointers to repeated strings.
This sequence is further divided into Blocks and Huffman codings
are applied to each Block.
Revision History:
--*/
#include <string.h>
#include <stdlib.h>
#include "eficommon.h"
//
// Macro Definitions
//
typedef INT16 NODE;
#define UINT8_MAX 0xff
#define UINT8_BIT 8
#define THRESHOLD 3
#define INIT_CRC 0
#define WNDBIT 13
#define WNDSIZ (1U << WNDBIT)
#define MAXMATCH 256
#define PERC_FLAG 0x8000U
#define CODE_BIT 16
#define NIL 0
#define MAX_HASH_VAL (3 * WNDSIZ + (WNDSIZ / 512 + 1) * UINT8_MAX)
#define HASH(p, c) ((p) + ((c) << (WNDBIT - 9)) + WNDSIZ * 2)
#define CRCPOLY 0xA001
#define UPDATE_CRC(c) mCrc = mCrcTable[(mCrc ^ (c)) & 0xFF] ^ (mCrc >>
UINT8_BIT)
//
// C: the Char&Len Set; P: the Position Set; T: the exTra Set
//
#define NC (UINT8_MAX + MAXMATCH + 2 - THRESHOLD)
#define CBIT 9
#define NP (WNDBIT + 1)
#define PBIT 4