lzw压缩算法的c语言实现1 程序由五个模块组成。

(1) lzw.h 定义了一些基本的数据结构，常量，还有变量的初始化等。

#ifndef __LZW_H__#define __LZW_H__//------------------------------------------------------------------------------#include <stdio.h>#include <stdlib.h>#include <windows.h>#include <memory.h>//------------------------------------------------------------------------------#define LZW_BASE 0x102// The code base#define CODE_LEN 12 // Max code length#define TABLE_LEN 4099 // It must be prime number and bigger than 2^CODE_LEN=4096.// Such as 5051 is also ok.#define BUFFERSIZE 1024//------------------------------------------------------------------------------typedef struct{HANDLE h_sour; // Source file handle.HANDLE h_dest; // Destination file handle.HANDLE h_suffix; // Suffix table handle.HANDLE h_prefix; // Prefix table handle.HANDLE h_code; // Code table handle.LPWORD lp_prefix; // Prefix table head pointer.LPBYTE lp_suffix; // Suffix table head pointer.LPWORD lp_code; // Code table head pointer.WORD code;WORD prefix;BYTE suffix;BYTE cur_code_len; // Current code length.[ used in Dynamic-Code-Length mode ] }LZW_DATA,*PLZW_DATA;typedef struct{WORD top;WORD index;LPBYTE lp_buffer;HANDLE h_buffer;BYTE by_left;DWORD dw_buffer;BOOL end_flag;}BUFFER_DATA,*PBUFFER_DATA;typedef struct //Stack used in decode{WORD index;HANDLE h_stack;LPBYTE lp_stack;}STACK_DATA,*PSTACK_DATA;//------------------------------------------------------------------------------VOID stack_create( PSTACK_DATA stack ){stack->h_stack = GlobalAlloc( GHND , TABLE_LEN*sizeof(BYTE) );stack->lp_stack = GlobalLock( stack->h_stack );stack->index = 0;}//------------------------------------------------------------------------------VOID stack_destory( PSTACK_DATA stack ){GlobalUnlock( stack->h_stack );GlobalFree ( stack->h_stack );}//------------------------------------------------------------------------------VOID buffer_create( PBUFFER_DATA buffer ){buffer->h_buffer = GlobalAlloc( GHND, BUFFERSIZE*sizeof(BYTE) ); buffer->lp_buffer = GlobalLock( buffer->h_buffer );buffer->top = 0;buffer->index = 0;buffer->by_left = 0;buffer->dw_buffer = 0;buffer->end_flag = FALSE;}//------------------------------------------------------------------------------VOID buffer_destory( PBUFFER_DATA buffer ){GlobalUnlock( buffer->h_buffer );GlobalFree ( buffer->h_buffer );}//------------------------------------------------------------------------------VOID re_init_lzw( PLZW_DATA lzw ) //When code table reached its top it should { //be reinitialized.memset( lzw->lp_code, 0xFFFF, TABLE_LEN*sizeof(WORD) );lzw->code = LZW_BASE;lzw->cur_code_len = 9;}//------------------------------------------------------------------------------VOID lzw_create(PLZW_DATA lzw, HANDLE h_sour, HANDLE h_dest) {WORD i;lzw->h_code = GlobalAlloc( GHND, TABLE_LEN*sizeof(WORD) );lzw->h_prefix = GlobalAlloc( GHND, TABLE_LEN*sizeof(WORD) );lzw->h_suffix = GlobalAlloc( GHND, TABLE_LEN*sizeof(BYTE) );lzw->lp_code = GlobalLock( lzw->h_code );lzw->lp_prefix = GlobalLock( lzw->h_prefix );lzw->lp_suffix = GlobalLock( lzw->h_suffix );lzw->code = LZW_BASE;lzw->cur_code_len = 9;lzw->h_sour = h_sour;lzw->h_dest = h_dest;memset( lzw->lp_code, 0xFFFF, TABLE_LEN*sizeof(WORD) );}//------------------------------------------------------------------------------VOID lzw_destory(PLZW_DATA lzw){GlobalUnlock( lzw->h_code );GlobalUnlock( lzw->h_prefix );GlobalUnlock( lzw->h_suffix );GlobalFree( lzw->h_code );GlobalFree( lzw->h_prefix );GlobalFree( lzw->h_suffix );}//------------------------------------------------------------------------------#endif(2) fileio.h 定义了一些文件操作#ifndef __FILEIO_H__#define __FILEIO_H__//------------------------------------------------------------------------------#include <stdio.h>#include <stdlib.h>#include <windows.h>//------------------------------------------------------------------------------HANDLE file_handle(CHAR* file_name){HANDLE h_file;h_file = CreateFile(file_name,GENERIC_READ|GENERIC_WRITE,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,OPEN_ALWAYS,0,NULL);return h_file;}//------------------------------------------------------------------------------WORD load_buffer(HANDLE h_sour, PBUFFER_DATA buffer) // Load file to buffer{DWORD ret;ReadFile(h_sour,buffer->lp_buffer,BUFFERSIZE,&ret,NULL);buffer->index = 0;buffer->top = (WORD)ret;return (WORD)ret;}//------------------------------------------------------------------------------WORD empty_buffer( PLZW_DATA lzw, PBUFFER_DATA buffer)// Output buffer to file {DWORD ret;if(buffer->end_flag) // The flag mark the end of decode{if( buffer->by_left ){buffer->lp_buffer[ buffer->index++ ] =(BYTE)( buffer->dw_buffer >>32-buffer->by_left )<<(8-buffer->by_left);}}WriteFile(lzw->h_dest, buffer->lp_buffer,buffer->index,&ret,NULL);buffer->index = 0;buffer->top = ret;return (WORD)ret;}//------------------------------------------------------------------------------#endif(3) hash.h 定义了压缩时所用的码表操作函数，为了快速查找使用了hash算法，还有处理hash冲突的函数#ifndef __HASH_H__#define __HASH_H__//------------------------------------------------------------------------------#include <stdio.h>#include <stdlib.h>#include <windows.h>//------------------------------------------------------------------------------#define DIV TABLE_LEN#define HASHSTEP 13 // It should bigger than 0.//------------------------------------------------------------------------------WORD get_hash_index( PLZW_DATA lzw ){DWORD tmp;WORD result;DWORD prefix;DWORD suffix;prefix = lzw->prefix;suffix = lzw->suffix;tmp = prefix<<8 | suffix;result = tmp % DIV;return result;}//------------------------------------------------------------------------------WORD re_hash_index( WORD hash ) // If hash conflict occured we must recalculate { // hash index .WORD result;result = hash + HASHSTEP;result = result % DIV;return result;}//------------------------------------------------------------------------------BOOL in_table( PLZW_DATA lzw ) // To find whether current code is already in table. {BOOL result;WORD hash;hash = get_hash_index( lzw );if( lzw->lp_code[ hash ] == 0xFFFF ){result = FALSE;}else{if( lzw->lp_prefix[ hash ] == lzw->prefix &&lzw->lp_suffix[ hash ] == lzw->suffix ){result = TRUE;}else{result = FALSE;while( lzw->lp_code[ hash ] != 0xFFFF ){if( lzw->lp_prefix[ hash ] == lzw->prefix &&lzw->lp_suffix[ hash ] == lzw->suffix ){result = TRUE;break;}hash = re_hash_index( hash );}}}return result;}//------------------------------------------------------------------------------WORD get_code( PLZW_DATA lzw ){WORD hash;WORD code;hash = get_hash_index( lzw );if( lzw->lp_prefix[ hash ] == lzw->prefix &&lzw->lp_suffix[ hash ] == lzw->suffix ){code = lzw->lp_code[ hash ];}else{while( lzw->lp_prefix[ hash ] != lzw->prefix ||lzw->lp_suffix[ hash ] != lzw->suffix ){hash = re_hash_index( hash );}code = lzw->lp_code[ hash ];}return code;}//------------------------------------------------------------------------------ VOID insert_table( PLZW_DATA lzw ){WORD hash;hash = get_hash_index( lzw );if( lzw->lp_code[ hash ] == 0xFFFF ){lzw->lp_prefix[ hash ] = lzw->prefix;lzw->lp_suffix[ hash ] = lzw->suffix;lzw->lp_code[ hash ] = lzw->code;}else{while( lzw->lp_code[ hash ] != 0xFFFF ){hash = re_hash_index( hash );}lzw->lp_prefix[ hash ] = lzw->prefix;lzw->lp_suffix[ hash ] = lzw->suffix;lzw->lp_code[ hash ] = lzw->code;}}//------------------------------------------------------------------------------ #endif(4) encode.h 压缩程序主函数#ifndef __ENCODE_H__#define __ENCODE_H__//------------------------------------------------------------------------------#include <stdio.h>#include <stdlib.h>#include <windows.h>//------------------------------------------------------------------------------VOID output_code( DWORD code ,PBUFFER_DATA out, PLZW_DATA lzw) {out->dw_buffer |= code << ( 32 - out->by_left - lzw->cur_code_len );out->by_left += lzw->cur_code_len;while( out->by_left >= 8 ){if( out->index == BUFFERSIZE ){empty_buffer( lzw,out);}out->lp_buffer[ out->index++ ] = (BYTE)( out->dw_buffer >> 24 );out->dw_buffer <<= 8;out->by_left -= 8;}}//------------------------------------------------------------------------------VOID do_encode( PBUFFER_DATA in, PBUFFER_DATA out, PLZW_DATA lzw) {WORD prefix;while( in->index != in->top ){if( !in_table(lzw) ){// current code not in code table// then add it to table and output prefixinsert_table(lzw);prefix = lzw->suffix;output_code( lzw->prefix ,out ,lzw );lzw->code++;if( lzw->code == (WORD)1<< lzw->cur_code_len ){// code reached current code top(1<<cur_code_len) // then current code length add onelzw->cur_code_len++;if( lzw->cur_code_len == CODE_LEN + 1 ){re_init_lzw( lzw );}}}else{// current code already in code table// then output nothingprefix = get_code(lzw);}lzw->prefix = prefix;lzw->suffix = in->lp_buffer[ in->index++ ];}}//------------------------------------------------------------------------------ VOID encode(HANDLE h_sour,HANDLE h_dest){LZW_DATA lzw;BUFFER_DATA in ;BUFFER_DATA out;BOOL first_run = TRUE;lzw_create( &lzw ,h_sour,h_dest );buffer_create( &in );buffer_create( &out );while( load_buffer( h_sour, &in ) ){if( first_run ){// File length should be considered but here we simply// believe file length bigger than 2 bytes.lzw.prefix = in.lp_buffer[ in.index++ ];lzw.suffix = in.lp_buffer[ in.index++ ];first_run = FALSE;}do_encode(&in , &out, &lzw);}output_code(lzw.prefix, &out , &lzw);output_code(lzw.suffix, &out , &lzw);out.end_flag = TRUE;empty_buffer( &lzw,&out);lzw_destory( &lzw );buffer_destory( &in );buffer_destory( &out );}//------------------------------------------------------------------------------#endif(5) decode.h 解压函数主函数#ifndef __DECODE_H__#define __DECODE_H__//------------------------------------------------------------------------------#include <stdio.h>#include <stdlib.h>#include <windows.h>//------------------------------------------------------------------------------VOID out_code( WORD code ,PBUFFER_DATA buffer,PLZW_DATA lzw,PSTACK_DATA stack){WORD tmp;if( code < 0x100 ){stack->lp_stack[ stack->index++ ] = code;}else{stack->lp_stack[ stack->index++ ] = lzw->lp_suffix[ code ];tmp = lzw->lp_prefix[ code ];while( tmp > 0x100 ){stack->lp_stack[ stack->index++ ] = lzw->lp_suffix[ tmp ];tmp = lzw->lp_prefix[ tmp ];}stack->lp_stack[ stack->index++ ] = (BYTE)tmp;}while( stack->index ){if( buffer->index == BUFFERSIZE ){empty_buffer(lzw,buffer);}buffer->lp_buffer[ buffer->index++ ] = stack->lp_stack[ --stack->index ] ; }}//------------------------------------------------------------------------------VOID insert_2_table(PLZW_DATA lzw ){lzw->lp_code[ lzw->code ] = lzw->code;lzw->lp_prefix[ lzw->code ] = lzw->prefix;lzw->lp_suffix[ lzw->code ] = lzw->suffix;lzw->code++;if( lzw->code == ((WORD)1<<lzw->cur_code_len)-1 ){lzw->cur_code_len++;if( lzw->cur_code_len == CODE_LEN+1 )lzw->cur_code_len = 9;}if(lzw->code >= 1<<CODE_LEN ){re_init_lzw(lzw);}}//------------------------------------------------------------------------------WORD get_next_code( PBUFFER_DATA buffer , PLZW_DATA lzw ) {BYTE next;WORD code;while( buffer->by_left < lzw->cur_code_len ){if( buffer->index == BUFFERSIZE )load_buffer( lzw->h_sour, buffer );}next = buffer->lp_buffer[ buffer->index++ ];buffer->dw_buffer |= (DWORD)next << (24-buffer->by_left);buffer->by_left += 8;}code = buffer->dw_buffer >> ( 32 - lzw->cur_code_len );buffer->dw_buffer <<= lzw->cur_code_len;buffer->by_left -= lzw->cur_code_len;return code;}//------------------------------------------------------------------------------VOID do_decode( PBUFFER_DATA in, PBUFFER_DATA out, PLZW_DATA lzw, PSTACK_DATA stack){WORD code;WORD tmp;while( in->index != in->top ){code = get_next_code( in ,lzw );if( code < 0x100 ){// code already in table// then simply output the codelzw->suffix = (BYTE)code;}else{if( code < lzw->code ){// code also in table// then output code chaintmp = lzw->lp_prefix[ code ];while( tmp > 0x100 ){tmp = lzw->lp_prefix[ tmp ];}lzw->suffix = (BYTE)tmp;}else// code == lzw->code// code not in table// add code into table// and out put codetmp = lzw->prefix;while( tmp > 0x100 ){tmp = lzw->lp_prefix[ tmp ];}lzw->suffix = (BYTE)tmp;}}insert_2_table( lzw );out_code(code,out,lzw,stack);lzw->prefix = code;}}//------------------------------------------------------------------------------ VOID decode( HANDLE h_sour, HANDLE h_dest ){LZW_DATA lzw;BUFFER_DATA in ;BUFFER_DATA out;STACK_DATA stack;BOOL first_run;first_run = TRUE;lzw_create( &lzw ,h_sour,h_dest );buffer_create( &in );buffer_create( &out );stack_create(&stack );while( load_buffer( h_sour, &in ) ){if( first_run ){lzw.prefix = get_next_code( &in, &lzw );lzw.suffix = lzw.prefix;out_code(lzw.prefix, &out, &lzw , &stack);first_run = FALSE;}do_decode(&in , &out, &lzw, &stack);}empty_buffer( &lzw,&out);lzw_destory( &lzw );buffer_destory( &in );buffer_destory( &out );stack_destory( &stack);}#endif2 下面给出一个应用上面模块的简单例子#include <stdio.h>#include <stdlib.h>//------------------------------------------------------------------------------#include "lzw.h"#include "hash.h"#include "fileio.h"#include "encode.h"#include "decode.h"//------------------------------------------------------------------------------ HANDLE h_file_sour;HANDLE h_file_dest;HANDLE h_file;CHAR* file_name_in = "d:\\code.c";CHAR* file_name_out= "d:\\encode.e";CHAR* file_name = "d:\\decode.d";//------------------------------------------------------------------------------ int main(int argc, char *argv[]){h_file_sour = file_handle(file_name_in);h_file_dest = file_handle(file_name_out);h_file = file_handle(file_name);encode(h_file_sour, h_file_dest); // decode(h_file_dest,h_file);CloseHandle(h_file_sour);CloseHandle(h_file_dest);CloseHandle(h_file);return 0;}。