我使用了https://oku.edu.mie-u.ac.jp/~okumura/compression/lzss.c
中的代码此代码用于文件压缩。我已经为给定的字符串修改了它。例如：
d（2306）：AuthorisationScheme：RADIUSserveratfd04：BD3：80e8：1 :: 1usingPAPD / 6LoWPANd（2306）：WritingModule：SecurityConfigD / 6LoWPANd（2306）：WritingModule：RunCoordinatorD / 6LoWPANd（2306）：RequestingmoduleaddressD / 6LoWPANd（2306） ：WritingModule：GetAddressD /智能卡的JNI（2781）：SmartCard_state_update_callback：状态= 6D / SmartCardNative（2781）：状态= 6D /智能卡（2781）：PN532Smartcard_loop_threadexitD /智能卡的JNI（2781）：SmartCard_loop_thread：SMARTCARD_STATUS_ABORTD /智能卡（2781）： Smartcard_loop_uninitD /智能卡（2781）：2D / serialcomm_pn532（2781）：PN532：Readingfrom的/ dev / ttyUSB0 - ＆GT; d /智能卡（2781）：接收段（0x3）fromPN532：（DATABUF [0]：为0x1）（0x1f5988）d /智能卡（2781）：ReceivedStatusfromPN532：OK（CMD：0X2）d /智能卡的JNI（2781）：SmartCard_listener_update_callbackD /智能卡（2781）：接收（0x1c2）fromPN532：（DATABUF [0]：0x32）（0x1f5988）d /智能卡（2781）：VD（2306）：AuthorisationScheme：RADIUSserveratfd04：BD3：80e8：1 :: 1usingPAPD / 6LoWPANd（2306）：
我面临的问题是，如果我想压缩包含此文件的文件，代码就能够做到这一点。但是我修改过的代码却没有什么问题。压缩文件的最后2位是不同的。虽然文件和缓冲区的内容完全相同。
原始代码正在从文件中读取。在这里，我提供了相同内容的字符串。
代码在这里：
/* LZSS encoder-decoder (c) Haruhiko Okumura */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define EI 11 /* typically 10..13 */
#define EJ 4 /* typically 4..5 */
#define P 1 /* If match length <= P then output one character */
#define N (1 << EI) /* buffer size */
#define F ((1 << EJ) + P) /* lookahead buffer size */
int bit_buffer = 0, bit_mask = 128;
unsigned long codecount = 0, textcount = 0;
unsigned char buffer[N * 2];
FILE *infile, *outfile, *outfile2, *outfile3;
/*----*/
unsigned long payload_i = 0;
int tt = 0;
unsigned int buf_load[16000];
unsigned char *string_buf= "d(2306):AuthorisationScheme:RADIUSserveratfd04:bd3:80e8:1::1usingPAPD/6LoWPANd(2306):WritingModule:SecurityConfigD/6LoWPANd(2306):WritingModule:RunCoordinatorD/6LoWPANd(2306):RequestingmoduleaddressD/6LoWPANd(2306):WritingModule:GetAddressD/smartcard-jni(2781):SmartCard_state_update_callback:status=6D/SmartCardNative(2781):status=6D/smartcard(2781):PN532Smartcard_loop_threadexitD/smartcard-jni(2781):SmartCard_loop_thread:SMARTCARD_STATUS_ABORTD/smartcard(2781):Smartcard_loop_uninitD/smartcard(2781):2D/serialcomm_pn532(2781):PN532:Readingfrom/dev/ttyUSB0-->D/smartcard(2781):Received(0x3)fromPN532:(dataBuf[0]:0x1)(0x1f5988)D/smartcard(2781):ReceivedStatusfromPN532:OK(cmd:0x2)D/smartcard-jni(2781):SmartCard_listener_update_callbackD/smartcard(2781):Received(0x1c2)fromPN532:(dataBuf[0]:0x32)(0x1f5988)D/smartcard(2781):vd(2306):AuthorisationScheme:RADIUSserveratfd04:bd3:80e8:1::1usingPAPD/6LoWPANd(2306):";
/*----*/
void error(void)
{
printf("Output error\n"); exit(1);
}
void putbit1(void)
{
outfile2 = fopen("file2.lzss", "a");
bit_buffer |= bit_mask;
if ((bit_mask >>= 1) == 0) {
/*----*/
buf_load[payload_i] = bit_buffer;
if (fputc(buf_load[payload_i], outfile3) == EOF) error();
payload_i++;
/*----*/
if (fputc(bit_buffer, outfile2) == EOF) error();
if (fputc(bit_buffer, outfile) == EOF) error();
bit_buffer = 0; bit_mask = 128; codecount++;
}
fclose(outfile2);
}
void putbit0(void)
{
outfile2 = fopen("file2.lzss", "a");
if ((bit_mask >>= 1) == 0) {
/*----*/
buf_load[payload_i] = bit_buffer;
if (fputc(buf_load[payload_i], outfile3) == EOF) error();
payload_i++;
/*----*/
if (fputc(bit_buffer, outfile2) == EOF) error();
if (fputc(bit_buffer, outfile) == EOF) error();
bit_buffer = 0; bit_mask = 128; codecount++;
}
fclose(outfile2);
}
void flush_bit_buffer(void)
{
outfile2 = fopen("file2.lzss", "a");
if (bit_mask != 128) {
if (fputc(buf_load[payload_i], outfile3) == EOF) error();
if (fputc(bit_buffer, outfile2) == EOF) error();
if (fputc(bit_buffer, outfile) == EOF) error();
codecount++;
}
fclose(outfile2);
}
void output1(int c)
{
int mask;
putbit1();
mask = 256;
while (mask >>= 1) {
if (c & mask) putbit1();
else putbit0();
}
}
void output2(int x, int y)
{
int mask;
putbit0();
mask = N;
while (mask >>= 1) {
if (x & mask) putbit1();
else putbit0();
}
mask = (1 << EJ);
while (mask >>= 1) {
if (y & mask) putbit1();
else putbit0();
}
}
void encode(void)
{
int i, j, f1, x, y, r, s, bufferend, c;
for (i = 0; i < N - F; i++) buffer[i] = ' ';
for (i = N - F; i < N * 2; i++) {
if ((c = fgetc(infile)) == EOF) break;
if((c = string_buf[tt++]) == '\0') break;
buffer[i] = c; textcount++; //tt++;
}
bufferend = i; r = N - F; s = 0;
while (r < bufferend) {
f1 = (F <= bufferend - r) ? F : bufferend - r;
x = 0; y = 1; c = buffer[r];
for (i = r - 1; i >= s; i--)
if (buffer[i] == c) {
for (j = 1; j < f1; j++)
if (buffer[i + j] != buffer[r + j]) break;
if (j > y) {
x = i; y = j;
}
}
if (y <= P) output1(c);
else output2(x & (N - 1), y - 2);
r += y; s += y;
if (r >= N * 2 - F) {
for (i = 0; i < N; i++) buffer[i] = buffer[i + N];
bufferend -= N; r -= N; s -= N;
while (bufferend < N * 2) {
if ((c = fgetc(infile)) == EOF) break;
if((c = string_buf[tt++]) == '\0') break;
//tt++;
buffer[bufferend++] = c; textcount++;
}
}
}
flush_bit_buffer();
printf("text: %ld bytes\n", textcount);
printf("code: %ld bytes (%ld%%)\n",
codecount, (codecount * 100) / textcount);
}
int getbit(int n) /* get n bits */
{
int i, x;
static int buf, mask = 0;
x = 0;
for (i = 0; i < n; i++) {
if (mask == 0) {
if ((buf = fgetc(infile)) == EOF) return EOF;
mask = 128;
}
x <<= 1;
if (buf & mask) x++;
mask >>= 1;
}
return x;
}
void decode(void)
{
int i, j, k, r, c;
for (i = 0; i < N - F; i++) buffer[i] = ' ';
r = N - F;
while ((c = getbit(1)) != EOF) {
if (c) {
if ((c = getbit(8)) == EOF) break;
fputc(c, outfile);
buffer[r++] = c; r &= (N - 1);
} else {
if ((i = getbit(EI)) == EOF) break;
if ((j = getbit(EJ)) == EOF) break;
for (k = 0; k <= j + 1; k++) {
c = buffer[(i + k) & (N - 1)];
fputc(c, outfile);
buffer[r++] = c; r &= (N - 1);
}
}
}
}
int main(int argc, char *argv[])
{
int enc;
char *s;
memset(buf_load, '\0', sizeof(buf_load));
outfile3 = fopen ("file1.lzss", "wb");
if (argc != 4) {
printf("Usage: lzss e/d infile outfile\n\te = encode\td = decode\n");
return 1;
}
s = argv[1];
if (s[1] == 0 && (*s == 'd' || *s == 'D' || *s == 'e' || *s == 'E'))
enc = (*s == 'e' || *s == 'E');
else {
printf("? %s\n", s); return 1;
}
if ((infile = fopen(argv[2], "rb")) == NULL) {
printf("? %s\n", argv[2]); return 1;
}
if ((outfile = fopen(argv[3], "wb")) == NULL) {
printf("? %s\n", argv[3]); return 1;
}
if (enc) encode(); else decode();
fclose(infile); fclose(outfile);
fclose(outfile3);
return 0;
}
看起来问题在于缓冲区读写与文件读写。在文件读写中，指针增加到下一个mem loc并以相同的方式读写。在字符串中，通过递增索引读取每个数组，然后将压缩值写入文件写入文件中。在文件中，它被读作二进制（wb），在字符串中它被读作数组元素。可能有问题吗？需要专家的建议。
答案 0 :(得分：0)
void flush_bit_buffer(void)
{
outfile2 = fopen("file2.lzss", "a");
if (bit_mask != 128) {
flush_bit[payload_i] = bit_buffer; /*This last bit should be put which I missed. It solved my issue*/
if (fputc(buf_load[payload_i], outfile3) == EOF) error();
if (fputc(bit_buffer, outfile2) == EOF) error();
if (fputc(bit_buffer, outfile) == EOF) error();
codecount++;
}
fclose(outfile2);
}
我通过在代码段中添加该行来解决它。我需要添加最后一位缓冲区来解决这个问题。