68 lines
1.2 KiB
C
68 lines
1.2 KiB
C
#include <stdio.h>
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#include <fcntl.h>
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#include <stdint.h>
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#define LEN_THRESH (3)
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FILE *in, *out;
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uint8_t data, datalast;
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uint16_t len, first=1;
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size_t off;
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uint16_t getrunlength(uint8_t data) {
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uint16_t count=1;
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while(fgetc(in)==data && count<65535) {
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if(feof(in))break;
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count++;
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}
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return count;
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}
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void writerle(uint8_t data, uint16_t len) {
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if(len<256) {
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fputc(0x5b, out);
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fputc(data, out);
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fputc(len & 0xff, out);
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} else {
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fputc(0x77, out);
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fputc(data, out);
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fputc(len & 0xff, out);
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fputc(len >> 8, out);
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}
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}
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void writeliteral(uint8_t data) {
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if(data==0x5b || data==0x77 || data==0x9b) {
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fputc(0x9b, out);
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}
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fputc(data, out);
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}
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int main(int argc, char** argv) {
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if((in=fopen(argv[1], "rb"))==NULL) {
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perror("could not open input file");
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return 1;
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}
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if((out=fopen(argv[2], "wb"))==NULL) {
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perror("could not open output file");
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fclose(in);
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return 1;
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}
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len=0;
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while(!feof(in)) {
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data=fgetc(in);
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if(feof(in))break;
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off=ftell(in);
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if((len=getrunlength(data)) > LEN_THRESH) {
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writerle(data, len);
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fseek(in, -1, SEEK_CUR);
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} else {
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fseek(in, off, SEEK_SET);
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writeliteral(data);
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}
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}
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fclose(out);
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fclose(in);
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return 0;
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}
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