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rld.c
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rld.c
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#include <stdio.h>
#define null ((void *)0)
FILE * input = null;
FILE * output = null;
unsigned char tag = 0xff;
void print_usage_info()
{
printf("\nUsage: rld input_file output_file\n");
printf("Output: decoded version of input_file\n");
printf("Details: this program decodes rle encoded binary files.\n");
}
void print_error(char *description)
{
printf("\nError: %s\n", description);
print_usage_info();
printf("\n");
}
void rle_decode(FILE *in, FILE *out)
{
int rbyte, wbyte;
int i, count;
tag = (unsigned char)fgetc(in);
while ((rbyte = fgetc(in)) != EOF)
{
if (rbyte != tag)
{
wbyte = rbyte;
fputc(wbyte, out);
}
else
{
count = fgetc(in);
for (i = 0; i < count; i++)
{
fputc(wbyte, out);
}
}
}
}
int main(int argc, char **argv)
{
if (argc != 3)
{
print_usage_info();
printf("\n");
return 0;
}
input = fopen(argv[1], "r");
if (input == null)
{
print_error("Cannot open input file! Access denied!");
return -1;
}
output = fopen(argv[2], "w");
if (output == null)
{
print_error("Cannot open output file! Access denied!");
if (input != null)
fclose(input);
return -1;
}
rle_decode(input, output);
fclose(input);
fclose(output);
return 0;
}