// Fetches the next huffman code from the bitstream
byte get_next_code(jpeg_huffman_table cur_table)
{
word bit_string = 0;
byte cur_length = 1;
byte cur_code = 0;
int found = 0;
while (cur_length < 17)
{
bit_string <<= 1;
bit_string |= fetch_bits(1);
int code = get_huffman_code(bit_string, cur_length, cur_table);
if (code > -1)
{
cur_code = code;
found = 1;
break;
}
cur_length++;
}
if (!found)
{
printf("No code found!\n");
getc(stdin);
}
return cur_code;
}
int main(int argc, char *argv[])
{
FILE *fp, *kmp;
int i;
if (argc == 3) {
if (!(kmp = fopen(argv[1], "wb"))) {
fprintf(stderr, "Couldn't open file %s\n", argv[1]);
exit(EXIT_FAILURE);
}
if (!(fp = fopen(argv[2], "r"))) {
fprintf(stderr, "Couldn't open file %s\n", argv[2]);
exit(EXIT_FAILURE);
}
} else {
printf("USAGE: %s <outfile.kmp> <infile.txt>\n", argv[0]);
exit(EXIT_SUCCESS);
}
/* Create Huffman codebook from file */
struct huffcode codebook[ALPHLEN];
for (i=0; i<ALPHLEN; i++) {
codebook[i].set = 0;
}
get_huffman_code(fp, codebook);
/* Re-read input file, write each symbol's huffcode to temp file */
rewind(fp);
FILE *temp = tmpfile();
struct bitstream *bs = initbitstream(temp, BS_WRITE);
uint8_t byte;
while (fread(&byte, sizeof(uint8_t), 1, fp) == 1) {
if(!codebook[byte].set) {
printf("byte: %d\n", byte);
assert(0);
}
write_bitstring(bs, codebook[byte].code);
}
fclose(fp);
/* Close bitstream, get padding bits in last byte */
uint8_t padding = closebitstream(bs);
/* Write header to the output file */
write_header(kmp, padding, codebook);
/* Copy bitstream from tempfile to output file */
rewind(temp);
while (fread(&byte, sizeof(uint8_t), 1, temp) == 1) {
fwrite(&byte, sizeof(uint8_t), 1, kmp);
}
fclose(temp);
fclose(kmp);
return 0;
}
