mirror of
https://github.com/reactos/reactos.git
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119 lines
2.6 KiB
C
119 lines
2.6 KiB
C
/* ------------------- huffc.c -------------------- */
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#include "dflat.h"
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#include "htree.h"
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extern struct htree *ht;
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extern int root;
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extern int treect;
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static int lastchar = '\n';
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static void compress(FILE *, int, int);
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static void outbit(FILE *fo, int bit);
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static int fgetcx(FILE *fi)
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{
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int c;
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/* ------- bypass comments ------- */
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if ((c = fgetc(fi)) == ';' && lastchar == '\n')
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do {
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while (c != '\n' && c != EOF)
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c = fgetc(fi);
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} while (c == ';');
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lastchar = c;
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return c;
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}
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void main(int argc, char *argv[])
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{
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FILE *fi, *fo;
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int c;
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BYTECOUNTER bytectr = 0;
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if (argc < 3) {
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printf("\nusage: huffc infile outfile");
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exit(1);
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}
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if ((fi = fopen(argv[1], "rb")) == NULL) {
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printf("\nCannot open %s", argv[1]);
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exit(1);
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}
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if ((fo = fopen(argv[2], "wb")) == NULL) {
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printf("\nCannot open %s", argv[2]);
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fclose(fi);
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exit(1);
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}
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ht = calloc(256, sizeof(struct htree));
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/* - read the input file and count character frequency - */
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while ((c = fgetcx(fi)) != EOF) {
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c &= 255;
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ht[c].cnt++;
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bytectr++;
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}
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/* ---- build the huffman tree ---- */
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buildtree();
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/* --- write the byte count to the output file --- */
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fwrite(&bytectr, sizeof bytectr, 1, fo);
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/* --- write the tree count to the output file --- */
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fwrite(&treect, sizeof treect, 1, fo);
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/* --- write the root offset to the output file --- */
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fwrite(&root, sizeof root, 1, fo);
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/* -- write the tree to the output file -- */
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for (c = 256; c < treect; c++) {
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int lf = ht[c].left;
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int rt = ht[c].right;
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fwrite(&lf, sizeof lf, 1, fo);
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fwrite(&rt, sizeof rt, 1, fo);
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}
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/* ------ compress the file ------ */
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fseek(fi, 0L, 0);
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while ((c = fgetcx(fi)) != EOF)
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compress(fo, (c & 255), 0);
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outbit(fo, -1);
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fclose(fi);
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fclose(fo);
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free(ht);
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exit(0);
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}
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/* ---- compress a character value into a bit stream ---- */
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static void compress(FILE *fo, int h, int child)
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{
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if (ht[h].parent != -1)
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compress(fo, ht[h].parent, h);
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if (child) {
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if (child == ht[h].right)
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outbit(fo, 0);
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else if (child == ht[h].left)
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outbit(fo, 1);
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}
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}
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static char out8;
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static int ct8;
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/* -- collect and write bits to the compressed output file -- */
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static void outbit(FILE *fo, int bit)
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{
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if (ct8 == 8 || bit == -1) {
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while (ct8 < 8) {
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out8 <<= 1;
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ct8++;
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}
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fputc(out8, fo);
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ct8 = 0;
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}
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out8 = (out8 << 1) | bit;
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ct8++;
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}
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