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- #include <u.h>
- #include <libc.h>
- #include <bio.h>
- #include "sky.h"
- static int hufvals[] = {
- 1, 1, 1, 1, 1, 1, 1, 1,
- 2, 2, 2, 2, 2, 2, 2, 2,
- 4, 4, 4, 4, 4, 4, 4, 4,
- 8, 8, 8, 8, 8, 8, 8, 8,
- 3, 3, 3, 3, 5, 5, 5, 5,
- 10, 10, 10, 10, 12, 12, 12, 12,
- 15, 15, 15, 15, 6, 6, 7, 7,
- 9, 9, 11, 11, 13, 13, 0, 14,
- };
- static int huflens[] = {
- 3, 3, 3, 3, 3, 3, 3, 3,
- 3, 3, 3, 3, 3, 3, 3, 3,
- 3, 3, 3, 3, 3, 3, 3, 3,
- 3, 3, 3, 3, 3, 3, 3, 3,
- 4, 4, 4, 4, 4, 4, 4, 4,
- 4, 4, 4, 4, 4, 4, 4, 4,
- 4, 4, 4, 4, 5, 5, 5, 5,
- 5, 5, 5, 5, 5, 5, 6, 6,
- };
- static int buffer;
- static int bits_to_go; /* Number of bits still in buffer */
- void
- start_inputing_bits(void)
- {
- bits_to_go = 0;
- }
- int
- input_huffman(Biobuf *infile)
- {
- int c;
- if(bits_to_go < 6) {
- c = Bgetc(infile);
- if(c < 0) {
- fprint(2, "input_huffman: unexpected EOF\n");
- exits("format");
- }
- buffer = (buffer<<8) | c;
- bits_to_go += 8;
- }
- c = (buffer >> (bits_to_go-6)) & 0x3f;
- bits_to_go -= huflens[c];
- return hufvals[c];
- }
- int
- input_nybble(Biobuf *infile)
- {
- int c;
- if(bits_to_go < 4) {
- c = Bgetc(infile);
- if(c < 0){
- fprint(2, "input_nybble: unexpected EOF\n");
- exits("format");
- }
- buffer = (buffer<<8) | c;
- bits_to_go += 8;
- }
- /*
- * pick off the first 4 bits
- */
- bits_to_go -= 4;
- return (buffer>>bits_to_go) & 0x0f;
- }
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