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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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