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Decode lengths/distances from token

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This commit is contained in:
atxr 2024-02-20 12:32:33 +01:00
parent 4cdc14e48b
commit 84b33095b0
2 changed files with 35 additions and 3 deletions
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26
libmineziper/include/libmineziper_zip.h
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@ -1,6 +1,8 @@
#ifndef LIBMINEZIPER_ZIP_H
#define LIBMINEZIPER_ZIP_H
#include "libmineziper_bitstream.h"
#pragma pack(1)
#define START_EOCD_SEARCH 22
@ -9,9 +11,7 @@
#define CDH_SIG "PK\01\02"
#define DEFLATE 8
#define NUM_OF_CODE 26 * 2 + 10
const char* SYMBOLS =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
#define END_OF_BLOCK 256
typedef struct raw
{
@ -109,4 +109,24 @@ char* get_encoded_data(zip* in, int n);
void parse_zip(char* filename, zip* out);
void deflate(zip* in);
static const short length_codes[] = {
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27,
31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
static const char extra_bits_length_codes[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
1, 1, 2, 2, 2, 2, 3, 3, 3, 3,
4, 4, 4, 4, 5, 5, 5, 5, 0};
static const int distance_codes[] = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25,
33, 49, 65, 97, 129, 193, 257, 385, 513, 769,
1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
static const char extra_bits_distance_codes[] = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13};
short decode_length_token(bitstream* bs, int token);
int decode_distance_token(bitstream* bs, int token);
#endif

12
libmineziper/src/libmineziper_zip.c
View file

@ -51,3 +51,15 @@ char* get_encoded_data(zip* in, int n)
in->lfh[n]->extra_field_length;
}
short decode_length_token(bitstream* bs, int token)
{
token -= END_OF_BLOCK + 1;
int extra = get_bits(bs, extra_bits_length_codes[token]);
return length_codes[token] + extra;
}
int decode_distance_token(bitstream* bs, int token)
{
int extra = get_bits(bs, extra_bits_distance_codes[token]);
return distance_codes[token] + extra;
}