-
Notifications
You must be signed in to change notification settings - Fork 464
/
sdd1emu.cpp
333 lines (302 loc) · 9.07 KB
/
sdd1emu.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
/*****************************************************************************\
Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
This file is licensed under the Snes9x License.
For further information, consult the LICENSE file in the root directory.
\*****************************************************************************/
/* S-DD1 decompressor
*
* Based on code and documentation by Andreas Naive, who deserves a great deal
* of thanks and credit for figuring this out.
*
* Andreas says:
* The author is greatly indebted with The Dumper, without whose help and
* patience providing him with real S-DD1 data the research had never been
* possible. He also wish to note that in the very beggining of his research,
* Neviksti had done some steps in the right direction. By last, the author is
* indirectly indebted to all the people that worked and contributed in the
* S-DD1 issue in the past.
*/
#include "port.h"
#include "sdd1emu.h"
static int valid_bits;
static uint16 in_stream;
static uint8 *in_buf;
static uint8 bit_ctr[8];
static uint8 context_states[32];
static int context_MPS[32];
static int bitplane_type;
static int high_context_bits;
static int low_context_bits;
static int prev_bits[8];
static struct {
uint8 code_size;
uint8 MPS_next;
uint8 LPS_next;
} evolution_table[] = {
/* 0 */ { 0,25,25},
/* 1 */ { 0, 2, 1},
/* 2 */ { 0, 3, 1},
/* 3 */ { 0, 4, 2},
/* 4 */ { 0, 5, 3},
/* 5 */ { 1, 6, 4},
/* 6 */ { 1, 7, 5},
/* 7 */ { 1, 8, 6},
/* 8 */ { 1, 9, 7},
/* 9 */ { 2,10, 8},
/* 10 */ { 2,11, 9},
/* 11 */ { 2,12,10},
/* 12 */ { 2,13,11},
/* 13 */ { 3,14,12},
/* 14 */ { 3,15,13},
/* 15 */ { 3,16,14},
/* 16 */ { 3,17,15},
/* 17 */ { 4,18,16},
/* 18 */ { 4,19,17},
/* 19 */ { 5,20,18},
/* 20 */ { 5,21,19},
/* 21 */ { 6,22,20},
/* 22 */ { 6,23,21},
/* 23 */ { 7,24,22},
/* 24 */ { 7,24,23},
/* 25 */ { 0,26, 1},
/* 26 */ { 1,27, 2},
/* 27 */ { 2,28, 4},
/* 28 */ { 3,29, 8},
/* 29 */ { 4,30,12},
/* 30 */ { 5,31,16},
/* 31 */ { 6,32,18},
/* 32 */ { 7,24,22}
};
static uint8 run_table[128] = {
128, 64, 96, 32, 112, 48, 80, 16, 120, 56, 88, 24, 104, 40, 72,
8, 124, 60, 92, 28, 108, 44, 76, 12, 116, 52, 84, 20, 100, 36,
68, 4, 126, 62, 94, 30, 110, 46, 78, 14, 118, 54, 86, 22, 102,
38, 70, 6, 122, 58, 90, 26, 106, 42, 74, 10, 114, 50, 82, 18,
98, 34, 66, 2, 127, 63, 95, 31, 111, 47, 79, 15, 119, 55, 87,
23, 103, 39, 71, 7, 123, 59, 91, 27, 107, 43, 75, 11, 115, 51,
83, 19, 99, 35, 67, 3, 125, 61, 93, 29, 109, 45, 77, 13, 117,
53, 85, 21, 101, 37, 69, 5, 121, 57, 89, 25, 105, 41, 73, 9,
113, 49, 81, 17, 97, 33, 65, 1
};
static inline uint8 GetCodeword(int bits){
uint8 tmp;
if(!valid_bits){
in_stream|=*(in_buf++);
valid_bits=8;
}
in_stream<<=1;
valid_bits--;
in_stream^=0x8000;
if(in_stream&0x8000) return 0x80+(1<<bits);
tmp=(in_stream>>8) | (0x7f>>bits);
in_stream<<=bits;
valid_bits-=bits;
if(valid_bits<0){
in_stream |= (*(in_buf++))<<(-valid_bits);
valid_bits+=8;
}
return run_table[tmp];
}
static inline uint8 GolombGetBit(int code_size){
if(!bit_ctr[code_size]) bit_ctr[code_size]=GetCodeword(code_size);
bit_ctr[code_size]--;
if(bit_ctr[code_size]==0x80){
bit_ctr[code_size]=0;
return 2; /* secret code for 'last zero'. ones are always last. */
}
return (bit_ctr[code_size]==0)?1:0;
}
static inline uint8 ProbGetBit(uint8 context){
uint8 state=context_states[context];
uint8 bit=GolombGetBit(evolution_table[state].code_size);
if(bit&1){
context_states[context]=evolution_table[state].LPS_next;
if(state<2){
context_MPS[context]^=1;
return context_MPS[context]; /* just inverted, so just return it */
} else{
return context_MPS[context]^1; /* we know bit is 1, so use a constant */
}
} else if(bit){
context_states[context]=evolution_table[state].MPS_next;
/* zero here, zero there, no difference so drop through. */
}
return context_MPS[context]; /* we know bit is 0, so don't bother xoring */
}
static inline uint8 GetBit(uint8 cur_bitplane){
uint8 bit;
bit=ProbGetBit(((cur_bitplane&1)<<4)
| ((prev_bits[cur_bitplane]&high_context_bits)>>5)
| (prev_bits[cur_bitplane]&low_context_bits));
prev_bits[cur_bitplane] <<= 1;
prev_bits[cur_bitplane] |= bit;
return bit;
}
void SDD1_decompress(uint8 *out, uint8 *in, int len){
uint8 bit, i, plane;
uint8 byte1, byte2;
if(len==0) len=0x10000;
bitplane_type=in[0]>>6;
switch(in[0]&0x30){
case 0x00:
high_context_bits=0x01c0;
low_context_bits =0x0001;
break;
case 0x10:
high_context_bits=0x0180;
low_context_bits =0x0001;
break;
case 0x20:
high_context_bits=0x00c0;
low_context_bits =0x0001;
break;
case 0x30:
high_context_bits=0x0180;
low_context_bits =0x0003;
break;
}
in_stream=(in[0]<<11) | (in[1]<<3);
valid_bits=5;
in_buf=in+2;
memset(bit_ctr, 0, sizeof(bit_ctr));
memset(context_states, 0, sizeof(context_states));
memset(context_MPS, 0, sizeof(context_MPS));
memset(prev_bits, 0, sizeof(prev_bits));
switch(bitplane_type){
case 0:
while(1) {
for(byte1=byte2=0, bit=0x80; bit; bit>>=1){
if(GetBit(0)) byte1 |= bit;
if(GetBit(1)) byte2 |= bit;
}
*(out++)=byte1;
if(!--len) return;
*(out++)=byte2;
if(!--len) return;
}
break;
case 1:
i=plane=0;
while(1) {
for(byte1=byte2=0, bit=0x80; bit; bit>>=1){
if(GetBit(plane)) byte1 |= bit;
if(GetBit(plane+1)) byte2 |= bit;
}
*(out++)=byte1;
if(!--len) return;
*(out++)=byte2;
if(!--len) return;
if(!(i+=32)) plane = (plane+2)&7;
}
break;
case 2:
i=plane=0;
while(1) {
for(byte1=byte2=0, bit=0x80; bit; bit>>=1){
if(GetBit(plane)) byte1 |= bit;
if(GetBit(plane+1)) byte2 |= bit;
}
*(out++)=byte1;
if(!--len) return;
*(out++)=byte2;
if(!--len) return;
if(!(i+=32)) plane ^= 2;
}
break;
case 3:
do {
for(byte1=plane=0, bit=1; bit; bit<<=1, plane++){
if(GetBit(plane)) byte1 |= bit;
}
*(out++)=byte1;
} while(--len);
break;
}
}
#if 0
static uint8 cur_plane;
static uint8 num_bits;
static uint8 next_byte;
void SDD1_init(uint8 *in){
bitplane_type=in[0]>>6;
switch(in[0]&0x30){
case 0x00:
high_context_bits=0x01c0;
low_context_bits =0x0001;
break;
case 0x10:
high_context_bits=0x0180;
low_context_bits =0x0001;
break;
case 0x20:
high_context_bits=0x00c0;
low_context_bits =0x0001;
break;
case 0x30:
high_context_bits=0x0180;
low_context_bits =0x0003;
break;
}
in_stream=(in[0]<<11) | (in[1]<<3);
valid_bits=5;
in_buf=in+2;
memset(bit_ctr, 0, sizeof(bit_ctr));
memset(context_states, 0, sizeof(context_states));
memset(context_MPS, 0, sizeof(context_MPS));
memset(prev_bits, 0, sizeof(prev_bits));
cur_plane=0;
num_bits=0;
}
uint8 SDD1_get_byte(void){
uint8 bit;
uint8 byte=0;
switch(bitplane_type){
case 0:
num_bits+=16;
if(num_bits&16){
next_byte=0;
for(bit=0x80; bit; bit>>=1){
if(GetBit(0)) byte |= bit;
if(GetBit(1)) next_byte |= bit;
}
return byte;
} else {
return next_byte;
}
case 1:
num_bits+=16;
if(num_bits&16){
next_byte=0;
for(bit=0x80; bit; bit>>=1){
if(GetBit(cur_plane)) byte |= bit;
if(GetBit(cur_plane+1)) next_byte |= bit;
}
return byte;
} else {
if(!num_bits) cur_plane = (cur_plane+2)&7;
return next_byte;
}
case 2:
num_bits+=16;
if(num_bits&16){
next_byte=0;
for(bit=0x80; bit; bit>>=1){
if(GetBit(cur_plane)) byte |= bit;
if(GetBit(cur_plane+1)) next_byte |= bit;
}
return byte;
} else {
if(!num_bits) cur_plane ^= 2;
return next_byte;
}
case 3:
for(cur_plane=0, bit=1; bit; bit<<=1, cur_plane++){
if(GetBit(cur_plane)) byte |= bit;
}
return byte;
default:
/* should never happen */
return 0;
}
}
#endif