aboutsummaryrefslogtreecommitdiff
path: root/source/sdd1emu.c
blob: c7005ecee8dd040c5287c77db4804c5e70365ea1 (plain)
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
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
/*******************************************************************************
  Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.

  (c) Copyright 1996 - 2002 Gary Henderson (gary.henderson@ntlworld.com) and
                            Jerremy Koot (jkoot@snes9x.com)

  (c) Copyright 2001 - 2004 John Weidman (jweidman@slip.net)

  (c) Copyright 2002 - 2004 Brad Jorsch (anomie@users.sourceforge.net),
                            funkyass (funkyass@spam.shaw.ca),
                            Joel Yliluoma (http://iki.fi/bisqwit/)
                            Kris Bleakley (codeviolation@hotmail.com),
                            Matthew Kendora,
                            Nach (n-a-c-h@users.sourceforge.net),
                            Peter Bortas (peter@bortas.org) and
                            zones (kasumitokoduck@yahoo.com)

  C4 x86 assembler and some C emulation code
  (c) Copyright 2000 - 2003 zsKnight (zsknight@zsnes.com),
                            _Demo_ (_demo_@zsnes.com), and Nach

  C4 C++ code
  (c) Copyright 2003 Brad Jorsch

  DSP-1 emulator code
  (c) Copyright 1998 - 2004 Ivar (ivar@snes9x.com), _Demo_, Gary Henderson,
                            John Weidman, neviksti (neviksti@hotmail.com),
                            Kris Bleakley, Andreas Naive

  DSP-2 emulator code
  (c) Copyright 2003 Kris Bleakley, John Weidman, neviksti, Matthew Kendora, and
                     Lord Nightmare (lord_nightmare@users.sourceforge.net

  OBC1 emulator code
  (c) Copyright 2001 - 2004 zsKnight, pagefault (pagefault@zsnes.com) and
                            Kris Bleakley
  Ported from x86 assembler to C by sanmaiwashi

  SPC7110 and RTC C++ emulator code
  (c) Copyright 2002 Matthew Kendora with research by
                     zsKnight, John Weidman, and Dark Force

  S-DD1 C emulator code
  (c) Copyright 2003 Brad Jorsch with research by
                     Andreas Naive and John Weidman

  S-RTC C emulator code
  (c) Copyright 2001 John Weidman

  ST010 C++ emulator code
  (c) Copyright 2003 Feather, Kris Bleakley, John Weidman and Matthew Kendora

  Super FX x86 assembler emulator code
  (c) Copyright 1998 - 2003 zsKnight, _Demo_, and pagefault

  Super FX C emulator code
  (c) Copyright 1997 - 1999 Ivar, Gary Henderson and John Weidman


  SH assembler code partly based on x86 assembler code
  (c) Copyright 2002 - 2004 Marcus Comstedt (marcus@mc.pp.se)


  Specific ports contains the works of other authors. See headers in
  individual files.

  Snes9x homepage: http://www.snes9x.com

  Permission to use, copy, modify and distribute Snes9x in both binary and
  source form, for non-commercial purposes, is hereby granted without fee,
  providing that this license information and copyright notice appear with
  all copies and any derived work.

  This software is provided 'as-is', without any express or implied
  warranty. In no event shall the authors be held liable for any damages
  arising from the use of this software.

  Snes9x is freeware for PERSONAL USE only. Commercial users should
  seek permission of the copyright holders first. Commercial use includes
  charging money for Snes9x or software derived from Snes9x.

  The copyright holders request that bug fixes and improvements to the code
  should be forwarded to them so everyone can benefit from the modifications
  in future versions.

  Super NES and Super Nintendo Entertainment System are trademarks of
  Nintendo Co., Limited and its subsidiary companies.
*******************************************************************************/
/* 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 <string.h>
#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;
   }
}

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;
   }
}