mirror of
https://github.com/dborth/snes9xgx.git
synced 2024-12-27 11:41:49 +01:00
334 lines
9.1 KiB
C++
334 lines
9.1 KiB
C++
/*****************************************************************************\
|
|
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
|