1 // Highly accurate SNES SPC-700 DSP emulator
2
3 // snes_spc 0.9.0
4 #ifndef SPC_DSP_H
5 #define SPC_DSP_H
6
7 #include "blargg_common.h"
8
9 extern "C" { typedef void (*dsp_copy_func_t)( unsigned char** io, void* state, size_t ); }
10
11 namespace SuperFamicom {
12 class SPC_DSP {
13 public:
14 typedef BOOST::uint8_t uint8_t;
15
16 // Setup
17
18 // Initializes DSP and has it use the 64K RAM provided
19 void init( void* ram_64k );
20
21 // Sets destination for output samples. If out is NULL or out_size is 0,
22 // doesn't generate any.
23 typedef short sample_t;
24 void set_output( sample_t* out, int out_size );
25 sample_t* get_output();
26
27 // Number of samples written to output since it was last set, always
28 // a multiple of 2. Undefined if more samples were generated than
29 // output buffer could hold.
30 int sample_count() const;
31
32 // Emulation
33
34 // Resets DSP to power-on state
35 void reset();
36
37 // Emulates pressing reset switch on SNES
38 void soft_reset();
39
40 // Reads/writes DSP registers. For accuracy, you must first call run()
41 // to catch the DSP up to present.
42 int read ( int addr ) const;
43 void write( int addr, int data );
44
45 // Runs DSP for specified number of clocks (~1024000 per second). Every 32 clocks
46 // a pair of samples is be generated.
47 void run( int clock_count );
48
49 // Sound control
50
51 // Mutes voices corresponding to non-zero bits in mask (issues repeated KOFF events).
52 // Reduces emulation accuracy.
53 enum { voice_count = 8 };
54 void mute_voices( int mask );
55
56 // State
57
58 // Resets DSP and uses supplied values to initialize registers
59 enum { register_count = 128 };
60 void load( uint8_t const regs [register_count] );
61
62 // Saves/loads exact emulator state
63 enum { state_size = 640 }; // maximum space needed when saving
64 typedef dsp_copy_func_t copy_func_t;
65 void copy_state( unsigned char** io, copy_func_t );
66
67 // Returns non-zero if new key-on events occurred since last call
68 bool check_kon();
69
70 // DSP register addresses
71
72 // Global registers
73 enum {
74 r_mvoll = 0x0C, r_mvolr = 0x1C,
75 r_evoll = 0x2C, r_evolr = 0x3C,
76 r_kon = 0x4C, r_koff = 0x5C,
77 r_flg = 0x6C, r_endx = 0x7C,
78 r_efb = 0x0D, r_pmon = 0x2D,
79 r_non = 0x3D, r_eon = 0x4D,
80 r_dir = 0x5D, r_esa = 0x6D,
81 r_edl = 0x7D,
82 r_fir = 0x0F // 8 coefficients at 0x0F, 0x1F ... 0x7F
83 };
84
85 // Voice registers
86 enum {
87 v_voll = 0x00, v_volr = 0x01,
88 v_pitchl = 0x02, v_pitchh = 0x03,
89 v_srcn = 0x04, v_adsr0 = 0x05,
90 v_adsr1 = 0x06, v_gain = 0x07,
91 v_envx = 0x08, v_outx = 0x09
92 };
93
94 public:
out_pos()95 sample_t const* out_pos() const { return m.out; }
96 void disable_surround( bool disable = true );
97 void interpolation_level( int level = 0 ) { m.interpolation_level = level; }
98 public:
99 BLARGG_DISABLE_NOTHROW
100
101 typedef BOOST::int8_t int8_t;
102 typedef BOOST::int16_t int16_t;
103
104 enum { echo_hist_size = 8 };
105
106 enum env_mode_t { env_release, env_attack, env_decay, env_sustain };
107 enum { brr_buf_size = 12 };
108 struct voice_t
109 {
110 int buf [brr_buf_size*2];// decoded samples (twice the size to simplify wrap handling)
111 int buf_pos; // place in buffer where next samples will be decoded
112 int interp_pos; // relative fractional position in sample (0x1000 = 1.0)
113 int brr_addr; // address of current BRR block
114 int brr_offset; // current decoding offset in BRR block
115 uint8_t* regs; // pointer to voice's DSP registers
116 int vbit; // bitmask for voice: 0x01 for voice 0, 0x02 for voice 1, etc.
117 int kon_delay; // KON delay/current setup phase
118 env_mode_t env_mode;
119 int env; // current envelope level
120 int hidden_env; // used by GAIN mode 7, very obscure quirk
121 uint8_t t_envx_out;
122 };
123 //private:
124 enum { brr_block_size = 9 };
125
126 struct state_t
127 {
128 uint8_t regs [register_count];
129
130 // Echo history keeps most recent 8 samples (twice the size to simplify wrap handling)
131 int echo_hist [echo_hist_size * 2] [2];
132 int (*echo_hist_pos) [2]; // &echo_hist [0 to 7]
133
134 int every_other_sample; // toggles every sample
135 int kon; // KON value when last checked
136 int noise;
137 int counter;
138 int echo_offset; // offset from ESA in echo buffer
139 int echo_length; // number of bytes that echo_offset will stop at
140 int phase; // next clock cycle to run (0-31)
141 bool kon_check; // set when a new KON occurs
142
143 // Hidden registers also written to when main register is written to
144 int new_kon;
145 uint8_t endx_buf;
146 uint8_t envx_buf;
147 uint8_t outx_buf;
148
149 // Temporary state between clocks
150
151 // read once per sample
152 int t_pmon;
153 int t_non;
154 int t_eon;
155 int t_dir;
156 int t_koff;
157
158 // read a few clocks ahead then used
159 int t_brr_next_addr;
160 int t_adsr0;
161 int t_brr_header;
162 int t_brr_byte;
163 int t_srcn;
164 int t_esa;
165 int t_echo_enabled;
166
167 // internal state that is recalculated every sample
168 int t_dir_addr;
169 int t_pitch;
170 int t_output;
171 int t_looped;
172 int t_echo_ptr;
173
174 // left/right sums
175 int t_main_out [2];
176 int t_echo_out [2];
177 int t_echo_in [2];
178
179 voice_t voices [voice_count];
180
181 // non-emulation state
182 uint8_t* ram; // 64K shared RAM between DSP and SMP
183 int mute_mask;
184 int surround_threshold;
185 int interpolation_level;
186 sample_t* out;
187 sample_t* out_end;
188 sample_t* out_begin;
189
190 int max_level[voice_count][2];
191 };
192 state_t m;
193
194 void init_counter();
195 void run_counters();
196 unsigned read_counter( int rate );
197
198 int interpolate( voice_t const* v );
199 int interpolate_cubic( voice_t const* v );
200 int interpolate_sinc( voice_t const* v );
201 int interpolate_linear( voice_t const* v );
202 int interpolate_nearest( voice_t const* v );
203
204 void run_envelope( voice_t* const v );
205 void decode_brr( voice_t* v );
206
207 void misc_27();
208 void misc_28();
209 void misc_29();
210 void misc_30();
211
212 void voice_output( voice_t const* v, int ch );
213 void voice_V1( voice_t* const );
214 void voice_V2( voice_t* const );
215 void voice_V3( voice_t* const );
216 void voice_V3a( voice_t* const );
217 void voice_V3b( voice_t* const );
218 void voice_V3c( voice_t* const );
219 void voice_V4( voice_t* const );
220 void voice_V5( voice_t* const );
221 void voice_V6( voice_t* const );
222 void voice_V7( voice_t* const );
223 void voice_V8( voice_t* const );
224 void voice_V9( voice_t* const );
225 void voice_V7_V4_V1( voice_t* const );
226 void voice_V8_V5_V2( voice_t* const );
227 void voice_V9_V6_V3( voice_t* const );
228
229 void echo_read( int ch );
230 int echo_output( int ch );
231 void echo_write( int ch );
232 void echo_22();
233 void echo_23();
234 void echo_24();
235 void echo_25();
236 void echo_26();
237 void echo_27();
238 void echo_28();
239 void echo_29();
240 void echo_30();
241
242 void soft_reset_common();
243
244 public:
mute()245 bool mute() { return m.regs[r_flg] & 0x40; }
246 };
247
248 #include <assert.h>
249
sample_count()250 inline int SPC_DSP::sample_count() const { return m.out - m.out_begin; }
251
read(int addr)252 inline int SPC_DSP::read( int addr ) const
253 {
254 assert( (unsigned) addr < register_count );
255 return m.regs [addr];
256 }
257
write(int addr,int data)258 inline void SPC_DSP::write( int addr, int data )
259 {
260 assert( (unsigned) addr < register_count );
261
262 m.regs [addr] = (uint8_t) data;
263 switch ( addr & 0x0F )
264 {
265 case v_envx:
266 m.envx_buf = (uint8_t) data;
267 break;
268
269 case v_outx:
270 m.outx_buf = (uint8_t) data;
271 break;
272
273 case 0x0C:
274 if ( addr == r_kon )
275 m.new_kon = (uint8_t) data;
276
277 if ( addr == r_endx ) // always cleared, regardless of data written
278 {
279 m.endx_buf = 0;
280 m.regs [r_endx] = 0;
281 }
282 break;
283 }
284 }
285
mute_voices(int mask)286 inline void SPC_DSP::mute_voices( int mask ) { m.mute_mask = mask; }
287
disable_surround(bool disable)288 inline void SPC_DSP::disable_surround( bool disable )
289 {
290 m.surround_threshold = disable ? 0 : -0x4000;
291 }
292
check_kon()293 inline bool SPC_DSP::check_kon()
294 {
295 bool old = m.kon_check;
296 m.kon_check = 0;
297 return old;
298 }
299
get_output()300 inline SPC_DSP::sample_t* SPC_DSP::get_output()
301 {
302 return m.out_begin;
303 }
304
305 #if !SPC_NO_COPY_STATE_FUNCS
306
307 class SPC_State_Copier {
308 SPC_DSP::copy_func_t func;
309 unsigned char** buf;
310 public:
SPC_State_Copier(unsigned char ** p,SPC_DSP::copy_func_t f)311 SPC_State_Copier( unsigned char** p, SPC_DSP::copy_func_t f ) { func = f; buf = p; }
312 void copy( void* state, size_t size );
313 int copy_int( int state, int size );
314 void skip( int count );
315 void extra();
316 };
317
318 #define SPC_COPY( type, state )\
319 {\
320 state = (BOOST::type) copier.copy_int( state, sizeof (BOOST::type) );\
321 assert( (BOOST::type) state == state );\
322 }
323
324 #endif
325
326 };
327
328 #endif
329