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comparison fast_dsp/SPC_DSP.h @ 0:e38dacceb958

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initial import
author Robert McIntyre <rlm@mit.edu>
date Fri, 21 Oct 2011 05:53:11 -0700
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-1:000000000000 0:e38dacceb958
1 // Fast SNES SPC-700 DSP emulator (about 3x speed of accurate one)
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 class SPC_DSP {
10 public:
11 typedef BOOST::uint8_t uint8_t;
12
13 // Setup
14
15 // Initializes DSP and has it use the 64K RAM provided
16 void init( void* ram_64k );
17
18 // Sets destination for output samples. If out is NULL or out_size is 0,
19 // doesn't generate any.
20 typedef short sample_t;
21 void set_output( sample_t* out, int out_size );
22
23 // Number of samples written to output since it was last set, always
24 // a multiple of 2. Undefined if more samples were generated than
25 // output buffer could hold.
26 int sample_count() const;
27
28 // Emulation
29
30 // Resets DSP to power-on state
31 void reset();
32
33 // Emulates pressing reset switch on SNES
34 void soft_reset();
35
36 // Reads/writes DSP registers. For accuracy, you must first call spc_run_dsp()
37 // to catch the DSP up to present.
38 int read ( int addr ) const;
39 void write( int addr, int data );
40
41 // Runs DSP for specified number of clocks (~1024000 per second). Every 32 clocks
42 // a pair of samples is be generated.
43 void run( int clock_count );
44
45 // Sound control
46
47 // Mutes voices corresponding to non-zero bits in mask (overrides VxVOL with 0).
48 // Reduces emulation accuracy.
49 enum { voice_count = 8 };
50 void mute_voices( int mask );
51
52 // If true, prevents channels and global volumes from being phase-negated
53 void disable_surround( bool disable = true );
54
55 // State
56
57 // Resets DSP and uses supplied values to initialize registers
58 enum { register_count = 128 };
59 void load( uint8_t const regs [register_count] );
60
61 // DSP register addresses
62
63 // Global registers
64 enum {
65 r_mvoll = 0x0C, r_mvolr = 0x1C,
66 r_evoll = 0x2C, r_evolr = 0x3C,
67 r_kon = 0x4C, r_koff = 0x5C,
68 r_flg = 0x6C, r_endx = 0x7C,
69 r_efb = 0x0D, r_pmon = 0x2D,
70 r_non = 0x3D, r_eon = 0x4D,
71 r_dir = 0x5D, r_esa = 0x6D,
72 r_edl = 0x7D,
73 r_fir = 0x0F // 8 coefficients at 0x0F, 0x1F ... 0x7F
74 };
75
76 // Voice registers
77 enum {
78 v_voll = 0x00, v_volr = 0x01,
79 v_pitchl = 0x02, v_pitchh = 0x03,
80 v_srcn = 0x04, v_adsr0 = 0x05,
81 v_adsr1 = 0x06, v_gain = 0x07,
82 v_envx = 0x08, v_outx = 0x09
83 };
84
85 public:
86 enum { extra_size = 16 };
87 sample_t* extra() { return m.extra; }
88 sample_t const* out_pos() const { return m.out; }
89 public:
90 BLARGG_DISABLE_NOTHROW
91
92 typedef BOOST::int8_t int8_t;
93 typedef BOOST::int16_t int16_t;
94
95 enum { echo_hist_size = 8 };
96
97 enum env_mode_t { env_release, env_attack, env_decay, env_sustain };
98 enum { brr_buf_size = 12 };
99 struct voice_t
100 {
101 int buf [brr_buf_size*2];// decoded samples (twice the size to simplify wrap handling)
102 int* buf_pos; // place in buffer where next samples will be decoded
103 int interp_pos; // relative fractional position in sample (0x1000 = 1.0)
104 int brr_addr; // address of current BRR block
105 int brr_offset; // current decoding offset in BRR block
106 int kon_delay; // KON delay/current setup phase
107 env_mode_t env_mode;
108 int env; // current envelope level
109 int hidden_env; // used by GAIN mode 7, very obscure quirk
110 int volume [2]; // copy of volume from DSP registers, with surround disabled
111 int enabled; // -1 if enabled, 0 if muted
112 };
113 private:
114 struct state_t
115 {
116 uint8_t regs [register_count];
117
118 // Echo history keeps most recent 8 samples (twice the size to simplify wrap handling)
119 int echo_hist [echo_hist_size * 2] [2];
120 int (*echo_hist_pos) [2]; // &echo_hist [0 to 7]
121
122 int every_other_sample; // toggles every sample
123 int kon; // KON value when last checked
124 int noise;
125 int echo_offset; // offset from ESA in echo buffer
126 int echo_length; // number of bytes that echo_offset will stop at
127 int phase; // next clock cycle to run (0-31)
128 unsigned counters [4];
129
130 int new_kon;
131 int t_koff;
132
133 voice_t voices [voice_count];
134
135 unsigned* counter_select [32];
136
137 // non-emulation state
138 uint8_t* ram; // 64K shared RAM between DSP and SMP
139 int mute_mask;
140 int surround_threshold;
141 sample_t* out;
142 sample_t* out_end;
143 sample_t* out_begin;
144 sample_t extra [extra_size];
145 };
146 state_t m;
147
148 void init_counter();
149 void run_counter( int );
150 void soft_reset_common();
151 void write_outline( int addr, int data );
152 void update_voice_vol( int addr );
153 };
154
155 #include <assert.h>
156
157 inline int SPC_DSP::sample_count() const { return m.out - m.out_begin; }
158
159 inline int SPC_DSP::read( int addr ) const
160 {
161 assert( (unsigned) addr < register_count );
162 return m.regs [addr];
163 }
164
165 inline void SPC_DSP::update_voice_vol( int addr )
166 {
167 int l = (int8_t) m.regs [addr + v_voll];
168 int r = (int8_t) m.regs [addr + v_volr];
169
170 if ( l * r < m.surround_threshold )
171 {
172 // signs differ, so negate those that are negative
173 l ^= l >> 7;
174 r ^= r >> 7;
175 }
176
177 voice_t& v = m.voices [addr >> 4];
178 int enabled = v.enabled;
179 v.volume [0] = l & enabled;
180 v.volume [1] = r & enabled;
181 }
182
183 inline void SPC_DSP::write( int addr, int data )
184 {
185 assert( (unsigned) addr < register_count );
186
187 m.regs [addr] = (uint8_t) data;
188 int low = addr & 0x0F;
189 if ( low < 0x2 ) // voice volumes
190 {
191 update_voice_vol( low ^ addr );
192 }
193 else if ( low == 0xC )
194 {
195 if ( addr == r_kon )
196 m.new_kon = (uint8_t) data;
197
198 if ( addr == r_endx ) // always cleared, regardless of data written
199 m.regs [r_endx] = 0;
200 }
201 }
202
203 inline void SPC_DSP::disable_surround( bool disable )
204 {
205 m.surround_threshold = disable ? 0 : -0x4000;
206 }
207
208 #define SPC_NO_COPY_STATE_FUNCS 1
209
210 #define SPC_LESS_ACCURATE 1
211
212 #endif