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/gme/Snes_Spc.cpp

http://game-music-emu.googlecode.com/
C++ | 380 lines | 269 code | 69 blank | 42 comment | 27 complexity | 499ff690ed23704cdf075f57fa6dc8dd MD5 | raw file
  1// SPC emulation support: init, sample buffering, reset, SPC loading
  2
  3// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
  4
  5#include "Snes_Spc.h"
  6
  7#include <string.h>
  8
  9/* Copyright (C) 2004-2007 Shay Green. This module is free software; you
 10can redistribute it and/or modify it under the terms of the GNU Lesser
 11General Public License as published by the Free Software Foundation; either
 12version 2.1 of the License, or (at your option) any later version. This
 13module is distributed in the hope that it will be useful, but WITHOUT ANY
 14WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 15FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 16details. You should have received a copy of the GNU Lesser General Public
 17License along with this module; if not, write to the Free Software Foundation,
 18Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
 19
 20#include "blargg_source.h"
 21
 22#define RAM         (m.ram.ram)
 23#define REGS        (m.smp_regs [0])
 24#define REGS_IN     (m.smp_regs [1])
 25
 26// (n ? n : 256)
 27#define IF_0_THEN_256( n ) ((uint8_t) ((n) - 1) + 1)
 28
 29
 30//// Init
 31
 32blargg_err_t Snes_Spc::init()
 33{
 34	memset( &m, 0, sizeof m );
 35	dsp.init( RAM );
 36	
 37	m.tempo = tempo_unit;
 38	
 39	// Most SPC music doesn't need ROM, and almost all the rest only rely
 40	// on these two bytes
 41	m.rom [0x3E] = 0xFF;
 42	m.rom [0x3F] = 0xC0;
 43	
 44	static unsigned char const cycle_table [128] =
 45	{//   01   23   45   67   89   AB   CD   EF
 46	    0x28,0x47,0x34,0x36,0x26,0x54,0x54,0x68, // 0
 47	    0x48,0x47,0x45,0x56,0x55,0x65,0x22,0x46, // 1
 48	    0x28,0x47,0x34,0x36,0x26,0x54,0x54,0x74, // 2
 49	    0x48,0x47,0x45,0x56,0x55,0x65,0x22,0x38, // 3
 50	    0x28,0x47,0x34,0x36,0x26,0x44,0x54,0x66, // 4
 51	    0x48,0x47,0x45,0x56,0x55,0x45,0x22,0x43, // 5
 52	    0x28,0x47,0x34,0x36,0x26,0x44,0x54,0x75, // 6
 53	    0x48,0x47,0x45,0x56,0x55,0x55,0x22,0x36, // 7
 54	    0x28,0x47,0x34,0x36,0x26,0x54,0x52,0x45, // 8
 55	    0x48,0x47,0x45,0x56,0x55,0x55,0x22,0xC5, // 9
 56	    0x38,0x47,0x34,0x36,0x26,0x44,0x52,0x44, // A
 57	    0x48,0x47,0x45,0x56,0x55,0x55,0x22,0x34, // B
 58	    0x38,0x47,0x45,0x47,0x25,0x64,0x52,0x49, // C
 59	    0x48,0x47,0x56,0x67,0x45,0x55,0x22,0x83, // D
 60	    0x28,0x47,0x34,0x36,0x24,0x53,0x43,0x40, // E
 61	    0x48,0x47,0x45,0x56,0x34,0x54,0x22,0x60, // F
 62	};
 63	
 64	// unpack cycle table
 65	for ( int i = 0; i < 128; i++ )
 66	{
 67		int n = cycle_table [i];
 68		m.cycle_table [i * 2 + 0] = n >> 4;
 69		m.cycle_table [i * 2 + 1] = n & 0x0F;
 70	}
 71	
 72	#if SPC_LESS_ACCURATE
 73		memcpy( reg_times, reg_times_, sizeof reg_times );
 74	#endif
 75	
 76	reset();
 77	return 0;
 78}
 79
 80void Snes_Spc::init_rom( uint8_t const in [rom_size] )
 81{
 82	memcpy( m.rom, in, sizeof m.rom );
 83}
 84
 85void Snes_Spc::set_tempo( int t )
 86{
 87	m.tempo = t;
 88	int const timer2_shift = 4; // 64 kHz
 89	int const other_shift  = 3; //  8 kHz
 90	
 91	#if SPC_DISABLE_TEMPO
 92		m.timers [2].prescaler = timer2_shift;
 93		m.timers [1].prescaler = timer2_shift + other_shift;
 94		m.timers [0].prescaler = timer2_shift + other_shift;
 95	#else
 96		if ( !t )
 97			t = 1;
 98		int const timer2_rate  = 1 << timer2_shift;
 99		int rate = (timer2_rate * tempo_unit + (t >> 1)) / t;
100		if ( rate < timer2_rate / 4 )
101			rate = timer2_rate / 4; // max 4x tempo
102		m.timers [2].prescaler = rate;
103		m.timers [1].prescaler = rate << other_shift;
104		m.timers [0].prescaler = rate << other_shift;
105	#endif
106}
107
108// Timer registers have been loaded. Applies these to the timers. Does not
109// reset timer prescalers or dividers.
110void Snes_Spc::timers_loaded()
111{
112	int i;
113	for ( i = 0; i < timer_count; i++ )
114	{
115		Timer* t = &m.timers [i];
116		t->period  = IF_0_THEN_256( REGS [r_t0target + i] );
117		t->enabled = REGS [r_control] >> i & 1;
118		t->counter = REGS_IN [r_t0out + i] & 0x0F;
119	}
120	
121	set_tempo( m.tempo );
122}
123
124// Loads registers from unified 16-byte format
125void Snes_Spc::load_regs( uint8_t const in [reg_count] )
126{
127	memcpy( REGS, in, reg_count );
128	memcpy( REGS_IN, REGS, reg_count );
129	
130	// These always read back as 0
131	REGS_IN [r_test    ] = 0;
132	REGS_IN [r_control ] = 0;
133	REGS_IN [r_t0target] = 0;
134	REGS_IN [r_t1target] = 0;
135	REGS_IN [r_t2target] = 0;
136}
137
138// RAM was just loaded from SPC, with $F0-$FF containing SMP registers
139// and timer counts. Copies these to proper registers.
140void Snes_Spc::ram_loaded()
141{
142	m.rom_enabled = 0;
143	load_regs( &RAM [0xF0] );
144	
145	// Put STOP instruction around memory to catch PC underflow/overflow
146	memset( m.ram.padding1, cpu_pad_fill, sizeof m.ram.padding1 );
147	memset( m.ram.padding2, cpu_pad_fill, sizeof m.ram.padding2 );
148}
149
150// Registers were just loaded. Applies these new values.
151void Snes_Spc::regs_loaded()
152{
153	enable_rom( REGS [r_control] & 0x80 );
154	timers_loaded();
155}
156
157void Snes_Spc::reset_time_regs()
158{
159	m.cpu_error     = 0;
160	m.echo_accessed = 0;
161	m.spc_time      = 0;
162	m.dsp_time      = 0;
163	#if SPC_LESS_ACCURATE
164		m.dsp_time = clocks_per_sample + 1;
165	#endif
166	
167	for ( int i = 0; i < timer_count; i++ )
168	{
169		Timer* t = &m.timers [i];
170		t->next_time = 1;
171		t->divider   = 0;
172	}
173	
174	regs_loaded();
175	
176	m.extra_clocks = 0;
177	reset_buf();
178}
179
180void Snes_Spc::reset_common( int timer_counter_init )
181{
182	int i;
183	for ( i = 0; i < timer_count; i++ )
184		REGS_IN [r_t0out + i] = timer_counter_init;
185	
186	// Run IPL ROM
187	memset( &m.cpu_regs, 0, sizeof m.cpu_regs );
188	m.cpu_regs.pc = rom_addr;
189	
190	REGS [r_test   ] = 0x0A;
191	REGS [r_control] = 0xB0; // ROM enabled, clear ports
192	for ( i = 0; i < port_count; i++ )
193		REGS_IN [r_cpuio0 + i] = 0;
194	
195	reset_time_regs();
196}
197
198void Snes_Spc::soft_reset()
199{
200	reset_common( 0 );
201	dsp.soft_reset();
202}
203
204void Snes_Spc::reset()
205{
206	memset( RAM, 0xFF, 0x10000 );
207	ram_loaded();
208	reset_common( 0x0F );
209	dsp.reset();
210}
211
212char const Snes_Spc::signature [signature_size + 1] =
213		"SNES-SPC700 Sound File Data v0.30\x1A\x1A";
214
215blargg_err_t Snes_Spc::load_spc( void const* data, long size )
216{
217	spc_file_t const* const spc = (spc_file_t const*) data;
218	
219	// be sure compiler didn't insert any padding into fle_t
220	assert( sizeof (spc_file_t) == spc_min_file_size + 0x80 );
221	
222	// Check signature and file size
223	if ( size < signature_size || memcmp( spc, signature, 27 ) )
224		return "Not an SPC file";
225	
226	if ( size < spc_min_file_size )
227		return "Corrupt SPC file";
228	
229	// CPU registers
230	m.cpu_regs.pc  = spc->pch * 0x100 + spc->pcl;
231	m.cpu_regs.a   = spc->a;
232	m.cpu_regs.x   = spc->x;
233	m.cpu_regs.y   = spc->y;
234	m.cpu_regs.psw = spc->psw;
235	m.cpu_regs.sp  = spc->sp;
236	
237	// RAM and registers
238	memcpy( RAM, spc->ram, 0x10000 );
239	ram_loaded();
240	
241	// DSP registers
242	dsp.load( spc->dsp );
243	
244	reset_time_regs();
245	
246	return 0;
247}
248
249void Snes_Spc::clear_echo()
250{
251	if ( !(dsp.read( Spc_Dsp::r_flg ) & 0x20) )
252	{
253		int addr = 0x100 * dsp.read( Spc_Dsp::r_esa );
254		int end  = addr + 0x800 * (dsp.read( Spc_Dsp::r_edl ) & 0x0F);
255		if ( end > 0x10000 )
256			end = 0x10000;
257		memset( &RAM [addr], 0xFF, end - addr );
258	}
259}
260
261
262//// Sample output
263
264void Snes_Spc::reset_buf()
265{
266	// Start with half extra buffer of silence
267	sample_t* out = m.extra_buf;
268	while ( out < &m.extra_buf [extra_size / 2] )
269		*out++ = 0;
270	
271	m.extra_pos = out;
272	m.buf_begin = 0;
273	
274	dsp.set_output( 0, 0 );
275}
276
277void Snes_Spc::set_output( sample_t* out, int size )
278{
279	require( (size & 1) == 0 ); // size must be even
280	
281	m.extra_clocks &= clocks_per_sample - 1;
282	if ( out )
283	{
284		sample_t const* out_end = out + size;
285		m.buf_begin = out;
286		m.buf_end   = out_end;
287		
288		// Copy extra to output
289		sample_t const* in = m.extra_buf;
290		while ( in < m.extra_pos && out < out_end )
291			*out++ = *in++;
292		
293		// Handle output being full already
294		if ( out >= out_end )
295		{
296			// Have DSP write to remaining extra space
297			out     = dsp.extra();
298			out_end = &dsp.extra() [extra_size];
299			
300			// Copy any remaining extra samples as if DSP wrote them
301			while ( in < m.extra_pos )
302				*out++ = *in++;
303			assert( out <= out_end );
304		}
305		
306		dsp.set_output( out, out_end - out );
307	}
308	else
309	{
310		reset_buf();
311	}
312}
313
314void Snes_Spc::save_extra()
315{
316	// Get end pointers
317	sample_t const* main_end = m.buf_end;     // end of data written to buf
318	sample_t const* dsp_end  = dsp.out_pos(); // end of data written to dsp.extra()
319	if ( m.buf_begin <= dsp_end && dsp_end <= main_end )
320	{
321		main_end = dsp_end;
322		dsp_end  = dsp.extra(); // nothing in DSP's extra
323	}
324	
325	// Copy any extra samples at these ends into extra_buf
326	sample_t* out = m.extra_buf;
327	sample_t const* in;
328	for ( in = m.buf_begin + sample_count(); in < main_end; in++ )
329		*out++ = *in;
330	for ( in = dsp.extra(); in < dsp_end ; in++ )
331		*out++ = *in;
332	
333	m.extra_pos = out;
334	assert( out <= &m.extra_buf [extra_size] );
335}
336
337blargg_err_t Snes_Spc::play( int count, sample_t* out )
338{
339	require( (count & 1) == 0 ); // must be even
340	if ( count )
341	{
342		set_output( out, count );
343		end_frame( count * (clocks_per_sample / 2) );
344	}
345	
346	const char* err = m.cpu_error;
347	m.cpu_error = 0;
348	return err;
349}
350
351blargg_err_t Snes_Spc::skip( int count )
352{
353	#if SPC_LESS_ACCURATE
354	if ( count > 2 * sample_rate * 2 )
355	{
356		set_output( 0, 0 );
357		
358		// Skip a multiple of 4 samples
359		time_t end = count;
360		count = (count & 3) + 1 * sample_rate * 2;
361		end = (end - count) * (clocks_per_sample / 2);
362		
363		m.skipped_kon  = 0;
364		m.skipped_koff = 0;
365		
366		// Preserve DSP and timer synchronization
367		// TODO: verify that this really preserves it
368		int old_dsp_time = m.dsp_time + m.spc_time;
369		m.dsp_time = end - m.spc_time + skipping_time;
370		end_frame( end );
371		m.dsp_time = m.dsp_time - skipping_time + old_dsp_time;
372		
373		dsp.write( Spc_Dsp::r_koff, m.skipped_koff & ~m.skipped_kon );
374		dsp.write( Spc_Dsp::r_kon , m.skipped_kon );
375		clear_echo();
376	}
377	#endif
378	
379	return play( count, 0 );
380}