/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
- // SPC emulation support: init, sample buffering, reset, SPC loading
- // Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
- #include "Snes_Spc.h"
- #include <string.h>
- /* Copyright (C) 2004-2007 Shay Green. This module is free software; you
- can redistribute it and/or modify it under the terms of the GNU Lesser
- General Public License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version. This
- module is distributed in the hope that it will be useful, but WITHOUT ANY
- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
- details. You should have received a copy of the GNU Lesser General Public
- License along with this module; if not, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
- #include "blargg_source.h"
- #define RAM (m.ram.ram)
- #define REGS (m.smp_regs [0])
- #define REGS_IN (m.smp_regs [1])
- // (n ? n : 256)
- #define IF_0_THEN_256( n ) ((uint8_t) ((n) - 1) + 1)
- //// Init
- blargg_err_t Snes_Spc::init()
- {
- memset( &m, 0, sizeof m );
- dsp.init( RAM );
-
- m.tempo = tempo_unit;
-
- // Most SPC music doesn't need ROM, and almost all the rest only rely
- // on these two bytes
- m.rom [0x3E] = 0xFF;
- m.rom [0x3F] = 0xC0;
-
- static unsigned char const cycle_table [128] =
- {// 01 23 45 67 89 AB CD EF
- 0x28,0x47,0x34,0x36,0x26,0x54,0x54,0x68, // 0
- 0x48,0x47,0x45,0x56,0x55,0x65,0x22,0x46, // 1
- 0x28,0x47,0x34,0x36,0x26,0x54,0x54,0x74, // 2
- 0x48,0x47,0x45,0x56,0x55,0x65,0x22,0x38, // 3
- 0x28,0x47,0x34,0x36,0x26,0x44,0x54,0x66, // 4
- 0x48,0x47,0x45,0x56,0x55,0x45,0x22,0x43, // 5
- 0x28,0x47,0x34,0x36,0x26,0x44,0x54,0x75, // 6
- 0x48,0x47,0x45,0x56,0x55,0x55,0x22,0x36, // 7
- 0x28,0x47,0x34,0x36,0x26,0x54,0x52,0x45, // 8
- 0x48,0x47,0x45,0x56,0x55,0x55,0x22,0xC5, // 9
- 0x38,0x47,0x34,0x36,0x26,0x44,0x52,0x44, // A
- 0x48,0x47,0x45,0x56,0x55,0x55,0x22,0x34, // B
- 0x38,0x47,0x45,0x47,0x25,0x64,0x52,0x49, // C
- 0x48,0x47,0x56,0x67,0x45,0x55,0x22,0x83, // D
- 0x28,0x47,0x34,0x36,0x24,0x53,0x43,0x40, // E
- 0x48,0x47,0x45,0x56,0x34,0x54,0x22,0x60, // F
- };
-
- // unpack cycle table
- for ( int i = 0; i < 128; i++ )
- {
- int n = cycle_table [i];
- m.cycle_table [i * 2 + 0] = n >> 4;
- m.cycle_table [i * 2 + 1] = n & 0x0F;
- }
-
- #if SPC_LESS_ACCURATE
- memcpy( reg_times, reg_times_, sizeof reg_times );
- #endif
-
- reset();
- return 0;
- }
- void Snes_Spc::init_rom( uint8_t const in [rom_size] )
- {
- memcpy( m.rom, in, sizeof m.rom );
- }
- void Snes_Spc::set_tempo( int t )
- {
- m.tempo = t;
- int const timer2_shift = 4; // 64 kHz
- int const other_shift = 3; // 8 kHz
-
- #if SPC_DISABLE_TEMPO
- m.timers [2].prescaler = timer2_shift;
- m.timers [1].prescaler = timer2_shift + other_shift;
- m.timers [0].prescaler = timer2_shift + other_shift;
- #else
- if ( !t )
- t = 1;
- int const timer2_rate = 1 << timer2_shift;
- int rate = (timer2_rate * tempo_unit + (t >> 1)) / t;
- if ( rate < timer2_rate / 4 )
- rate = timer2_rate / 4; // max 4x tempo
- m.timers [2].prescaler = rate;
- m.timers [1].prescaler = rate << other_shift;
- m.timers [0].prescaler = rate << other_shift;
- #endif
- }
- // Timer registers have been loaded. Applies these to the timers. Does not
- // reset timer prescalers or dividers.
- void Snes_Spc::timers_loaded()
- {
- int i;
- for ( i = 0; i < timer_count; i++ )
- {
- Timer* t = &m.timers [i];
- t->period = IF_0_THEN_256( REGS [r_t0target + i] );
- t->enabled = REGS [r_control] >> i & 1;
- t->counter = REGS_IN [r_t0out + i] & 0x0F;
- }
-
- set_tempo( m.tempo );
- }
- // Loads registers from unified 16-byte format
- void Snes_Spc::load_regs( uint8_t const in [reg_count] )
- {
- memcpy( REGS, in, reg_count );
- memcpy( REGS_IN, REGS, reg_count );
-
- // These always read back as 0
- REGS_IN [r_test ] = 0;
- REGS_IN [r_control ] = 0;
- REGS_IN [r_t0target] = 0;
- REGS_IN [r_t1target] = 0;
- REGS_IN [r_t2target] = 0;
- }
- // RAM was just loaded from SPC, with $F0-$FF containing SMP registers
- // and timer counts. Copies these to proper registers.
- void Snes_Spc::ram_loaded()
- {
- m.rom_enabled = 0;
- load_regs( &RAM [0xF0] );
-
- // Put STOP instruction around memory to catch PC underflow/overflow
- memset( m.ram.padding1, cpu_pad_fill, sizeof m.ram.padding1 );
- memset( m.ram.padding2, cpu_pad_fill, sizeof m.ram.padding2 );
- }
- // Registers were just loaded. Applies these new values.
- void Snes_Spc::regs_loaded()
- {
- enable_rom( REGS [r_control] & 0x80 );
- timers_loaded();
- }
- void Snes_Spc::reset_time_regs()
- {
- m.cpu_error = 0;
- m.echo_accessed = 0;
- m.spc_time = 0;
- m.dsp_time = 0;
- #if SPC_LESS_ACCURATE
- m.dsp_time = clocks_per_sample + 1;
- #endif
-
- for ( int i = 0; i < timer_count; i++ )
- {
- Timer* t = &m.timers [i];
- t->next_time = 1;
- t->divider = 0;
- }
-
- regs_loaded();
-
- m.extra_clocks = 0;
- reset_buf();
- }
- void Snes_Spc::reset_common( int timer_counter_init )
- {
- int i;
- for ( i = 0; i < timer_count; i++ )
- REGS_IN [r_t0out + i] = timer_counter_init;
-
- // Run IPL ROM
- memset( &m.cpu_regs, 0, sizeof m.cpu_regs );
- m.cpu_regs.pc = rom_addr;
-
- REGS [r_test ] = 0x0A;
- REGS [r_control] = 0xB0; // ROM enabled, clear ports
- for ( i = 0; i < port_count; i++ )
- REGS_IN [r_cpuio0 + i] = 0;
-
- reset_time_regs();
- }
- void Snes_Spc::soft_reset()
- {
- reset_common( 0 );
- dsp.soft_reset();
- }
- void Snes_Spc::reset()
- {
- memset( RAM, 0xFF, 0x10000 );
- ram_loaded();
- reset_common( 0x0F );
- dsp.reset();
- }
- char const Snes_Spc::signature [signature_size + 1] =
- "SNES-SPC700 Sound File Data v0.30\x1A\x1A";
- blargg_err_t Snes_Spc::load_spc( void const* data, long size )
- {
- spc_file_t const* const spc = (spc_file_t const*) data;
-
- // be sure compiler didn't insert any padding into fle_t
- assert( sizeof (spc_file_t) == spc_min_file_size + 0x80 );
-
- // Check signature and file size
- if ( size < signature_size || memcmp( spc, signature, 27 ) )
- return "Not an SPC file";
-
- if ( size < spc_min_file_size )
- return "Corrupt SPC file";
-
- // CPU registers
- m.cpu_regs.pc = spc->pch * 0x100 + spc->pcl;
- m.cpu_regs.a = spc->a;
- m.cpu_regs.x = spc->x;
- m.cpu_regs.y = spc->y;
- m.cpu_regs.psw = spc->psw;
- m.cpu_regs.sp = spc->sp;
-
- // RAM and registers
- memcpy( RAM, spc->ram, 0x10000 );
- ram_loaded();
-
- // DSP registers
- dsp.load( spc->dsp );
-
- reset_time_regs();
-
- return 0;
- }
- void Snes_Spc::clear_echo()
- {
- if ( !(dsp.read( Spc_Dsp::r_flg ) & 0x20) )
- {
- int addr = 0x100 * dsp.read( Spc_Dsp::r_esa );
- int end = addr + 0x800 * (dsp.read( Spc_Dsp::r_edl ) & 0x0F);
- if ( end > 0x10000 )
- end = 0x10000;
- memset( &RAM [addr], 0xFF, end - addr );
- }
- }
- //// Sample output
- void Snes_Spc::reset_buf()
- {
- // Start with half extra buffer of silence
- sample_t* out = m.extra_buf;
- while ( out < &m.extra_buf [extra_size / 2] )
- *out++ = 0;
-
- m.extra_pos = out;
- m.buf_begin = 0;
-
- dsp.set_output( 0, 0 );
- }
- void Snes_Spc::set_output( sample_t* out, int size )
- {
- require( (size & 1) == 0 ); // size must be even
-
- m.extra_clocks &= clocks_per_sample - 1;
- if ( out )
- {
- sample_t const* out_end = out + size;
- m.buf_begin = out;
- m.buf_end = out_end;
-
- // Copy extra to output
- sample_t const* in = m.extra_buf;
- while ( in < m.extra_pos && out < out_end )
- *out++ = *in++;
-
- // Handle output being full already
- if ( out >= out_end )
- {
- // Have DSP write to remaining extra space
- out = dsp.extra();
- out_end = &dsp.extra() [extra_size];
-
- // Copy any remaining extra samples as if DSP wrote them
- while ( in < m.extra_pos )
- *out++ = *in++;
- assert( out <= out_end );
- }
-
- dsp.set_output( out, out_end - out );
- }
- else
- {
- reset_buf();
- }
- }
- void Snes_Spc::save_extra()
- {
- // Get end pointers
- sample_t const* main_end = m.buf_end; // end of data written to buf
- sample_t const* dsp_end = dsp.out_pos(); // end of data written to dsp.extra()
- if ( m.buf_begin <= dsp_end && dsp_end <= main_end )
- {
- main_end = dsp_end;
- dsp_end = dsp.extra(); // nothing in DSP's extra
- }
-
- // Copy any extra samples at these ends into extra_buf
- sample_t* out = m.extra_buf;
- sample_t const* in;
- for ( in = m.buf_begin + sample_count(); in < main_end; in++ )
- *out++ = *in;
- for ( in = dsp.extra(); in < dsp_end ; in++ )
- *out++ = *in;
-
- m.extra_pos = out;
- assert( out <= &m.extra_buf [extra_size] );
- }
- blargg_err_t Snes_Spc::play( int count, sample_t* out )
- {
- require( (count & 1) == 0 ); // must be even
- if ( count )
- {
- set_output( out, count );
- end_frame( count * (clocks_per_sample / 2) );
- }
-
- const char* err = m.cpu_error;
- m.cpu_error = 0;
- return err;
- }
- blargg_err_t Snes_Spc::skip( int count )
- {
- #if SPC_LESS_ACCURATE
- if ( count > 2 * sample_rate * 2 )
- {
- set_output( 0, 0 );
-
- // Skip a multiple of 4 samples
- time_t end = count;
- count = (count & 3) + 1 * sample_rate * 2;
- end = (end - count) * (clocks_per_sample / 2);
-
- m.skipped_kon = 0;
- m.skipped_koff = 0;
-
- // Preserve DSP and timer synchronization
- // TODO: verify that this really preserves it
- int old_dsp_time = m.dsp_time + m.spc_time;
- m.dsp_time = end - m.spc_time + skipping_time;
- end_frame( end );
- m.dsp_time = m.dsp_time - skipping_time + old_dsp_time;
-
- dsp.write( Spc_Dsp::r_koff, m.skipped_koff & ~m.skipped_kon );
- dsp.write( Spc_Dsp::r_kon , m.skipped_kon );
- clear_echo();
- }
- #endif
-
- return play( count, 0 );
- }