gzdoom/game-music-emu/gme/Snes_Spc.cpp

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// SPC emulation support: init, sample buffering, reset, SPC loading
// snes_spc 0.9.0. 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, int(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 );
}