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Vgm_Emu_Impl.cpp
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Vgm_Emu_Impl.cpp
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// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
#include "Vgm_Emu.h"
#include <math.h>
#include <string.h>
#include "blargg_endian.h"
/* Copyright (C) 2003-2006 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"
enum {
cmd_gg_stereo = 0x4F,
cmd_psg = 0x50,
cmd_ym2413 = 0x51,
cmd_ym2612_port0 = 0x52,
cmd_ym2612_port1 = 0x53,
cmd_ym2151 = 0x54,
cmd_delay = 0x61,
cmd_delay_735 = 0x62,
cmd_delay_882 = 0x63,
cmd_byte_delay = 0x64,
cmd_end = 0x66,
cmd_data_block = 0x67,
cmd_short_delay = 0x70,
cmd_pcm_delay = 0x80,
cmd_pcm_seek = 0xE0,
pcm_block_type = 0x00,
ym2612_dac_port = 0x2A
};
inline int command_len( int command )
{
switch ( command >> 4 )
{
case 0x03:
case 0x04:
return 2;
case 0x05:
case 0x0A:
case 0x0B:
return 3;
case 0x0C:
case 0x0D:
return 4;
case 0x0E:
case 0x0F:
return 5;
}
check( false );
return 1;
}
template<class Emu>
inline void Ym_Emu<Emu>::begin_frame( short* p )
{
require( enabled() );
out = p;
last_time = 0;
}
template<class Emu>
inline int Ym_Emu<Emu>::run_until( int time )
{
int count = time - last_time;
if ( count > 0 )
{
if ( last_time < 0 )
return false;
last_time = time;
short* p = out;
out += count * Emu::out_chan_count;
Emu::run( count, p );
}
return true;
}
inline Vgm_Emu_Impl::fm_time_t Vgm_Emu_Impl::to_fm_time( vgm_time_t t ) const
{
return (t * fm_time_factor + fm_time_offset) >> fm_time_bits;
}
inline blip_time_t Vgm_Emu_Impl::to_blip_time( vgm_time_t t ) const
{
return (t * blip_time_factor) >> blip_time_bits;
}
void Vgm_Emu_Impl::write_pcm( vgm_time_t vgm_time, int amp )
{
blip_time_t blip_time = to_blip_time( vgm_time );
int old = dac_amp;
int delta = amp - old;
dac_amp = amp;
if ( old >= 0 )
dac_synth.offset_inline( blip_time, delta, &blip_buf );
else
dac_amp |= dac_disabled;
}
blip_time_t Vgm_Emu_Impl::run_commands( vgm_time_t end_time )
{
vgm_time_t vgm_time = this->vgm_time;
byte const* pos = this->pos;
if ( pos >= data_end )
{
set_track_ended();
if ( pos > data_end )
set_warning( "Stream lacked end event" );
}
while ( vgm_time < end_time && pos < data_end )
{
// TODO: be sure there are enough bytes left in stream for particular command
// so we don't read past end
switch ( *pos++ )
{
case cmd_end:
pos = loop_begin; // if not looped, loop_begin == data_end
break;
case cmd_delay_735:
vgm_time += 735;
break;
case cmd_delay_882:
vgm_time += 882;
break;
case cmd_gg_stereo:
psg.write_ggstereo( to_blip_time( vgm_time ), *pos++ );
break;
case cmd_psg:
psg.write_data( to_blip_time( vgm_time ), *pos++ );
break;
case cmd_delay:
vgm_time += pos [1] * 0x100L + pos [0];
pos += 2;
break;
case cmd_byte_delay:
vgm_time += *pos++;
break;
case cmd_ym2413:
if ( ym2413.run_until( to_fm_time( vgm_time ) ) )
ym2413.write( pos [0], pos [1] );
pos += 2;
break;
case cmd_ym2612_port0:
if ( pos [0] == ym2612_dac_port )
{
write_pcm( vgm_time, pos [1] );
}
else if ( ym2612.run_until( to_fm_time( vgm_time ) ) )
{
if ( pos [0] == 0x2B )
{
dac_disabled = (pos [1] >> 7 & 1) - 1;
dac_amp |= dac_disabled;
}
ym2612.write0( pos [0], pos [1] );
}
pos += 2;
break;
case cmd_ym2612_port1:
if ( ym2612.run_until( to_fm_time( vgm_time ) ) )
ym2612.write1( pos [0], pos [1] );
pos += 2;
break;
case cmd_data_block: {
check( *pos == cmd_end );
int type = pos [1];
long size = get_le32( pos + 2 );
pos += 6;
if ( type == pcm_block_type )
pcm_data = pos;
pos += size;
break;
}
case cmd_pcm_seek:
pcm_pos = pcm_data + pos [3] * 0x1000000L + pos [2] * 0x10000L +
pos [1] * 0x100L + pos [0];
pos += 4;
break;
default:
int cmd = pos [-1];
switch ( cmd & 0xF0 )
{
case cmd_pcm_delay:
write_pcm( vgm_time, *pcm_pos++ );
vgm_time += cmd & 0x0F;
break;
case cmd_short_delay:
vgm_time += (cmd & 0x0F) + 1;
break;
case 0x50:
pos += 2;
break;
default:
pos += command_len( cmd ) - 1;
set_warning( "Unknown stream event" );
}
}
}
vgm_time -= end_time;
this->pos = pos;
this->vgm_time = vgm_time;
return to_blip_time( end_time );
}
int Vgm_Emu_Impl::play_frame( blip_time_t blip_time, int sample_count, sample_t* buf )
{
// to do: timing is working mostly by luck
int min_pairs = sample_count >> 1;
int vgm_time = ((long) min_pairs << fm_time_bits) / fm_time_factor - 1;
assert( to_fm_time( vgm_time ) <= min_pairs );
int pairs = min_pairs;
while ( (pairs = to_fm_time( vgm_time )) < min_pairs )
vgm_time++;
//debug_printf( "pairs: %d, min_pairs: %d\n", pairs, min_pairs );
if ( ym2612.enabled() )
{
ym2612.begin_frame( buf );
memset( buf, 0, pairs * stereo * sizeof *buf );
}
else if ( ym2413.enabled() )
{
ym2413.begin_frame( buf );
}
run_commands( vgm_time );
ym2612.run_until( pairs );
ym2413.run_until( pairs );
fm_time_offset = (vgm_time * fm_time_factor + fm_time_offset) -
((long) pairs << fm_time_bits);
psg.end_frame( blip_time );
return pairs * stereo;
}
// Update pre-1.10 header FM rates by scanning commands
void Vgm_Emu_Impl::update_fm_rates( long* ym2413_rate, long* ym2612_rate ) const
{
byte const* p = data + 0x40;
while ( p < data_end )
{
switch ( *p )
{
case cmd_end:
return;
case cmd_psg:
case cmd_byte_delay:
p += 2;
break;
case cmd_delay:
p += 3;
break;
case cmd_data_block:
p += 7 + get_le32( p + 3 );
break;
case cmd_ym2413:
*ym2612_rate = 0;
return;
case cmd_ym2612_port0:
case cmd_ym2612_port1:
*ym2612_rate = *ym2413_rate;
*ym2413_rate = 0;
return;
case cmd_ym2151:
*ym2413_rate = 0;
*ym2612_rate = 0;
return;
default:
p += command_len( *p );
}
}
}

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