rockbox/apps/codecs/libgme/vgm_emu.c

1053 lines
27 KiB
C

// Game_Music_Emu 0.5.5. http://www.slack.net/~ant/
#include "vgm_emu.h"
#include "blargg_endian.h"
#include <string.h>
#include <math.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"
const char* const gme_wrong_file_type = "Wrong file type for this emulator";
double const fm_gain = 3.0; // FM emulators are internally quieter to avoid 16-bit overflow
double const rolloff = 0.990;
double const oversample_factor = 1.5;
int const silence_max = 6; // seconds
int const silence_threshold = 0x10;
long const fade_block_size = 512;
int const fade_shift = 8; // fade ends with gain at 1.0 / (1 << fade_shift)
// VGM commands (Spec v1.50)
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,
ym2612_dac_pan_port = 0xB6
};
void clear_track_vars( struct Vgm_Emu* this )
{
this->out_time = 0;
this->emu_time = 0;
this->emu_track_ended_ = true;
this->track_ended = true;
this->fade_start = INT_MAX / 2 + 1;
this->fade_step = 1;
this->silence_time = 0;
this->silence_count = 0;
this->buf_remain = 0;
}
int play_frame( struct Vgm_Emu* this, blip_time_t blip_time, int sample_count, sample_t* buf );
static int play_frame_( void* data, blip_time_t blip_time, int sample_count, short int* buf )
{
return play_frame( (struct Vgm_Emu*) data, blip_time, sample_count, buf );
}
void Vgm_init( struct Vgm_Emu* this )
{
this->sample_rate = 0;
this->mute_mask_ = 0;
this->tempo = 1.0;
// defaults
this->max_initial_silence = 2;
this->silence_lookahead = 1; // tracks should already be trimmed
this->ignore_silence = false;
// Disable oversampling by default
this->disable_oversampling = true;
this->psg_rate = 0;
Sms_apu_init( &this->psg );
Synth_init( &this->pcm );
Buffer_init( &this->buf );
Buffer_init( &this->stereo_buf );
this->blip_buf = &this->stereo_buf.bufs [0];
// Init fm chips
Ym2413_init( &this->ym2413 );
Ym2612_init( &this->ym2612 );
// Init resampler
Resampler_init( &this->resampler );
Resampler_set_callback( &this->resampler, play_frame_, this );
// Set sound gain, a value too high
// will cause saturation
Sound_set_gain(this, 1.0);
// Unload
this->voice_count = 0;
clear_track_vars( this );
}
// Track info
static byte const* skip_gd3_str( byte const* in, byte const* end )
{
while ( end - in >= 2 )
{
in += 2;
if ( !(in [-2] | in [-1]) )
break;
}
return in;
}
static byte const* get_gd3_str( byte const* in, byte const* end, char* field )
{
byte const* mid = skip_gd3_str( in, end );
int i, len = (mid - in) / 2 - 1;
if ( field && len > 0 )
{
len = min( len, (int) gme_max_field );
field [len] = 0;
for ( i = 0; i < len; i++ )
field [i] = (in [i * 2 + 1] ? '?' : in [i * 2]); // TODO: convert to utf-8
}
return mid;
}
static byte const* get_gd3_pair( byte const* in, byte const* end, char* field )
{
return skip_gd3_str( get_gd3_str( in, end, field ), end );
}
static void parse_gd3( byte const* in, byte const* end, struct track_info_t* out )
{
in = get_gd3_pair( in, end, out->song );
in = get_gd3_pair( in, end, out->game );
in = get_gd3_pair( in, end, NULL ); // Skip system
in = get_gd3_pair( in, end, out->author );
}
int const gd3_header_size = 12;
static long check_gd3_header( byte const* h, long remain )
{
if ( remain < gd3_header_size ) return 0;
if ( memcmp( h, "Gd3 ", 4 ) ) return 0;
if ( get_le32( h + 4 ) >= 0x200 ) return 0;
long gd3_size = get_le32( h + 8 );
if ( gd3_size > remain - gd3_header_size )
gd3_size = remain - gd3_header_size;
return gd3_size;
}
byte const* gd3_data( struct Vgm_Emu* this, int* size )
{
if ( size )
*size = 0;
long gd3_offset = get_le32( header( this )->gd3_offset ) - 0x2C;
if ( gd3_offset < 0 )
return 0;
byte const* gd3 = this->file_begin + header_size + gd3_offset;
long gd3_size = check_gd3_header( gd3, this->file_end - gd3 );
if ( !gd3_size )
return 0;
if ( size )
*size = gd3_size + gd3_header_size;
return gd3;
}
static void get_vgm_length( struct header_t const* h, struct track_info_t* out )
{
long length = get_le32( h->track_duration ) * 10 / 441;
if ( length > 0 )
{
long loop = get_le32( h->loop_duration );
if ( loop > 0 && get_le32( h->loop_offset ) )
{
out->loop_length = loop * 10 / 441;
out->intro_length = length - out->loop_length;
}
else
{
out->length = length; // 1000 / 44100 (VGM files used 44100 as timebase)
out->intro_length = length; // make it clear that track is no longer than length
out->loop_length = 0;
}
}
}
blargg_err_t track_info( struct Vgm_Emu* this, struct track_info_t* out )
{
memset(out, 0, sizeof out);
get_vgm_length( header( this ), out );
int size;
byte const* gd3 = gd3_data( this, &size );
if ( gd3 )
parse_gd3( gd3 + gd3_header_size, gd3 + size, out );
return 0;
}
static blargg_err_t check_vgm_header( struct header_t* h )
{
if ( memcmp( h->tag, "Vgm ", 4 ) )
return gme_wrong_file_type;
return 0;
}
void set_voice( struct Vgm_Emu* this, int i, struct Blip_Buffer* c, struct Blip_Buffer* l, struct Blip_Buffer* r )
{
if ( i < sms_osc_count ) {
int j;
for ( j = sms_osc_count; --j >= 0; )
Sms_apu_set_output( &this->psg, j, c, l, r );
}
}
blargg_err_t setup_fm( struct Vgm_Emu* this );
blargg_err_t Vgm_load_mem( struct Vgm_Emu* this, byte const* new_data, long new_size, bool parse_info )
{
// Unload
this->voice_count = 0;
clear_track_vars( this );
// Clear info
memset( &this->info, 0, sizeof this->info );
assert( offsetof (struct header_t,unused2 [8]) == header_size );
if ( new_size <= header_size )
return gme_wrong_file_type;
// Reset data pointers
this->file_begin = new_data;
this->file_end = new_data + new_size;
struct header_t* h = (struct header_t*) new_data;
RETURN_ERR( check_vgm_header( h ) );
check( get_le32( h.version ) <= 0x150 );
// If this was VGZ file gd3 parse info
if ( parse_info ) {
track_info( this, &this->info );
// If file was trimmed add an
// incomplete token to the game tag
if ( get_le32( h->data_size ) > (unsigned) new_size ) {
*((char *) this->file_end) = cmd_end;
strcat(this->info.game, "(Trimmed VGZ file)" );
}
}
// Get loop
this->loop_begin = this->file_end;
// If file was trimmed don't loop
if ( get_le32( h->loop_offset ) && get_le32( h->data_size ) <= (unsigned) new_size )
this->loop_begin = &new_data [get_le32( h->loop_offset ) + offsetof (struct header_t,loop_offset)];
// PSG rate
this->psg_rate = get_le32( h->psg_rate );
if ( !this->psg_rate )
this->psg_rate = 3579545;
Buffer_clock_rate( &this->stereo_buf, this->psg_rate );
// Disable FM
this->fm_rate = 0;
Ym2612_enable( &this->ym2612, false );
Ym2413_enable( &this->ym2413, false );
Sound_set_tempo( this, 1 );
this->voice_count = sms_osc_count;
RETURN_ERR( setup_fm( this ) );
// do after FM in case output buffer is changed
// setup buffer
this->clock_rate_ = this->psg_rate;
Buffer_clock_rate( &this->buf, this->psg_rate );
// Setup bass
this->buf_changed_count = Buffer_channels_changed_count( &this->buf );
// Post load
Sound_set_tempo( this, this->tempo );
Sound_mute_voices( this, this->mute_mask_ );
return 0;
}
void update_fm_rates( struct Vgm_Emu* this, int* ym2413_rate, int* ym2612_rate );
blargg_err_t init_fm( struct Vgm_Emu* this, double* rate )
{
int ym2612_rate = get_le32( header( this )->ym2612_rate );
int ym2413_rate = get_le32( header( this )->ym2413_rate );
if ( ym2413_rate && get_le32( header( this )->version ) < 0x110 )
update_fm_rates( this, &ym2413_rate, &ym2612_rate );
if ( ym2612_rate )
{
if ( !*rate )
*rate = ym2612_rate / 144.0;
RETURN_ERR( Ym2612_set_rate( &this->ym2612, *rate, ym2612_rate ) );
Ym2612_enable( &this->ym2612, true );
}
else if ( ym2413_rate )
{
if ( !*rate )
*rate = ym2413_rate / 72.0;
int result = Ym2413_set_rate( &this->ym2413, *rate, ym2413_rate );
if ( result == 2 )
return "YM2413 FM sound not supported";
CHECK_ALLOC( !result );
Ym2413_enable( &this->ym2413, true );
}
this->fm_rate = *rate;
return 0;
}
blargg_err_t setup_fm( struct Vgm_Emu* this )
{
double fm_rate = 0.0;
if ( !this->disable_oversampling )
this->fm_rate = this->sample_rate * oversample_factor;
RETURN_ERR( init_fm( this, &fm_rate ) );
if ( uses_fm( this ) )
{
this->voice_count = 8;
RETURN_ERR( Resampler_setup( &this->resampler, fm_rate / this->sample_rate, rolloff, fm_gain * this->gain ) );
RETURN_ERR( Resampler_reset( &this->resampler, Buffer_length( &this->stereo_buf ) * this->sample_rate / 1000 ) );
Sms_apu_volume( &this->psg, 0.195 * fm_gain * this->gain );
}
else
{
Sms_apu_volume( &this->psg, this->gain );
}
return 0;
}
// Emulation
blip_time_t run( struct Vgm_Emu* this, vgm_time_t end_time );
blargg_err_t run_clocks( struct Vgm_Emu* this, blip_time_t* time_io, int msec )
{
*time_io = run( this, msec * this->vgm_rate / 1000 );
Sms_apu_end_frame( &this->psg, *time_io );
return 0;
}
blargg_err_t play_( struct Vgm_Emu* this, long count, sample_t* out )
{
if ( !uses_fm( this ) ) {
long remain = count;
while ( remain )
{
remain -= Buffer_read_samples( &this->buf, &out [count - remain], remain );
if ( remain )
{
if ( this->buf_changed_count != Buffer_channels_changed_count( &this->buf ) )
{
this->buf_changed_count = Buffer_channels_changed_count( &this->buf );
// Remute voices
Sound_mute_voices( this, this->mute_mask_ );
}
int msec = Buffer_length( &this->buf );
blip_time_t clocks_emulated = (blargg_long) msec * this->clock_rate_ / 1000 - 100;
RETURN_ERR( run_clocks( this, &clocks_emulated, msec ) );
assert( clocks_emulated );
Buffer_end_frame( &this->buf, clocks_emulated );
}
}
return 0;
}
Resampler_play( &this->resampler, count, out, &this->stereo_buf );
return 0;
}
// Vgm_Emu_impl
inline int command_len( int command )
{
static byte const lens [0x10] ICONST_ATTR = {
// 0 1 2 3 4 5 6 7 8 9 A B C D E F
1,1,1,2,2,3,1,1,1,1,3,3,4,4,5,5
};
int len = lens [command >> 4];
check( len != 1 );
return len;
}
inline fm_time_t to_fm_time( struct Vgm_Emu* this, vgm_time_t t )
{
return (t * this->fm_time_factor + this->fm_time_offset) >> fm_time_bits;
}
inline blip_time_t to_psg_time( struct Vgm_Emu* this, vgm_time_t t )
{
return (t * this->blip_time_factor) >> blip_time_bits;
}
void write_pcm( struct Vgm_Emu* this, vgm_time_t vgm_time, int amp )
{
if ( this->blip_buf )
{
check( amp >= 0 );
blip_time_t blip_time = to_psg_time( this, vgm_time );
int old = this->dac_amp;
int delta = amp - old;
this->dac_amp = amp;
Blip_set_modified( this->blip_buf );
if ( old >= 0 ) // first write is ignored, to avoid click
Synth_offset_inline( &this->pcm, blip_time, delta, this->blip_buf );
else
this->dac_amp |= this->dac_disabled;
}
}
blip_time_t run( struct Vgm_Emu* this, vgm_time_t end_time )
{
vgm_time_t vgm_time = this->vgm_time;
byte const* pos = this->pos;
if ( pos >= this->file_end )
{
this->emu_track_ended_ = true;
/* if ( pos > data_end )
warning( "Stream lacked end event" ); */
}
while ( vgm_time < end_time && pos < this->file_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 = this->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:
Sms_apu_write_ggstereo( &this->psg, to_psg_time( this, vgm_time ), *pos++ );
break;
case cmd_psg:
Sms_apu_write_data( &this->psg, to_psg_time( this, vgm_time ), *pos++ );
break;
case cmd_delay:
vgm_time += pos [1] * 0x100 + pos [0];
pos += 2;
break;
case cmd_byte_delay:
vgm_time += *pos++;
break;
case cmd_ym2413:
if ( Ym2413_run_until( &this->ym2413, to_fm_time( this, vgm_time ) ) )
Ym2413_write( &this->ym2413, pos [0], pos [1] );
pos += 2;
break;
case cmd_ym2612_port0:
if ( pos [0] == ym2612_dac_port )
{
write_pcm( this, vgm_time, pos [1] );
}
else if ( Ym2612_run_until( &this->ym2612, to_fm_time( this, vgm_time ) ) )
{
if ( pos [0] == 0x2B )
{
this->dac_disabled = (pos [1] >> 7 & 1) - 1;
this->dac_amp |= this->dac_disabled;
}
Ym2612_write0( &this->ym2612, pos [0], pos [1] );
}
pos += 2;
break;
case cmd_ym2612_port1:
if ( Ym2612_run_until( &this->ym2612, to_fm_time( this, vgm_time ) ) )
{
if ( pos [0] == ym2612_dac_pan_port )
{
struct Blip_Buffer* blip_buf = NULL;
switch ( pos [1] >> 6 )
{
case 0: blip_buf = NULL; break;
case 1: blip_buf = &this->stereo_buf.bufs [2]; break;
case 2: blip_buf = &this->stereo_buf.bufs [1]; break;
case 3: blip_buf = &this->stereo_buf.bufs [0]; break;
}
this->blip_buf = blip_buf;
}
Ym2612_write1( &this->ym2612, 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 )
this->pcm_data = pos;
pos += size;
break;
}
case cmd_pcm_seek:
this->pcm_pos = this->pcm_data + pos [3] * 0x1000000 + pos [2] * 0x10000 +
pos [1] * 0x100 + pos [0];
pos += 4;
break;
default: {
int cmd = pos [-1];
switch ( cmd & 0xF0 )
{
case cmd_pcm_delay:
write_pcm( this, vgm_time, *this->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;
/* warning( "Unknown stream event" ); */
}
}
}
}
vgm_time -= end_time;
this->pos = pos;
this->vgm_time = vgm_time;
return to_psg_time( this, end_time );
}
int play_frame( struct Vgm_Emu* this, blip_time_t blip_time, int sample_count, blip_sample_t out [] )
{
// to do: timing is working mostly by luck
int min_pairs = (unsigned) sample_count / 2;
int vgm_time = (min_pairs << fm_time_bits) / this->fm_time_factor - 1;
assert( to_fm_time( this, vgm_time ) <= min_pairs );
int pairs;
while ( (pairs = to_fm_time( this, vgm_time )) < min_pairs )
vgm_time++;
//debug_printf( "pairs: %d, min_pairs: %d\n", pairs, min_pairs );
if ( Ym2612_enabled( &this->ym2612 ) )
{
Ym2612_begin_frame( &this->ym2612, out );
memset( out, 0, pairs * stereo * sizeof *out );
}
else if ( Ym2413_enabled( &this->ym2413 ) )
{
Ym2413_begin_frame( &this->ym2413, out );
}
run( this, vgm_time );
Ym2612_run_until( &this->ym2612, pairs );
Ym2413_run_until( &this->ym2413, pairs );
this->fm_time_offset = (vgm_time * this->fm_time_factor + this->fm_time_offset) - (pairs << fm_time_bits);
Sms_apu_end_frame( &this->psg, blip_time );
return pairs * stereo;
}
// Update pre-1.10 header FM rates by scanning commands
void update_fm_rates( struct Vgm_Emu* this, int* ym2413_rate, int* ym2612_rate )
{
byte const* p = this->file_begin + 0x40;
while ( p < this->file_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 );
}
}
}
// Music Emu
blargg_err_t Vgm_set_sample_rate( struct Vgm_Emu* this, long rate )
{
require( !this->sample_rate ); // sample rate can't be changed once set
RETURN_ERR( Buffer_set_sample_rate( &this->stereo_buf, rate, 1000 / 30 ) );
RETURN_ERR( Buffer_set_sample_rate( &this->buf, rate, 1000 / 20 ) );
// Set bass frequency
Buffer_bass_freq( &this->buf, 80 );
this->sample_rate = rate;
return 0;
}
void Sound_mute_voice( struct Vgm_Emu* this, int index, bool mute )
{
require( (unsigned) index < (unsigned) this->voice_count );
int bit = 1 << index;
int mask = this->mute_mask_ | bit;
if ( !mute )
mask ^= bit;
Sound_mute_voices( this, mask );
}
void Sound_mute_voices( struct Vgm_Emu* this, int mask )
{
require( this->sample_rate ); // sample rate must be set first
this->mute_mask_ = mask;
int i;
for ( i = this->voice_count; i--; )
{
if ( mask & (1 << i) )
{
set_voice( this, i, 0, 0, 0 );
}
else
{
struct channel_t ch = Buffer_channel( &this->buf );
assert( (ch.center && ch.left && ch.right) ||
(!ch.center && !ch.left && !ch.right) ); // all or nothing
set_voice( this, i, ch.center, ch.left, ch.right );
}
}
// TODO: what was this for?
//core.pcm.output( &core.blip_buf );
// TODO: silence PCM if FM isn't used?
if ( uses_fm( this ) )
{
for ( i = sms_osc_count; --i >= 0; )
Sms_apu_set_output( &this->psg, i, ( mask & 0x80 ) ? 0 : &this->stereo_buf.bufs [0], NULL, NULL );
if ( Ym2612_enabled( &this->ym2612 ) )
{
Synth_volume( &this->pcm, (mask & 0x40) ? 0.0 : 0.1115 / 256 * fm_gain * this->gain );
Ym2612_mute_voices( &this->ym2612, mask );
}
if ( Ym2413_enabled( &this->ym2413 ) )
{
int m = mask & 0x3F;
if ( mask & 0x20 )
m |= 0x01E0; // channels 5-8
if ( mask & 0x40 )
m |= 0x3E00;
Ym2413_mute_voices( &this->ym2413, m );
}
}
}
void Sound_set_tempo( struct Vgm_Emu* this, double t )
{
require( this->sample_rate ); // sample rate must be set first
double const min = 0.02;
double const max = 4.00;
if ( t < min ) t = min;
if ( t > max ) t = max;
this->tempo = t;
if ( this->file_begin )
{
this->vgm_rate = (long) (44100 * t + 0.5);
this->blip_time_factor = (int) ((double)
(1 << blip_time_bits) / this->vgm_rate * Blip_clock_rate( &this->stereo_buf.bufs [0] ) + 0.5);
//debug_printf( "blip_time_factor: %ld\n", blip_time_factor );
//debug_printf( "vgm_rate: %ld\n", vgm_rate );
// TODO: remove? calculates vgm_rate more accurately (above differs at most by one Hz only)
//blip_time_factor = (long) floor( double (1L << blip_time_bits) * psg_rate / 44100 / t + 0.5 );
//vgm_rate = (long) floor( double (1L << blip_time_bits) * psg_rate / blip_time_factor + 0.5 );
this->fm_time_factor = 2 + (int) (this->fm_rate * (1 << fm_time_bits) / this->vgm_rate + 0.5);
}
}
void fill_buf( struct Vgm_Emu *this );
blargg_err_t Vgm_start_track( struct Vgm_Emu* this )
{
clear_track_vars( this );
Sms_apu_reset( &this->psg, get_le16( header( this )->noise_feedback ), header( this )->noise_width );
this->blip_buf = &this->stereo_buf.bufs [0];
this->dac_disabled = -1;
this->pos = this->file_begin + header_size;
this->pcm_data = this->pos;
this->pcm_pos = this->pos;
this->dac_amp = -1;
this->vgm_time = 0;
if ( get_le32( header( this )->version ) >= 0x150 )
{
long data_offset = get_le32( header( this )->data_offset );
check( data_offset );
if ( data_offset )
this->pos += data_offset + offsetof (struct header_t,data_offset) - 0x40;
}
if ( uses_fm( this ) )
{
if ( Ym2413_enabled( &this->ym2413 ) )
Ym2413_reset( &this->ym2413 );
if ( Ym2612_enabled( &this->ym2612 ) )
Ym2612_reset( &this->ym2612 );
Buffer_clear( &this->stereo_buf );
Resampler_clear( &this->resampler );
}
this->fm_time_offset = 0;
Buffer_clear( &this->buf );
this->emu_track_ended_ = false;
this->track_ended = false;
if ( !this->ignore_silence )
{
// play until non-silence or end of track
long end;
for ( end = this->max_initial_silence * stereo * this->sample_rate; this->emu_time < end; )
{
fill_buf( this );
if ( this->buf_remain | (int) this->emu_track_ended_ )
break;
}
this->emu_time = this->buf_remain;
this->out_time = 0;
this->silence_time = 0;
this->silence_count = 0;
}
/* return track_ended() ? warning() : 0; */
return 0;
}
// Tell/Seek
blargg_long msec_to_samples( blargg_long msec, long sample_rate )
{
blargg_long sec = msec / 1000;
msec -= sec * 1000;
return (sec * sample_rate + msec * sample_rate / 1000) * stereo;
}
long Track_tell( struct Vgm_Emu* this )
{
blargg_long rate = this->sample_rate * stereo;
blargg_long sec = this->out_time / rate;
return sec * 1000 + (this->out_time - sec * rate) * 1000 / rate;
}
blargg_err_t Track_seek( struct Vgm_Emu* this, long msec )
{
blargg_long time = msec_to_samples( msec, this->sample_rate );
if ( time < this->out_time )
RETURN_ERR( Vgm_start_track( this ) );
return Track_skip( this, time - this->out_time );
}
blargg_err_t skip_( struct Vgm_Emu* this, long count );
blargg_err_t Track_skip( struct Vgm_Emu* this, long count )
{
this->out_time += count;
// remove from silence and buf first
{
long n = min( count, this->silence_count );
this->silence_count -= n;
count -= n;
n = min( count, this->buf_remain );
this->buf_remain -= n;
count -= n;
}
if ( count && !this->emu_track_ended_ )
{
this->emu_time += count;
if ( skip_( this, count ) )
this->emu_track_ended_ = true;
}
if ( !(this->silence_count | this->buf_remain) ) // caught up to emulator, so update track ended
this->track_ended |= this->emu_track_ended_;
return 0;
}
blargg_err_t skip_( struct Vgm_Emu* this, long count )
{
// for long skip, mute sound
const long threshold = 30000;
if ( count > threshold )
{
int saved_mute = this->mute_mask_;
Sound_mute_voices( this, ~0 );
while ( count > threshold / 2 && !this->emu_track_ended_ )
{
RETURN_ERR( play_( this, buf_size, this->buf_ ) );
count -= buf_size;
}
Sound_mute_voices( this, saved_mute );
}
while ( count && !this->emu_track_ended_ )
{
long n = buf_size;
if ( n > count )
n = count;
count -= n;
RETURN_ERR( play_( this, n, this->buf_ ) );
}
return 0;
}
// Fading
void Track_set_fade( struct Vgm_Emu* this, long start_msec, long length_msec )
{
this->fade_step = this->sample_rate * length_msec / (fade_block_size * fade_shift * 1000 / stereo);
this->fade_start = msec_to_samples( start_msec, this->sample_rate );
}
// unit / pow( 2.0, (double) x / step )
static int int_log( blargg_long x, int step, int unit )
{
int shift = x / step;
int fraction = (x - shift * step) * unit / step;
return ((unit - fraction) + (fraction >> 1)) >> shift;
}
void handle_fade( struct Vgm_Emu* this, long out_count, sample_t* out )
{
int i;
for ( i = 0; i < out_count; i += fade_block_size )
{
int const shift = 14;
int const unit = 1 << shift;
int gain = int_log( (this->out_time + i - this->fade_start) / fade_block_size,
this->fade_step, unit );
if ( gain < (unit >> fade_shift) )
this->track_ended = this->emu_track_ended_ = true;
sample_t* io = &out [i];
int count;
for ( count = min( fade_block_size, out_count - i ); count; --count )
{
*io = (sample_t) ((*io * gain) >> shift);
++io;
}
}
}
// Silence detection
void emu_play( struct Vgm_Emu* this, long count, sample_t* out )
{
this->emu_time += count;
if ( !this->emu_track_ended_ ) {
if ( play_( this, count, out ) )
this->emu_track_ended_ = true;
}
else
memset( out, 0, count * sizeof *out );
}
// number of consecutive silent samples at end
static long count_silence( sample_t* begin, long size )
{
sample_t first = *begin;
*begin = silence_threshold; // sentinel
sample_t* p = begin + size;
while ( (unsigned) (*--p + silence_threshold / 2) <= (unsigned) silence_threshold ) { }
*begin = first;
return size - (p - begin);
}
// fill internal buffer and check it for silence
void fill_buf( struct Vgm_Emu* this )
{
assert( !this->buf_remain );
if ( !this->emu_track_ended_ )
{
emu_play( this, buf_size, this->buf_ );
long silence = count_silence( this->buf_, buf_size );
if ( silence < buf_size )
{
this->silence_time = this->emu_time - silence;
this->buf_remain = buf_size;
return;
}
}
this->silence_count += buf_size;
}
blargg_err_t Vgm_play( struct Vgm_Emu* this, long out_count, sample_t* out )
{
if ( this->track_ended )
{
memset( out, 0, out_count * sizeof *out );
}
else
{
require( out_count % stereo == 0 );
assert( this->emu_time >= this->out_time );
// prints nifty graph of how far ahead we are when searching for silence
//debug_printf( "%*s \n", int ((emu_time - out_time) * 7 / sample_rate()), "*" );
long pos = 0;
if ( this->silence_count )
{
// during a run of silence, run emulator at >=2x speed so it gets ahead
long ahead_time = this->silence_lookahead * (this->out_time + out_count - this->silence_time) + this->silence_time;
while ( this->emu_time < ahead_time && !(this->buf_remain | this->emu_track_ended_) )
fill_buf( this );
// fill with silence
pos = min( this->silence_count, out_count );
memset( out, 0, pos * sizeof *out );
this->silence_count -= pos;
if ( this->emu_time - this->silence_time > silence_max * stereo * this->sample_rate )
{
this->track_ended = this->emu_track_ended_ = true;
this->silence_count = 0;
this->buf_remain = 0;
}
}
if ( this->buf_remain )
{
// empty silence buf
long n = min( this->buf_remain, out_count - pos );
memcpy( &out [pos], this->buf_ + (buf_size - this->buf_remain), n * sizeof *out );
this->buf_remain -= n;
pos += n;
}
// generate remaining samples normally
long remain = out_count - pos;
if ( remain )
{
emu_play( this, remain, out + pos );
this->track_ended |= this->emu_track_ended_;
if ( !this->ignore_silence || this->out_time > this->fade_start )
{
// check end for a new run of silence
long silence = count_silence( out + pos, remain );
if ( silence < remain )
this->silence_time = this->emu_time - silence;
if ( this->emu_time - this->silence_time >= buf_size )
fill_buf( this ); // cause silence detection on next play()
}
}
if ( this->out_time > this->fade_start )
handle_fade( this, out_count, out );
}
this->out_time += out_count;
return 0;
}