From f40bfc9267b13b54e6379dfe7539447662879d24 Mon Sep 17 00:00:00 2001 From: Sean Bartell Date: Sat, 25 Jun 2011 21:32:25 -0400 Subject: Add codecs to librbcodec. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change-Id: Id7f4717d51ed02d67cb9f9cb3c0ada4a81843f97 Reviewed-on: http://gerrit.rockbox.org/137 Reviewed-by: Nils Wallménius Tested-by: Nils Wallménius --- lib/rbcodec/codecs/libgme/sms_apu.c | 306 ++++++++++++++++++++++++++++++++++++ 1 file changed, 306 insertions(+) create mode 100644 lib/rbcodec/codecs/libgme/sms_apu.c (limited to 'lib/rbcodec/codecs/libgme/sms_apu.c') diff --git a/lib/rbcodec/codecs/libgme/sms_apu.c b/lib/rbcodec/codecs/libgme/sms_apu.c new file mode 100644 index 0000000000..379fcf1cbf --- /dev/null +++ b/lib/rbcodec/codecs/libgme/sms_apu.c @@ -0,0 +1,306 @@ +// Sms_Snd_Emu 0.1.1. http://www.slack.net/~ant/ + +#include "sms_apu.h" + +/* Copyright (C) 2003-2008 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" + +int const noise_osc = 3; + +void Sms_apu_volume( struct Sms_Apu* this, int vol ) +{ + vol = (vol - (vol*3)/20) / sms_osc_count / 64; + Synth_volume( &this->synth, vol ); +} + +static inline int calc_output( struct Sms_Apu* this, int i ) +{ + int flags = this->ggstereo >> i; + return (flags >> 3 & 2) | (flags & 1); +} + +void Sms_apu_set_output( struct Sms_Apu* this, int i, struct Blip_Buffer* center, struct Blip_Buffer* left, struct Blip_Buffer* right ) +{ +#if defined(ROCKBOX) + (void) left; + (void) right; +#endif + + // Must be silent (all NULL), mono (left and right NULL), or stereo (none NULL) + require( !center || (center && !left && !right) || (center && left && right) ); + require( (unsigned) i < sms_osc_count ); // fails if you pass invalid osc index + + if ( center ) + { + unsigned const divisor = 16384 * 16 * 2; + this->min_tone_period = ((unsigned) Blip_clock_rate( center ) + divisor/2) / divisor; + } + + if ( !center || !left || !right ) + { + left = center; + right = center; + } + + struct Osc* o = &this->oscs [i]; + o->outputs [0] = NULL; + o->outputs [1] = right; + o->outputs [2] = left; + o->outputs [3] = center; + o->output = o->outputs [calc_output( this, i )]; +} + +static inline unsigned fibonacci_to_galois_lfsr( unsigned fibonacci, int width ) +{ + unsigned galois = 0; + while ( --width >= 0 ) + { + galois = (galois << 1) | (fibonacci & 1); + fibonacci >>= 1; + } + return galois; +} + +void Sms_apu_reset( struct Sms_Apu* this, unsigned feedback, int noise_width ) +{ + this->last_time = 0; + this->latch = 0; + this->ggstereo = 0; + + // Calculate noise feedback values + if ( !feedback || !noise_width ) + { + feedback = 0x0009; + noise_width = 16; + } + this->looped_feedback = 1 << (noise_width - 1); + this->noise_feedback = fibonacci_to_galois_lfsr( feedback, noise_width ); + + // Reset oscs + int i; + for ( i = sms_osc_count; --i >= 0; ) + { + struct Osc* o = &this->oscs [i]; + o->output = NULL; + o->last_amp = 0; + o->delay = 0; + o->phase = 0; + o->period = 0; + o->volume = 15; // silent + } + + this->oscs [noise_osc].phase = 0x8000; + Sms_apu_write_ggstereo( this, 0, 0xFF ); +} + +void Sms_apu_init( struct Sms_Apu* this ) +{ + this->min_tone_period = 7; + + Synth_init( &this->synth ); + + // Clear outputs to NULL FIRST + this->ggstereo = 0; + + int i; + for ( i = sms_osc_count; --i >= 0; ) + Sms_apu_set_output( this, i, NULL, NULL, NULL ); + + Sms_apu_volume( this, (int)FP_ONE_VOLUME ); + Sms_apu_reset( this, 0, 0 ); +} + +static void run_until( struct Sms_Apu* this, blip_time_t end_time ) +{ + require( end_time >= this->last_time ); + if ( end_time <= this->last_time ) + return; + + // Synthesize each oscillator + int idx; + for ( idx = sms_osc_count; --idx >= 0; ) + { + struct Osc* osc = &this->oscs [idx]; + int vol = 0; + int amp = 0; + + // Determine what will be generated + struct Blip_Buffer* const out = osc->output; + if ( out ) + { + // volumes [i] ~= 64 * pow( 1.26, 15 - i ) / pow( 1.26, 15 ) + static unsigned char const volumes [16] = { + 64, 50, 40, 32, 25, 20, 16, 13, 10, 8, 6, 5, 4, 3, 2, 0 + }; + + vol = volumes [osc->volume]; + amp = (osc->phase & 1) * vol; + + // Square freq above 16 kHz yields constant amplitude at half volume + if ( idx != noise_osc && osc->period < this->min_tone_period ) + { + amp = vol >> 1; + vol = 0; + } + + // Update amplitude + int delta = amp - osc->last_amp; + if ( delta ) + { + osc->last_amp = amp; + Synth_offset( &this->synth, this->last_time, delta, out ); + Blip_set_modified( out ); + } + } + + // Generate wave + blip_time_t time = this->last_time + osc->delay; + if ( time < end_time ) + { + // Calculate actual period + int period = osc->period; + if ( idx == noise_osc ) + { + period = 0x20 << (period & 3); + if ( period == 0x100 ) + period = this->oscs [2].period * 2; + } + period *= 0x10; + if ( !period ) + period = 0x10; + + // Maintain phase when silent + int phase = osc->phase; + if ( !vol ) + { + int count = (end_time - time + period - 1) / period; + time += count * period; + if ( idx != noise_osc ) // TODO: maintain noise LFSR phase? + phase ^= count & 1; + } + else + { + int delta = amp * 2 - vol; + + if ( idx != noise_osc ) + { + // Square + do + { + delta = -delta; + Synth_offset( &this->synth, time, delta, out ); + time += period; + } + while ( time < end_time ); + phase = (delta >= 0); + } + else + { + // Noise + unsigned const feedback = (osc->period & 4 ? this->noise_feedback : this->looped_feedback); + do + { + unsigned changed = phase + 1; + phase = ((phase & 1) * feedback) ^ (phase >> 1); + if ( changed & 2 ) // true if bits 0 and 1 differ + { + delta = -delta; + Synth_offset_inline( &this->synth, time, delta, out ); + } + time += period; + } + while ( time < end_time ); + check( phase ); + } + osc->last_amp = (phase & 1) * vol; + Blip_set_modified( out ); + } + osc->phase = phase; + } + osc->delay = time - end_time; + } + this->last_time = end_time; +} + +void Sms_apu_write_ggstereo( struct Sms_Apu* this, blip_time_t time, int data ) +{ + require( (unsigned) data <= 0xFF ); + + run_until( this, time ); + this->ggstereo = data; + + int i; + for ( i = sms_osc_count; --i >= 0; ) + { + struct Osc* osc = &this->oscs [i]; + + struct Blip_Buffer* old = osc->output; + osc->output = osc->outputs [calc_output( this, i )]; + if ( osc->output != old ) + { + int delta = -osc->last_amp; + if ( delta ) + { + osc->last_amp = 0; + if ( old ) + { + Blip_set_modified( old ); + Synth_offset( &this->synth, this->last_time, delta, old ); + } + } + } + } +} + +void Sms_apu_write_data( struct Sms_Apu* this, blip_time_t time, int data ) +{ + require( (unsigned) data <= 0xFF ); + + run_until( this, time ); + + if ( data & 0x80 ) + this->latch = data; + + // We want the raw values written so our save state format can be + // as close to hardware as possible and unspecific to any emulator. + int idx = this->latch >> 5 & 3; + struct Osc* osc = &this->oscs [idx]; + if ( this->latch & 0x10 ) + { + osc->volume = data & 0x0F; + } + else + { + if ( idx == noise_osc ) + osc->phase = 0x8000; // reset noise LFSR + + // Replace high 6 bits/low 4 bits of register with data + int lo = osc->period; + int hi = data << 4; + if ( idx == noise_osc || (data & 0x80) ) + { + hi = lo; + lo = data; + } + osc->period = (hi & 0x3F0) | (lo & 0x00F); + } +} + +void Sms_apu_end_frame( struct Sms_Apu* this, blip_time_t end_time ) +{ + if ( end_time > this->last_time ) + run_until( this, end_time ); + + this->last_time -= end_time; + assert( this->last_time >= 0 ); +} -- cgit v1.2.3