// --------------------------------------------------------------------------- // This file is part of reSID, a MOS6581 SID emulator engine. // Copyright (C) 2004 Dag Lem // // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 2 of the License, or // (at your option) any later version. // // This program 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 General Public License for more details. // // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA // --------------------------------------------------------------------------- #define __VOICE_CC__ #include "voice.h" RESID_NAMESPACE_START // ---------------------------------------------------------------------------- // Constructor. // ---------------------------------------------------------------------------- Voice::Voice() : muted(false) { //set_chip_model(MOS6581); {//instead: wave_zero = 0x380; voice_DC = 0x800*0xff; } } // ---------------------------------------------------------------------------- // Set chip model. // ---------------------------------------------------------------------------- /* void Voice::set_chip_model(chip_model model) { wave.set_chip_model(model); if (model == MOS6581) { // The waveform D/A converter introduces a DC offset in the signal // to the envelope multiplying D/A converter. The "zero" level of // the waveform D/A converter can be found as follows: // // Measure the "zero" voltage of voice 3 on the SID audio output // pin, routing only voice 3 to the mixer ($d417 = $0b, $d418 = // $0f, all other registers zeroed). // // Then set the sustain level for voice 3 to maximum and search for // the waveform output value yielding the same voltage as found // above. This is done by trying out different waveform output // values until the correct value is found, e.g. with the following // program: // // lda #$08 // sta $d412 // lda #$0b // sta $d417 // lda #$0f // sta $d418 // lda #$f0 // sta $d414 // lda #$21 // sta $d412 // lda #$01 // sta $d40e // // ldx #$00 // lda #$38 ; Tweak this to find the "zero" level //l cmp $d41b // bne l // stx $d40e ; Stop frequency counter - freeze waveform output // brk // // The waveform output range is 0x000 to 0xfff, so the "zero" // level should ideally have been 0x800. In the measured chip, the // waveform output "zero" level was found to be 0x380 (i.e. $d41b // = 0x38) at 5.94V. wave_zero = 0x380; // The envelope multiplying D/A converter introduces another DC // offset. This is isolated by the following measurements: // // * The "zero" output level of the mixer at full volume is 5.44V. // * Routing one voice to the mixer at full volume yields // 6.75V at maximum voice output (wave = 0xfff, sustain = 0xf) // 5.94V at "zero" voice output (wave = any, sustain = 0x0) // 5.70V at minimum voice output (wave = 0x000, sustain = 0xf) // * The DC offset of one voice is (5.94V - 5.44V) = 0.50V // * The dynamic range of one voice is |6.75V - 5.70V| = 1.05V // * The DC offset is thus 0.50V/1.05V ~ 1/2 of the dynamic range. // // Note that by removing the DC offset, we get the following ranges for // one voice: // y > 0: (6.75V - 5.44V) - 0.50V = 0.81V // y < 0: (5.70V - 5.44V) - 0.50V = -0.24V // The scaling of the voice amplitude is not symmetric about y = 0; // this follows from the DC level in the waveform output. voice_DC = 0x800*0xff; } else { // No DC offsets in the MOS8580. wave_zero = 0x800; voice_DC = 0; } } */ // ---------------------------------------------------------------------------- // Set sync source. // ---------------------------------------------------------------------------- void Voice::set_sync_source(Voice* source) { wave.set_sync_source(&source->wave); } // ---------------------------------------------------------------------------- // Register functions. // ---------------------------------------------------------------------------- void Voice::writeCONTROL_REG(reg8 control) { wave.writeCONTROL_REG(control); envelope.writeCONTROL_REG(control); } // ---------------------------------------------------------------------------- // SID reset. // ---------------------------------------------------------------------------- void Voice::reset() { wave.reset(); envelope.reset(); } // ---------------------------------------------------------------------------- // Voice mute. // ---------------------------------------------------------------------------- void Voice::mute(bool enable) { // enable = true (means voice is muted) muted = enable; } RESID_NAMESPACE_STOP