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