mirror of https://github.com/stella-emu/stella.git
Improved TIA sound emulation library which includes support for mono and
stereo output. git-svn-id: svn://svn.code.sf.net/p/stella/code/trunk@764 8b62c5a3-ac7e-4cc8-8f21-d9a121418aba
This commit is contained in:
bwmott
parent
88464f6935
commit
28946ba589
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//============================================================================
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//
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// SSSS tt lll lll
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// SS SS tt ll ll
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// SS tttttt eeee ll ll aaaa
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// SSSS tt ee ee ll ll aa
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// SS tt eeeeee ll ll aaaaa -- "An Atari 2600 VCS Emulator"
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// SS SS tt ee ll ll aa aa
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// SSSS ttt eeeee llll llll aaaaa
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//
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// Copyright (c) 1995-2005 by Bradford W. Mott
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//
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: TIASnd.cxx,v 1.1 2005-09-04 23:48:33 bwmott Exp $
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//============================================================================
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#include "System.hxx"
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#include "TIASnd.hxx"
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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TIASound::TIASound(Int32 outputFrequency, uInt32 channels)
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: myOutputFrequency(outputFrequency),
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myChannels(channels),
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myOutputCounter(0),
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myVolumePercentage(100)
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{
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reset();
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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TIASound::~TIASound()
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{
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::reset()
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{
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myAUDC[0] = myAUDC[1] = myAUDF[0] = myAUDF[1] = myAUDV[0] = myAUDV[1] = 0;
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myP4[0] = myP5[0] = myP4[1] = myP5[1] = 1;
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myFreqDiv[0].set(0);
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myFreqDiv[1].set(0);
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myOutputCounter = 0;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::outputFrequency(uInt32 freq)
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{
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myOutputFrequency = freq;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::channels(uInt32 number)
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{
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if(number == 2)
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myChannels = 2;
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else
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myChannels = 1;
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::set(uInt16 address, uInt8 value)
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{
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switch(address)
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{
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case 0x15: // AUDC0
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myAUDC[0] = value & 0x0f;
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break;
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case 0x16: // AUDC1
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myAUDC[1] = value & 0x0f;
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break;
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case 0x17: // AUDF0
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myAUDF[0] = value & 0x1f;
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myFreqDiv[0].set(myAUDF[0]);
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break;
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case 0x18: // AUDF1
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myAUDF[1] = value & 0x1f;
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myFreqDiv[1].set(myAUDF[1]);
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break;
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case 0x19: // AUDV0
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myAUDV[0] = value & 0x0f;
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break;
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case 0x1a: // AUDV1
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myAUDV[1] = value & 0x0f;
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break;
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default:
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break;
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}
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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uInt8 TIASound::get(uInt16 address)
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{
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switch(address)
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{
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case 0x15: // AUDC0
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return myAUDC[0];
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case 0x16: // AUDC1
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return myAUDC[1];
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case 0x17: // AUDF0
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return myAUDF[0];
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case 0x18: // AUDF1
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return myAUDF[1];
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case 0x19: // AUDV0
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return myAUDV[0];
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case 0x1a: // AUDV1
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return myAUDV[1];
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default:
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return 0;
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}
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::volume(uInt32 percent)
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{
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if((percent >= 0) && (percent <= 100))
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{
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myVolumePercentage = percent;
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}
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}
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// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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void TIASound::process(uInt8* buffer, uInt32 samples)
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{
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Int32 v0 = ((myAUDV[0] << 2) * myVolumePercentage) / 100;
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Int32 v1 = ((myAUDV[1] << 2) * myVolumePercentage) / 100;
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// Loop until the sample buffer is full
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while(samples > 0)
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{
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// Process both sound channels
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for(uInt32 c = 0; c < 2; ++c)
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{
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// Update P4 & P5 registers for channel if freq divider outputs a pulse
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if((myFreqDiv[c].clock()))
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{
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switch(myAUDC[c])
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{
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case 0x00: // Set to 1
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{
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// Shift a 1 into the 4-bit register each clock
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myP4[c] = (myP4[c] << 1) | 0x01;
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break;
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}
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case 0x01: // 4 bit poly
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{
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// Clock P4 as a standard 4-bit LSFR taps at bits 3 & 2
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myP4[c] = (myP4[c] & 0x0f) ?
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((myP4[c] << 1) | (((myP4[c] & 0x08) ? 1 : 0) ^
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((myP4[c] & 0x04) ? 1 : 0))) : 1;
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break;
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}
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case 0x02: // div 31 -> 4 bit poly
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// This does the divide-by 31 with length 13:18
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if((myP5[c] & 0x0f) == 0x08)
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{
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// Clock P4 as a standard 4-bit LSFR taps at bits 3 & 2
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myP4[c] = (myP4[c] & 0x0f) ?
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((myP4[c] << 1) | (((myP4[c] & 0x08) ? 1 : 0) ^
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((myP4[c] & 0x04) ? 1 : 0))) : 1;
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}
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break;
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}
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case 0x03: // 5 bit poly -> 4 bit poly
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// P5 clocks the 4 bit poly
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if(myP5[c] & 0x10)
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{
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// Clock P4 as a standard 4-bit LSFR taps at bits 3 & 2
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myP4[c] = (myP4[c] & 0x0f) ?
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((myP4[c] << 1) | (((myP4[c] & 0x08) ? 1 : 0) ^
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((myP4[c] & 0x04) ? 1 : 0))) : 1;
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}
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break;
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}
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case 0x04: // div 2
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{
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// Clock P4 toggling the lower bit (divide by 2)
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myP4[c] = (myP4[c] << 1) | ((myP4[c] & 0x01) ? 0 : 1);
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break;
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}
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case 0x05: // div 2
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{
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// Clock P4 toggling the lower bit (divide by 2)
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myP4[c] = (myP4[c] << 1) | ((myP4[c] & 0x01) ? 0 : 1);
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break;
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}
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case 0x06: // div 31 -> div 2
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// This does the divide-by 31 with length 13:18
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if((myP5[c] & 0x0f) == 0x08)
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{
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// Clock P4 toggling the lower bit (divide by 2)
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myP4[c] = (myP4[c] << 1) | ((myP4[c] & 0x01) ? 0 : 1);
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}
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break;
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}
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case 0x07: // 5 bit poly -> div 2
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// P5 clocks the 4 bit register
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if(myP5[c] & 0x10)
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{
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// Clock P4 toggling the lower bit (divide by 2)
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myP4[c] = (myP4[c] << 1) | ((myP4[c] & 0x01) ? 0 : 1);
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}
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break;
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}
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case 0x08: // 9 bit poly
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{
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// Clock P5 & P4 as a standard 9-bit LSFR taps at 8 & 4
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myP5[c] = ((myP5[c] & 0x1f) || (myP4[c] & 0x0f)) ?
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((myP5[c] << 1) | (((myP4[c] & 0x08) ? 1 : 0) ^
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((myP5[c] & 0x10) ? 1 : 0))) : 1;
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myP4[c] = (myP4[c] << 1) | ((myP5[c] & 0x20) ? 1 : 0);
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break;
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}
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case 0x09: // 5 bit poly
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// Clock value out of P5 into P4 with no modification
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myP4[c] = (myP4[c] << 1) | ((myP5[c] & 0x20) ? 1 : 0);
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break;
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}
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case 0x0a: // div 31
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// This does the divide-by 31 with length 13:18
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if((myP5[c] & 0x0f) == 0x08)
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{
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// Feed bit 4 of P5 into P4 (this will toggle back and forth)
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myP4[c] = (myP4[c] << 1) | ((myP5[c] & 0x10) ? 1 : 0);
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}
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break;
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}
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case 0x0b: // Set last 4 bits to 1
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{
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// A 1 is shifted into the 4-bit register each clock
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myP4[c] = (myP4[c] << 1) | 0x01;
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break;
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}
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case 0x0c: // div 6
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{
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// Use 4-bit register to generate sequence 000111000111
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myP4[c] = (~myP4[c] << 1) |
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((!(!(myP4[c] & 4) && ((myP4[c] & 7)))) ? 0 : 1);
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break;
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}
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case 0x0d: // div 6
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{
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// Use 4-bit register to generate sequence 000111000111
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myP4[c] = (~myP4[c] << 1) |
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((!(!(myP4[c] & 4) && ((myP4[c] & 7)))) ? 0 : 1);
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break;
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}
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case 0x0e: // div 31 -> div 6
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// This does the divide-by 31 with length 13:18
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if((myP5[c] & 0x0f) == 0x08)
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{
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// Use 4-bit register to generate sequence 000111000111
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myP4[c] = (~myP4[c] << 1) |
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((!(!(myP4[c] & 4) && ((myP4[c] & 7)))) ? 0 : 1);
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}
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break;
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}
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case 0x0f: // poly 5 -> div 6
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{
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// Clock P5 as a standard 5-bit LSFR taps at bits 4 & 2
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myP5[c] = (myP5[c] & 0x1f) ?
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((myP5[c] << 1) | (((myP5[c] & 0x10) ? 1 : 0) ^
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((myP5[c] & 0x04) ? 1 : 0))) : 1;
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// Use poly 5 to clock 4-bit div register
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if(myP5[c] & 0x10)
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{
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// Use 4-bit register to generate sequence 000111000111
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myP4[c] = (~myP4[c] << 1) |
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((!(!(myP4[c] & 4) && ((myP4[c] & 7)))) ? 0 : 1);
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}
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break;
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}
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}
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}
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}
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myOutputCounter += myOutputFrequency;
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if(myChannels == 1)
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{
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// Handle mono sample generation
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while((samples > 0) && (myOutputCounter >= TIASoundFrequency))
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{
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*(buffer++) = (((myP4[0] & 8) ? v0 : 0) +
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((myP4[1] & 8) ? v1 : 0)) + 128;
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myOutputCounter -= TIASoundFrequency;
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samples--;
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}
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}
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else
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{
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// Handle stereo sample generation
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while((samples > 0) && (myOutputCounter >= TIASoundFrequency))
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{
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*(buffer++) = ((myP4[0] & 8) ? v0 : 0) + 128;
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*(buffer++) = ((myP4[1] & 8) ? v1 : 0) + 128;
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myOutputCounter -= TIASoundFrequency;
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samples--;
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}
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}
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}
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}
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@ -0,0 +1,141 @@
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//============================================================================
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//
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// SSSS tt lll lll
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// SS SS tt ll ll
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// SS tttttt eeee ll ll aaaa
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// SSSS tt ee ee ll ll aa
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// SS tt eeeeee ll ll aaaaa -- "An Atari 2600 VCS Emulator"
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// SS SS tt ee ll ll aa aa
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// SSSS ttt eeeee llll llll aaaaa
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//
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// Copyright (c) 1995-2005 by Bradford W. Mott
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//
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// See the file "license" for information on usage and redistribution of
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// this file, and for a DISCLAIMER OF ALL WARRANTIES.
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//
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// $Id: TIASnd.hxx,v 1.1 2005-09-04 23:48:33 bwmott Exp $
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//============================================================================
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#ifndef TIASOUND_HXX
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#define TIASOUND_HXX
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#include "bspf.hxx"
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/**
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This class implements a fairly accurate emulation of the TIA sound
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hardware.
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@author Bradford W. Mott
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@version $Id: TIASnd.hxx,v 1.1 2005-09-04 23:48:33 bwmott Exp $
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*/
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class TIASound
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{
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public:
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static const int TIASoundFrequency = 31400;
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public:
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/**
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Create a new TIA Sound object using the specified output frequency
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*/
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TIASound(Int32 outputFrequency = TIASoundFrequency, uInt32 channels = 1);
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/**
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Destructor
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*/
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virtual ~TIASound();
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public:
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/**
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Reset the sound emulation to its power-on state
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*/
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void reset();
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/**
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Set the frequency output samples should be generated at
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*/
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void outputFrequency(uInt32 freq);
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/**
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Selects the number of audio channels per sample (1 = mono, 2 = stereo)
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*/
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void channels(uInt32 number);
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public:
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/**
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Sets the specified sound register to the given value
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@param address Register address
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@param value Value to store in the register
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*/
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void set(uInt16 address, uInt8 value);
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/**
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Gets the specified sound register's value
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@param address Register address
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*/
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||||
uInt8 get(uInt16 address);
|
||||
|
||||
/**
|
||||
Create sound samples based on the current sound register settings
|
||||
in the specified buffer. NOTE: If channels is set to stereo then
|
||||
the buffer will need to be twice as long as the number of samples.
|
||||
|
||||
@param buffer The location to store generated samples
|
||||
@param samples The number of samples to generate
|
||||
*/
|
||||
void process(uInt8* buffer, uInt32 samples);
|
||||
|
||||
/**
|
||||
Set the volume of the samples created (0-100)
|
||||
*/
|
||||
void volume(uInt32 percent);
|
||||
|
||||
private:
|
||||
/**
|
||||
Frequency divider class which outputs 1 after "divide-by" clocks. This
|
||||
is used to divide the main frequency by the values 1 to 32.
|
||||
*/
|
||||
class FreqDiv
|
||||
{
|
||||
public:
|
||||
FreqDiv()
|
||||
{
|
||||
myDivideByValue = myCounter = 0;
|
||||
}
|
||||
|
||||
void set(uInt32 divideBy)
|
||||
{
|
||||
myDivideByValue = divideBy;
|
||||
}
|
||||
|
||||
bool clock()
|
||||
{
|
||||
if(++myCounter > myDivideByValue)
|
||||
{
|
||||
myCounter = 0;
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
private:
|
||||
uInt32 myDivideByValue;
|
||||
uInt32 myCounter;
|
||||
};
|
||||
|
||||
private:
|
||||
uInt8 myAUDC[2];
|
||||
uInt8 myAUDF[2];
|
||||
uInt8 myAUDV[2];
|
||||
|
||||
FreqDiv myFreqDiv[2]; // Frequency dividers
|
||||
uInt8 myP4[2]; // 4-bit register LFSR (lower 4 bits used)
|
||||
uInt8 myP5[2]; // 5-bit register LFSR (lower 5 bits used)
|
||||
|
||||
Int32 myOutputFrequency;
|
||||
Int32 myOutputCounter;
|
||||
uInt32 myChannels;
|
||||
uInt32 myVolumePercentage;
|
||||
};
|
||||
#endif
|
||||
Loading…
Reference in New Issue