85 lines
2.5 KiB
C++
85 lines
2.5 KiB
C++
/*
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AppleWin : An Apple //e emulator for Windows
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Copyright (C) 1994-1996, Michael O'Brien
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Copyright (C) 1999-2001, Oliver Schmidt
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Copyright (C) 2002-2005, Tom Charlesworth
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Copyright (C) 2006-2007, Tom Charlesworth, Michael Pohoreski
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AppleWin 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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AppleWin 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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You should have received a copy of the GNU General Public License
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along with AppleWin; 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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/*
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SAM.CPP
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Emulate an 8 bit DAC (eg: SAM card) which writes unsigned byte
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data written to its IO area to the audio buffer (as used by the speaker).
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This merges the data with the speaker stream, reducing the volume
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of the Apple speaker when active.
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Riccardo Macri Mar 2015
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*/
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#include "StdAfx.h"
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#include "AppleWin.h"
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#include "Memory.h"
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#include "SAM.h"
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#include "Speaker.h"
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//
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// Write 8 bit data to speaker. Emulates a "SAM" speech card DAC
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//
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static BYTE __stdcall IOWrite_DAC(WORD pc, WORD addr, BYTE bWrite, BYTE d, ULONG nCyclesLeft)
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{
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// Emulate audio from an 8 bit DAC
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// only if using wave data
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// uses the existing speaker for the timing but then
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// substitutes the analog data which gets subsequently
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// sent to audio out
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byte mb_res;
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if (soundtype == SOUND_WAVE)
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{
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// use existing speaker code to bring timing up to date
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mb_res = SpkrToggle(pc, addr, bWrite, d, nCyclesLeft);
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// 8 bit card WAV driver (scaled by 256)
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// 0xFF 255 0x7f 127
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// 0x80 128 0x00 0
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// 0x7f 127 0xFF -1
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// 0x00 0 0x80 -128
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// replace regular speaker output with 8 bit DAC value
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// regular speaker data still audible but quieter until speaker
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// goes idle (so both work simultaneously)
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g_nSpeakerData = (d ^ 0x80) << 8;
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// make speaker quieter so eg: a metronome click through the
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// Apple speaker is softer vs. the analogue SAM output
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g_quieterSpeaker = 1;
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}
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else
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mb_res = MemReadFloatingBus(nCyclesLeft);
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return mb_res;
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}
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void ConfigureDAC(LPBYTE pCxRomPeripheral, UINT uSlot)
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{
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RegisterIoHandler(uSlot,IO_Null,IOWrite_DAC,IO_Null,IO_Null, NULL, NULL);
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}
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