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/*
* BRLTTY - A background process providing access to the console screen (when in
* text mode) for a blind person using a refreshable braille display.
*
* Copyright (C) 1995-2024 by The BRLTTY Developers.
*
* BRLTTY comes with ABSOLUTELY NO WARRANTY.
*
* This is free software, placed 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. Please see the file LICENSE-LGPL for details.
*
* Web Page: http://brltty.app/
*
* This software is maintained by Dave Mielke <dave@mielke.cc>.
*/
/*
* Miscellaneous FM chip soundcard routines for BRLTTY.
* Implemented by Dave Mielke <dave@mielke.cc>.
* Method gleaned from sccw, a morse code program written
* by Steven J. Merrifield <sjm@ee.latrobe.edu.au> (VK3ESM).
* Must compile with -O2.
* Must link with -lm.
* May compile with -DDEBUG_ADLIB.
*/
#include "prologue.h"
#include "log.h"
#include "async_wait.h"
#include "timing.h"
#include "ports.h"
#include "fm.h"
#include "fm_adlib.h"
const unsigned char AL_channelOffsets[] = {
/* 1 2 3 4 5 6 7 8 9 */
0X00, 0X01, 0X02, 0X08, 0X09, 0X0A, 0X10, 0X11, 0X12
};
const unsigned char AL_channelCount = ARRAY_COUNT(AL_channelOffsets);
static unsigned int portsEnabledCount = 0;
int
fmEnablePorts (int errorLevel) {
if (portsEnabledCount) return 1;
if (enablePorts(errorLevel, ALP_REGISTER, 1)) {
if (enablePorts(errorLevel, ALP_DATA, 1)) {
portsEnabledCount++;
return 1;
}
disablePorts(ALP_REGISTER, 1);
}
return 0;
}
void
fmDisablePorts (void) {
if (!--portsEnabledCount) {
disablePorts(ALP_REGISTER, 1);
disablePorts(ALP_DATA, 1);
}
}
unsigned char
AL_readStatus (void) {
return readPort1(ALP_STATUS);
}
static void
AL_writeDelay (int delay) {
while (delay-- > 0) {
AL_readStatus();
}
}
void
AL_writeRegister (int number, unsigned char data) {
/* logMessage(LOG_DEBUG, "AL_writeRegister: %2.2X=%2.2X", number, data); */
writePort1(ALP_REGISTER, number);
AL_writeDelay(6);
writePort1(ALP_DATA, data);
AL_writeDelay(35);
}
void
fmResetCard (void) {
int number;
for (number=ALR_FIRST; number<=ALR_LAST; ++number) {
AL_writeRegister(number, 0);
}
}
static void
AL_resetTimers (void) {
AL_writeRegister(ALR_TCTL, AL_TCTL_T1MASK|AL_TCTL_T2MASK);
AL_writeRegister(ALR_TCTL, AL_TCTL_RESET);
}
int
fmTestCard (int errorLevel) {
const unsigned char mask = AL_STAT_EXP | AL_STAT_EXP1 | AL_STAT_EXP2;
AL_resetTimers();
if (!(AL_readStatus() & mask)) {
unsigned char status;
AL_writeRegister(ALR_T1DATA, 0xFF);
AL_writeRegister(ALR_TCTL, AL_TCTL_T1START|AL_TCTL_T2MASK);
{
const TimeValue duration = {
.seconds = 0,
.nanoseconds = 80 * NSECS_PER_USEC
};
accurateDelay(&duration);
}
status = AL_readStatus();
AL_resetTimers();
if ((status & mask) == (AL_STAT_EXP | AL_STAT_EXP1)) return 1;
}
logMessage(errorLevel, "FM synthesizer initialization failure");
return 0;
}
static void
AL_evaluatePitch (int pitch, int *exponent, int *mantissa) {
int shift = 21;
while ((*mantissa = (int)((float)pitch * (1 << --shift) / 50000.0)) > 0X3FF);
*exponent = 20 - shift;
}
static void
AL_initiateTone (int channel, int exponent, int mantissa) {
/* logMessage(LOG_DEBUG, "AL_initiateTone: %1.1X[%3.3X]", exponent, mantissa); */
AL_writeRegister(ALR_FREQUENCY_LSB(channel),
(mantissa & 0XFF));
AL_writeRegister(ALR_FREQUENCY_MSB(channel),
(((mantissa >> 8) & 0X3) |
((exponent & 0X7) << AL_OCTAVE_SHIFT) |
AL_FREQ_ON));
}
void
fmStartTone (int channel, int pitch) {
int exponent;
int mantissa;
AL_evaluatePitch(pitch, &exponent, &mantissa);
/* logMessage(LOG_DEBUG, "fmStartTone: %d", pitch); */
AL_initiateTone(channel, exponent, mantissa);
}
void
fmStopTone (int channel) {
AL_writeRegister(ALR_FREQUENCY_MSB(channel), 0);
}
void
fmPlayTone (int channel, unsigned int pitch, unsigned long int duration, unsigned int volume) {
/* Play tone at fundamental frequency. */
AL_writeRegister(ALR_MODULATOR(ALG_EFFECT, channel),
(AL_HARMONIC_1 << AL_HARMONIC_SHIFT));
/* Set the carrier to the fundamental frequency. */
AL_writeRegister(ALR_CARRIER(ALG_EFFECT, channel),
(AL_HARMONIC_1 << AL_HARMONIC_SHIFT));
/* Set the volume (passed in as 0-100) */
AL_writeRegister(ALR_CARRIER(ALG_LEVEL, channel),
((AL_VOLUME_SOFT - ((AL_VOLUME_SOFT * volume) / 100)) << AL_VOLUME_SHIFT));
/* Set fast attack and slow decay. */
AL_writeRegister(ALR_CARRIER(ALG_ATTDEC, channel),
((AL_ATTACK_FAST << AL_ATTACK_SHIFT) |
(AL_DECAY_SLOW << AL_DECAY_SHIFT)));
/* Set soft sustain and fast release. */
AL_writeRegister(ALR_CARRIER(ALG_SUSREL, channel),
((AL_SUSTAIN_SOFT << AL_SUSTAIN_SHIFT) |
(AL_RELEASE_FAST << AL_RELEASE_SHIFT)));
fmStartTone(channel, pitch);
asyncWait(duration);
fmStopTone(channel);
}
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