Listing 4. Stage 2 and 3 in C, integrator.c
#include <stdio.h>
#include <math.h>
#include <sys/time.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <unistd.h>
#define SAMPLE_RATE 44100
#define BLOCKS_PER_SECOND 50
#if defined(LINUX)
#include <sys/soundcard.h>
int SoundFD;
#elif defined(IRIX)
#include <audio.h>
ALconfig Irix_AL_config;
ALport SoundFD;
#elif defined(CYGWIN)
#include <windows.h>
#define NONAMELESSUNION
#define _stdcall STDCALL
typedef HANDLE HTASK;
#include <semaphore.h>
#include <mmsystem.h>
static HWAVEOUT WaveDevice = NULL;
static sem_t WavBufSema;
static void CALLBACK WaveCallBack(HWAVE hWave,
UINT uMsg, DWORD dwInstance,
DWORD dwParam1, DWORD dwParam2) {
if (uMsg == WOM_DONE) {
WAVEHDR * wh = (WAVEHDR *) dwParam1;
HGLOBAL hg;
waveOutUnprepareHeader(WaveDevice, wh,
sizeof(WAVEHDR));
hg = GlobalHandle(wh->lpData);
GlobalUnlock(hg); GlobalFree(hg);
hg = GlobalHandle(hg); GlobalUnlock(hg);
GlobalFree(hg);
sem_post (& WavBufSema);
} }
#endif
int InitSoundSystem(int SampleRate) {
int OK = -1;
#if defined(LINUX)
if ((SoundFD=open("/dev/dsp", O_WRONLY)) >=0) {
int OSS_format = AFMT_S16_LE;
int OSS_speed = SampleRate;
ioctl(SoundFD, SNDCTL_DSP_RESET, 0);
if ((ioctl(SoundFD, SNDCTL_DSP_SETFMT,
&OSS_format) != -1) &&
(OSS_format == AFMT_S16_LE) &&
(ioctl(SoundFD, SNDCTL_DSP_SPEED,
&OSS_speed ) != -1) &&
(OSS_speed == SampleRate)) {
OK = SoundFD;
} }
#elif defined(IRIX)
long PV [10] = {
AL_LEFT_SPEAKER_GAIN, 10,
AL_RIGHT_SPEAKER_GAIN, 10,
AL_OUTPUT_RATE,
};
PV [5] = AL_RATE_44100;
if ((ALsetparams(AL_DEFAULT_DEVICE,PV,6)==0) &&
((Irix_AL_config = ALnewconfig()) != NULL)){
ALsetchannels (Irix_AL_config, AL_STEREO);
ALsetqueuesize (Irix_AL_config, SAMPLE_RATE);
ALsetwidth (Irix_AL_config, AL_SAMPLE_16);
if (((SoundFD=ALopenport("Speaker","w",
Irix_AL_config)) != NULL)) OK = 0;
}
#elif defined(CYGWIN)
WaveDevice = NULL;
sem_init (& WavBufSema, 0, BLOCKS_PER_SECOND);
if (waveOutGetNumDevs() > 0) {
WAVEFORMATEX outFormatex;
outFormatex.wFormatTag = WAVE_FORMAT_PCM;
outFormatex.wBitsPerSample = 16;
outFormatex.nChannels = 1;
outFormatex.nSamplesPerSec = SAMPLE_RATE;
outFormatex.nBlockAlign = sizeof(short int);
outFormatex.nAvgBytesPerSec =
outFormatex.nSamplesPerSec * sizeof(short int);
if (waveOutOpen(&WaveDevice, WAVE_MAPPER,
&outFormatex, (DWORD) WaveCallBack, 0,
CALLBACK_FUNCTION) == MMSYSERR_NOERROR)
OK = 0;
}
#endif
return OK;
}
void SoundOutAndWait(short int * Sample,
int HowMany) {
int HowManyBytes = HowMany * sizeof(short int);
#if defined(LINUX)
write(SoundFD, Sample, HowManyBytes);
#elif defined(IRIX)
ALwritesamps (SoundFD, Sample, HowMany);
#elif defined(CYGWIN)
HGLOBAL HGheader = GlobalAlloc (GMEM_MOVEABLE |
GMEM_ZEROINIT, sizeof(WAVEHDR));
HGLOBAL HGdata = GlobalAlloc (GMEM_MOVEABLE,
HowManyBytes);
LPWAVEHDR WaveHeaderPtr = GlobalLock(HGheader);
WaveHeaderPtr->dwBufferLength = HowManyBytes;
WaveHeaderPtr->lpData = GlobalLock(HGdata);
CopyMemory(WaveHeaderPtr->lpData, Sample,
HowManyBytes);
waveOutPrepareHeader(WaveDevice, WaveHeaderPtr,
sizeof(WAVEHDR));
waveOutWrite (WaveDevice, WaveHeaderPtr,
sizeof(WAVEHDR));
sem_wait (& WavBufSema);
#endif
}
int main (int argc, char *argv[]) {
double k=0.05, B=7.5, x1=3.0, dx=4.0,
dt=M_PI/100.0, ddt, x0, x2;
int i, j = 0;
if (InitSoundSystem(SAMPLE_RATE) < 0) exit(0);
ddt = dt * dt; x0 = x1 - dx*dt;
while (1) {
short int SampleBuffer[SAMPLE_RATE /
BLOCKS_PER_SECOND];
fd_set stdin_set;
struct timeval timeout = { 0, 0 };
FD_ZERO(& stdin_set); /* non-blocking read */
FD_SET(fileno(stdin), & stdin_set);
if (select(fileno(stdin)+1, & stdin_set,
NULL, NULL, & timeout) > 0) {
char line[128], Name[128];
float Value;
fgets(line, sizeof(line), stdin);
sscanf (line, "%s %f", Name, &Value);
if (strcmp(Name,"k")==0) k=(double) Value;
if (strcmp(Name,"B")==0) B=(double) Value;
}
for (i=0; i<(SAMPLE_RATE/BLOCKS_PER_SECOND);
i++, j++) {
SampleBuffer[i] = 4096 * x1;
x2 = (ddt*B * cos(j*dt) + (2+dt*k)*x1 -
x0 - ddt*x1*x1*x1) / (1 + dt * k);
if ((j%1000) == 0) /* Poincare section */
printf("%f %f\n", x2, (x2-x1)/dt);
x0=x1; x1=x2;
}
SoundOutAndWait(SampleBuffer,
SAMPLE_RATE / BLOCKS_PER_SECOND);
}
return 0;
}
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