Square wave runs fine in terminal but not in Qt Creator[SOLVED]

ogopa

Hi guys.
I have a program that generates a sine wave and a square wave using user inputs of frequency and amplitude. When I run the program in terminal in linux with a g++ compiler, it runs perfectly.
But when I run it in Qt Creator, the sine wave runs perfectly, but the square wave doesn't, it has gaps i.e. it produces square waves for a short amount of time and then no waves for another short amount of time and then square waves again etc. However, this is not in a periodic fashion.
I'm not sure why the same code is producing the waves fine in terminal but not in Qt Creator. Any help would be greatly appreciated.

The way I am running both waves is through the use of threads to start and terminate each wave with the use of pushButtons. My code is below:

generates the square wave:
@static void generate_square(snd_pcm_uframes_t offset, int count, double *_phase)
{
static double max_phase = 2. * M_PI;
double phase = _phase;
double step = max_phasefreq/(double)rate;
unsigned char samples[channels];
int steps[channels];
unsigned int chn;
int format_bits = snd_pcm_format_width(format);
unsigned int maxval = (1 << (format_bits - 1)) - 1;
int bps = format_bits / 8; / bytes per sample */
int phys_bps = snd_pcm_format_physical_width(format) / 8;
int big_endian = snd_pcm_format_big_endian(format) == 1;
int to_unsigned = snd_pcm_format_unsigned(format) == 1;
int is_float = (format == SND_PCM_FORMAT_FLOAT_LE ||
format == SND_PCM_FORMAT_FLOAT_BE);
float amplitude_scale = ampl/8.56;
float a;
int b;

// verify and prepare the contents of areas
for (chn = 0; chn < channels; chn++) {

    if ((areas[chn].first % 8) != 0) {

                printf("areas[%i].first == %i, aborting...", chn , areas[chn].first);
                exit(EXIT_FAILURE);
        }
         samples[chn] = (((unsigned char *)areas[chn].addr) + (areas[chn].first / 8));


       if ((areas[chn].step % 16) != 0) {

              // printf("areas[%i].step == %i, aborting...  ", chn areas[chn].step);
               exit(EXIT_FAILURE);
       }
        steps[chn] = areas[chn].step / 8;
        samples[chn] += offset * steps[chn];


}
// fill the channel areas
while (count-- > 0) {
        union {
                float f;
                int i;
        } fval;
        int res, i;
        if (is_float) {
                a = amplitude_scale * sgn(sin(phase)) * maxval;
                fval.f = a;
                res = fval.i;
        } else {
                b = amplitude_scale * sgn(sin(phase)) * maxval;
                printf("b = %d\n",b);
                res = b;

        }

        if (to_unsigned)
                res ^= 1U << (format_bits - 1);
        for (chn = 0; chn < channels; chn++) {
                // Generate data in native endian format
                if (big_endian) {
                        for (i = 0; i < bps; i++)
                                *(samples[chn] + phys_bps - 1 - i) = (res >> i * 8) & 0xff;
                } else {
                        for (i = 0; i < bps; i++)
                                *(samples[chn] + i) = (res >>  i * 8) & 0xff;
                }
                samples[chn] += steps[chn];
        }
        phase += step;
        if (phase >= max_phase)
                phase -= max_phase;
}
*_phase = phase;

}@

produces/writes the square wave:
@void onWriteLoopSquare()
{

double phase = 0;
signed short *ptr;
int err, cptr;

generate_square(0, period_size, &phase);

while (1) {

    ptr = samples;
    cptr = period_size;
    while (cptr > 0) {
        err = snd_pcm_writei(hspdif, ptr, cptr);
    if (err == -EAGAIN)
        continue;
    if (err < 0) {
    if (xrun_recovery(hspdif, err) < 0) {
        printf("Write error: %s ", snd_strerror(err));
        exit(EXIT_FAILURE);
        }
    break; // skip one period
    }
ptr += err * channels;
cptr -= err;
}

}

}@

pushButton function:
@void wave::on_goSquare_clicked()
{
//Generate
freq = ui->squareFrequency->text().toDouble();
ampl = ui->squareAmplitude->text().toDouble();

squarethread->start();
ui->goSquare->setEnabled(false);
ui->goSquare->setStyleSheet("background-color: gray");
ui->stopSquare->setStyleSheet("background-color: rgb(255, 192, 192);"
                              "color: red;");
ui->stopSquare->setEnabled(true);

}

void wave::on_stopSquare_clicked()
{
//Terminate
squarethread->terminate();
ui->stopSquare->setEnabled(false);
ui->stopSquare->setStyleSheet("background-color: gray");
ui->goSquare->setStyleSheet("background-color: rgb(192, 255, 208);"
"color: green;");
ui->goSquare->setEnabled(true);
}@

ogopa

never mind. found my mistake. I took float a and int b out of my program so there were no delays assigning the calculations to fval.f and res in function generate_square()

mlong

I very seriously doubt that a delay assigning the calculations was causing the problems, but as long you have it working, great!

ogopa

[quote author="mlong" date="1313702759"]I very seriously doubt that a delay assigning the calculations was causing the problems, but as long you have it working, great!
[/quote]

Sorry, I did not know whether it caused a delay. I shouldn't have said that. What I meant to say was that, after assigning the calculations directly to fval.f and res, the gaps in my square wave disappeared. Like below:
@fval.f = amplitude_scale * sgn(sin(phase)) * maxval;
res = amplitude_scale * sgn(sin(phase)) * maxval;@

instead of :
@a = amplitude_scale * sgn(sin(phase)) * maxval;
fval.f = a;

b = amplitude_scale * sgn(sin(phase)) * maxval;
res = b;
@