Unable to call .first of array[SOLVED]
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Hi guys,
I have two problems:
Problem number 1: I am using pcm.c to build a gui to generate sine waves using user input. I have integrated the code into Qt Creator and I compiled and ran the code with no errors.
However, every time I click the pushButton (which is supposed to output the sine wave), my program terminates. I have tracked the problem code. In my pushButton function, I have called a function called write_loop which calls generate_sine(). This is causing the problem. I have debugged the code in generate_sine() and I found out that the line which causes it to terminate is this one:
@if ((areas[chn].first % 8) != 0) {
printf("areas[%i].first == %i, aborting...", chn , areas[chn].first);
exit(EXIT_FAILURE);
}@
I found out that the problem is that it is refusing to use this specific code: @areas[chn].first@. Also, I did a check to see areas[chn].first is divisible by 8 and it is for all the values of chn. THis program seems only to have the problem of calling areas[chn].first. I have found the problem, but now I don't know how to fix it. Any help would be greatly appreciated.The code I have under my pushButton function(on_pushButton_clicked) and generate_sine.cpp is shown below.
generate_sine.cpp:
@void generate_sine(snd_pcm_channel_area_t *areas,
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 = amplitude/8.56;// verify and prepare the contents of areas for (chn = 0; chn < channels; chn++) { if (areas[chn].first!=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 !=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) { fval.f = amplitude_scale * sin(phase) * maxval; res = fval.i; } else res = amplitude_scale * sin(phase) * maxval; 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;}@
more code posted below because of word limit -
on_pushButton_clicked():
@void wave::on_pushButton_clicked()
{struct transfer_method { const char *name; snd_pcm_access_t access; int (*transfer_loop)(snd_pcm_t *handle, signed short *samples, snd_pcm_channel_area_t *areas); }; static struct transfer_method transfer_methods[] = { { "write", SND_PCM_ACCESS_RW_INTERLEAVED, write_loop }, { NULL, SND_PCM_ACCESS_RW_INTERLEAVED, NULL } }; snd_pcm_t *handle; int err; snd_pcm_hw_params_t *hwparams; snd_pcm_sw_params_t *swparams; int method = 0; signed short *samples; unsigned int chn; snd_pcm_channel_area_t *areas; snd_pcm_hw_params_alloca(&hwparams); snd_pcm_sw_params_alloca(&swparams); err = snd_output_stdio_attach(&output, stdout, 0); if (err < 0) { printf("Output failed: %s" , snd_strerror(err)); } if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) { printf("Playback open error: %s", snd_strerror(err)); } if ((err = set_hwparams(handle, hwparams, transfer_methods[method].access)) < 0) { printf("Setting of hwparams failed: %s", snd_strerror(err)); exit(EXIT_FAILURE); } if ((err = set_swparams(handle, swparams)) < 0) { printf("Setting of swparams failed: %s", snd_strerror(err)); exit(EXIT_FAILURE); } if (verbose > 0) snd_pcm_dump(handle, output); samples = new signed short [period_size * channels * snd_pcm_format_physical_width(format)]; if (samples == NULL) { printf("Not enough memory"); exit(EXIT_FAILURE); } areas = new snd_pcm_channel_area_t [channels]; if (areas == NULL) { printf("Not enough memory"); exit(EXIT_FAILURE); } for (chn = 0; chn < channels; chn++) { areas[chn].addr = samples; areas[chn].first = chn * snd_pcm_format_physical_width(format); areas[chn].step = channels * snd_pcm_format_physical_width(format); } err = transfer_methods[method].transfer_loop(handle, samples, areas); delete [] areas; delete []samples; snd_pcm_close(handle);}@
Problem number 2:
When I set my while loop in the write_loop function to 'true', i.e while(isTrue), (when bool isTrue = true; is defined at the top), my program immediately terminates. And to make sure that it isn't the generate_sine() function that isn't doing it(as described above, I commented the generate_sine() function out, and it still just terminates. However, If I don't set any value for bool isTrue (i.e. just define bool isTrue; at the top, the program doesn't terminate.
Here is my write_loop function:
@int write_loop(snd_pcm_t *device_handle,
signed short *samples,
snd_pcm_channel_area_t *areas)
{
double phase = 0;
signed short *ptr;
int err, cptr;generate_sine(areas, 0, period_size, &phase); while (isTrue) { ptr = samples; cptr = period_size; while (cptr > 0) { err = snd_pcm_writei(device_handle, ptr, cptr); if (err == -EAGAIN) continue; if (err < 0) { if (xrun_recovery(device_handle, err) < 0) { printf("Write error: %s ", snd_strerror(err)); exit(EXIT_FAILURE); } break; // skip one period } ptr += err * channels; cptr -= err; } }}
@ -
solved. areas had different values as it was declared again.