// samples should be u-law encoded
void modem_decode(buffer_t *input, buffer_t *output)
{
static int phase = -1;
int max_idx;
size_t i;
int16_t max_mag;
int16_t samples[SAMPLES_PER_ITER];
for (i = 0; i < SAMPLES_PER_ITER; i++)
{
uint8_t byte;
buffer_read_bytes(input, &byte, 1);
samples[i] = comp_decode(byte) * 4;
}
// apply band-pass filter to remove noise
bandpass_filter(samples);
// apply convolution with delay line
convolution(samples);
// apply low-pass filter to remove high-frequency artifacts
lowpass_filter(samples);
// try and find the middle of the phase
if (phase == -1)
{
max_mag = 0;
max_idx = 0;
for (i = 0; i < SAMPLES_PER_ITER; i++)
{
if (samples[i] > max_mag)
{
max_mag = samples[i];
max_idx = i;
}
else if (-samples[i] > max_mag)
{
max_mag = -samples[i];
max_idx = i;
}
}
phase = (max_idx) % (SAMPLES_PER_BIT / 2);
}
// sample at baudrate to get output
for (i = phase; i < SAMPLES_PER_ITER; i += SAMPLES_PER_BIT)
{
int avg = 0;
int j;
for (j = 0; j < SAMPLES_PER_BIT / 4; j++)
avg += samples[i + j]; //< 0 ? -1 : 1;
avg /= SAMPLES_PER_BIT / 4;
int bit = avg < 0 ? 1 : 0;
buffer_write_bit(output, bit);
}
}
int main(int argc, char *argv[])
{
int i, j, m, n;
double tempo_kernel;
double tempo_total;
char *output_filename;
float *image_amplitudes;
float (*x)[2];
float (*X)[2];
pgm_t ipgm, opgm;
image_file_t *image_filename;
timer_reset();
timer_start();
if (argc < 2)
{
printf("**Erro: parametros de entrada invalidos");
exit(EXIT_FAILURE);
}
image_filename = (image_file_t *) malloc(sizeof(image_file_t));
split_image_filename(image_filename, argv[1]);
output_filename = (char *) malloc(40*sizeof(char));
sprintf(output_filename, "%d.%d.%s.%s.%s", image_filename->res, image_filename->num, ENV_TYPE, APP_TYPE, EXTENSAO);
if( ler_pgm(&ipgm, argv[1]) == -1)
exit(EXIT_FAILURE);
n = ipgm.width;
m = (int)(log((double)n)/log(2.0));
x = malloc(2 * n * n * sizeof(float));
X = malloc(2 * n * n * sizeof(float));
opgm.width = n;
opgm.height = n;
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
x[i*n + j][0] = (float) ipgm.buf[i*n + j];
x[i*n + j][1] = (float) 0;
}
}
/* Check that n = 2^m for some integer m >= 1. */
if (n >= 2) {
i = n;
while(i==2*(i/2)) i = i/2; /* While i is even, factor out a 2. */
} /* For n >=2, we now have N = 2^n iff i = 1. */
if (n < 2 || i != 1) {
printf(" %d deve ser um inteiro tal que n = 2^m , para m >= 1", n);
exit(EXIT_FAILURE);
}
timer_stop();
tempo_total = get_elapsed_time();
//====== Performance Test - start =======================================
timer_reset();
timer_start();
j = 0;
j = n*n;
//fft direta
fft(j, x, X);
// filtro passa baixa
lowpass_filter(X, n);
//fft inversa
for(i=0; i<j; i++) x[i][0] = x[i][1] = 0;
ifft(j, x, X);
timer_stop();
tempo_kernel = get_elapsed_time();
tempo_total += tempo_kernel;
//====== Performance Test - end ============================================
save_log_cpu(image_filename, tempo_kernel, tempo_total, LOG_NAME);
image_amplitudes = (float*)malloc(n*n*sizeof(float));
for (i=0; i < n; i++) {
for (j=0; j < n; j++) {
image_amplitudes[i*n + j] = (float) (AMP(x[i*n + j][0], x[i*n + j][1]));
}
}
normalizar_pgm(&opgm, image_amplitudes);
escrever_pgm(&opgm, output_filename);
free(x);
free(X);
destruir_pgm(&ipgm);
destruir_pgm(&opgm);
free(image_filename);
free(output_filename);
free(image_amplitudes);
_CrtDumpMemoryLeaks();
return 0;
}
