Akso - Audio DSP Platform

Declaration

int32_t inbuf[128];
int32_t outbuf[128];
int32_t fftbuf[256];
int32_t hanning_q31[128];
arm_rfft_instance_q31 rfft;
arm_cfft_radix4_instance_q31 cfft;
int32_t state;
msg_t ThreadX2() {
  int i;
  int n = 128;
  arm_rfft_init_q31(&rfft, 128, 0, 1);
  for (i = 0; i < n; i++) {
    hanning_q31[i] =
        (int32_t)(0.5f * 2147483647.0f * (1.0f - cosf(2.0f * PI * i / n)));
  }
  while (!chThdShouldTerminate()) {
    chThdSleepMilliseconds(20);
    if (state == 128) {
      arm_mult_q31(hanning_q31, &inbuf[0], &inbuf[0], n);
      arm_rfft_q31(&rfft, &inbuf[0], &fftbuf[0]);
      arm_cmplx_mag_q31(&fftbuf[0], outbuf, n / 2);
      // reduce to packed 8bit
      for (i = 0; i < n / 8; i++) {
        int32_t ni;
        uint8_t *nc;
        nc = (uint8_t *)&ni;
        nc[0] = 0xFF & (outbuf[i * 4] >> 19);
        nc[1] = 0xFF & (outbuf[i * 4 + 1] >> 19);
        nc[2] = 0xFF & (outbuf[i * 4 + 2] >> 19);
        nc[3] = 0xFF & (outbuf[i * 4 + 3] >> 19);
        outbuf[i] = ni;
      }
      state = 129;
    }
  }
}
static msg_t ThreadX(void *arg) { ((attr_parent *)arg)->ThreadX2(); }
WORKING_AREA(waThreadX, 4096);
Thread *Thd;

Init

int i;
for (i = 0; i < 128; i++)
  inbuf[i] = 0;
for (i = 0; i < 128; i++)
  outbuf[i] = 0;
state = 0;
Thd = chThdCreateStatic(waThreadX, sizeof(waThreadX), NORMALPRIO, ThreadX,
                        (void *)this);

Control Rate

if (state < 128) {
  int i;
  for (i = 0; i < 16; i++)
    inbuf[state++] = inlet_in[i];
} else if (state == 129) {
  state = 0;
  if (!inlet_hold) {
    disp_v0 = outbuf[0];
    disp_v1 = outbuf[1];
    disp_v2 = outbuf[2];
    disp_v3 = outbuf[3];
    disp_v4 = outbuf[4];
    disp_v5 = outbuf[5];
    disp_v6 = outbuf[6];
    disp_v7 = outbuf[7];
    disp_v8 = outbuf[8];
    disp_v9 = outbuf[9];
    disp_v10 = outbuf[10];
    disp_v11 = outbuf[11];
    disp_v12 = outbuf[12];
    disp_v13 = outbuf[13];
    disp_v14 = outbuf[14];
    disp_v15 = outbuf[15];
  }
}

Dispose

chThdTerminate(Thd);

rfft 128

spectral analyzer display using 128 input points fft

Author: Johannes Taelman

License: BSD

Github: spectral/rfft 128.axo

Inlets

Outlets

Displays