Akso - Audio DSP Platform

APC7

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Author: Smashed Transistors

License: LGPL

Github: tiar/filter/APC7 .axo

Inlets

frac32buffer in

frac32 freq1

frac32 freq2

frac32 freq3

frac32 freq4

frac32 freq5

frac32 freq6

frac32 freq7

frac32 fb

Outlets

frac32buffer out

Declaration

class APC {
public:
  int32_t v[7];
  int32_t g[7];
  void init(void) {
    for (int i = 0; i < 7; i++)
      v[i] = 0;
  }
  int32_t aProc(int32_t x) {
    int32_t y = x;
    for (int p = 0; p < 7; p++) {
      int32_t u = ___SMMLA(g[p], v[p] << 1, y);
      y = ___SMMLS(g[p], u << 1, v[p]);
      v[p] = u;
    }
    return y;
  }
};
APC apc;
int32_t v;

Init

apc.init();
v = 0;

Control Rate

apc.g[0] = 0x7FFFFFFF - (__USAT(inlet_freq1, 27) << 4);
apc.g[1] = 0x7FFFFFFF - (__USAT(inlet_freq2, 27) << 4);
apc.g[2] = 0x7FFFFFFF - (__USAT(inlet_freq3, 27) << 4);
apc.g[3] = 0x7FFFFFFF - (__USAT(inlet_freq4, 27) << 4);
apc.g[4] = 0x7FFFFFFF - (__USAT(inlet_freq5, 27) << 4);
apc.g[5] = 0x7FFFFFFF - (__USAT(inlet_freq6, 27) << 4);
apc.g[6] = 0x7FFFFFFF - (__USAT(inlet_freq7, 27) << 4);
int32_t fb = __USAT((inlet_fb), 27) << 4; // q31

Audio Rate

// nested all pass chain
int32_t u = ___SMMLA(fb, v << 1, inlet_in);
outlet_out = ___SMMLS(fb, u << 1, v);
v = apc.aProc(u >> 8) << 8;

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