DTMF.h

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#pragma once
 
#include <ctype.h>
#include <stdint.h>
#include <string.h>
 
#include "AudioTools.h"
 
namespace tinymodem {

struct DTMFConfig : public audio_tools::AudioInfo {
  DTMFConfig() {
    sample_rate = 48000;
    channels = 1;
    bits_per_sample = 16;
  }

  int tone_ms = 70;
  int pause_ms = 70;
  int comma_ms = 500;
  float volume = 1.0f;
  float min_amplitude = 0.01f;
  float max_twist_db = 16.0f;
  float group_ratio_db = 6.0f;
  int rx_timeout_ms = 250;
  bool rx_one = false;
  uint8_t channel = 0;
  float rx_noise = 0.0f;

  bool setMode(const char* mode) { return isMode(mode); }

  static bool isMode(const char* mode) {
    if (mode == nullptr) return false;
    const char* name = "dtmf";
    for (int j = 0; j < 5; j++)
      if (tolower(mode[j]) != name[j]) return false;
    return true;
  }

  bool isValid() const {
    if (tone_ms <= 0 || pause_ms <= 0 || comma_ms < 0 || rx_timeout_ms <= 0 ||
        max_twist_db <= 0 || group_ratio_db <= 0) {
      LOGE("DTMF: invalid durations");
      return false;
    }
    if (sample_rate < 4000) {
      LOGE("DTMF: the sample rate must be at least 4000 Hz");
      return false;
    }
    return true;
  }
};

class DTMFKeys {
 public:
  static const float* rows() {
    static const float freqs[4] = {697.0f, 770.0f, 852.0f, 941.0f};
    return freqs;
  }

  static const float* columns() {
    static const float freqs[4] = {1209.0f, 1336.0f, 1477.0f, 1633.0f};
    return freqs;
  }

  static char key(int row, int column) { return keys()[row * 4 + column]; }

  static bool find(char ch, int& row, int& column) {
    ch = toupper((unsigned char)ch);
    const char* pos = ch == 0 ? nullptr : strchr(keys(), ch);
    if (pos == nullptr) return false;
    int idx = pos - keys();
    row = idx / 4;
    column = idx % 4;
    return true;
  }
 
 protected:
  static const char* keys() { return "123A456B789C*0#D"; }
};
 
}  // namespace tinymodem