FileLoop.h

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#pragma once
 
#include "AudioTools/CoreAudio/BaseStream.h"
#include "AudioTools/CoreAudio/AudioBasic/StrView.h"
#ifdef ARDUINO
#  include "FS.h"
#  define READTYPE char
#else 
#  define READTYPE uint8_t
#endif
namespace audio_tools {
 
template <class FileType> class FileLoopT : public BaseStream {
public:
  FileLoopT() = default;
  FileLoopT(FileType file, int count = -1, int rewindPos = -1, int startPos = 0) {
    setFile(file);
    setLoopCount(count);
    setRewindPos(rewindPos);
    setStartPos(startPos);
  }
 
  // restarts the file from the beginning
  bool begin()  {
    TRACEI();
    // automatic determination of rewind pos
    if (rewind_pos <= 0){
      current_file.seek(0);
      char tmp[5] = {0};
      current_file.readBytes(tmp, 4);
      // for wav files remove header
      rewind_pos = StrView(tmp).equals("RIFF") ? 44 : 0;
    }
    current_file.seek(start_pos);
    size_open = total_size;
    return current_file;
  }
 
  // closes the file
  void end()  { 
    TRACEI();
    current_file.close(); 
  }
 
  void setFile(FileType file) { this->current_file = file; }
 
  FileType &file(){
    return current_file;
  }
 
  void setRewindPos(int pos) { rewind_pos = pos; }
 
  void setStartPos(int pos) { start_pos = pos; }
 
  void setSize(size_t len) {
    total_size = len;
  }
 
  size_t size() {
    return total_size == -1 ? current_file.size() : total_size;
  }
 
  void setCallback(void (*cb)(FileLoopT &loop)){
    callback = cb;
  }
 
  void setLoopCount(int count) { loop_count = count; }
 
  int available() override {
    // if we manage the size, we return the open amount
    if (total_size!=-1) return size_open;
    // otherwise we return DEFAULT_BUFFER_SIZE if looping is active
    return isLoopActive() ? DEFAULT_BUFFER_SIZE : current_file.available();
  }
 
  size_t readBytes(uint8_t *data, size_t len) override {
    LOGD("FileLoopT::readBytes %d at %d", (int)len, (int)current_file.position());
    if (!current_file)
      return 0;
    
    // limit the copy size if necessary
    int copy_len = len;
    if (total_size!=-1){
      copy_len = min((int)len, size_open);
    }
 
    // read step 1;
    int result1 = current_file.readBytes((READTYPE *)data, copy_len);
    int result2 = 0;
    int open = copy_len - result1;
    if (isLoopActive() && open > 0) {
      if (rewind_pos < 0) rewind_pos = 0;
      LOGI("seek %d", rewind_pos);
      // looping logic -> rewind to beginning: read step 2
      current_file.seek(rewind_pos);
      // notify user
      if (callback!=nullptr){
        callback(*this);
      }
      result1 = current_file.readBytes((READTYPE*)data + result1, open);
      if (loop_count>0)
        loop_count--;
    }
    // determine the result size
    int result = result1 + result2;
    // calculate the size_open if necessary
    if (total_size!=-1){
      size_open -= result;
    }
    return result;
  }
 
  // Returns the bool of the current file
  operator bool() {
    return current_file;
  }
 
  bool isLoopActive() { return loop_count > 0 || loop_count == -1; }
 
  size_t write(const uint8_t* data, size_t len) { return current_file.write(data, len);}
 
protected:
  int rewind_pos = -1;
  int start_pos = 0;
  int loop_count = -1;
  int size_open = -1;
  int total_size = -1;
  void (*callback)(FileLoopT &loop) = nullptr;
  FileType current_file;
};
 
class FileLoop : public FileLoopT<File> {
public:
  FileLoop() = default;
  FileLoop(File file, int count = -1, int rewindPos = 0)
      : FileLoopT<File>(file, count, rewindPos) {}
};
 
} // namespace audio_tools