// https://forum.arduino.cc/t/direct-addressing-to-the-arduino-flash-memory/1016070

#include <EEPROM.h>

typedef uint8_t (* memf_t)(uint32_t const);


uint8_t readMem(uint32_t const index) {
  char const* mem = 0;
  return mem[index];
}

uint8_t readFlash(uint32_t const index) {
#ifdef pgm_read_byte_far
  return pgm_read_byte_far(index);
#else
  return pgm_read_byte(index);
#endif
}

uint8_t readEEPROM(uint32_t const index) {
  return EEPROM.read(index);
}


char printable(uint8_t const x) {
  if (x < 32 or x > 126) {
    return '.';
  }
  return x;
}

void dumpLine(char line[], memf_t const f, uint32_t const offset) {
  sprintf(line, "%06lx  ", offset);
  for (uint32_t i = 0; i < 16; i++) {
    sprintf(line + strlen(line), "%02x ", f(offset + i));
  }
  sprintf(line + strlen(line), " ");
  for (uint32_t i = 0; i < 16; i++) {
    sprintf(line + strlen(line), "%c", printable(f(offset + i)));
  }
}

void dumpBlock(Stream& out, memf_t const f, uint32_t const offset, uint32_t const size) {
  for (uint32_t i = offset; i < offset + size; i += 16) {
    char line[74];
    dumpLine(line, f, i);
    out.println(line);
  }
}


void setup() {
  Serial.begin(115200);

  Serial.println("EEPROM");
  dumpBlock(Serial, readEEPROM, 0, 16);     // 1024 max.

  Serial.println("\r\n\nMemory");
  dumpBlock(Serial, readMem, 0, 1280);      // 8192 max.

  Serial.println("\r\n\nFLASH");
  dumpBlock(Serial, readFlash, 0, 4096);  // 262144 max.
}

void loop() {}