benchmark-memory-read.ino

#include <avr/pgmspace.h>
#include <EEPROM.h>

#define BUFFER_LEN 256

char sram_buffer[] = {
  170, 160, 146, 188, 90, 202, 109, 76, 120, 184, 232, 184, 109, 156, 246, 179, 19, 75, 56, 48, 91, 209, 200, 135, 191, 40, 119, 141, 202, 241, 223, 195, 115, 21, 79, 228, 99, 148, 66, 202, 146, 157, 71, 23, 190, 170, 173, 92, 191, 246, 187, 66, 94, 186, 2, 78, 135, 49, 211, 43, 187, 57, 56, 47, 197, 128, 49, 250, 230, 183, 77, 196, 185, 252, 46, 157, 225, 177, 23, 215, 167, 51, 233, 237, 108, 164, 185, 111, 180, 123, 126, 227, 239, 225, 191, 209, 236, 103, 196, 255, 0, 55, 99, 146, 15, 184, 198, 223, 116, 61, 88, 48, 10, 227, 39, 82, 179, 197, 61, 246, 147, 77, 95, 208, 245, 241, 118, 247, 139, 224, 134, 7, 48, 165, 15, 128, 157, 173, 96, 236, 182, 234, 84, 153, 21, 237, 38, 246, 198, 7, 216, 17, 43, 182, 228, 118, 195, 1, 13, 223, 243, 248, 40, 16, 237, 174, 195, 190, 102, 26, 21, 238, 97, 114, 183, 40, 82, 188, 207, 197, 23, 164, 38, 129, 222, 242, 34, 244, 148, 8, 224, 184, 52, 5, 66, 134, 100, 143, 204, 213, 22, 219, 193, 103, 210, 249, 81, 41, 206, 130, 46, 190, 238, 105, 142, 9, 197, 30, 142, 172, 133, 193, 104, 101, 255, 63, 240, 147, 177, 237, 48, 117, 149, 152, 126, 78, 125, 40, 63, 52, 2, 255, 64, 80, 32, 94, 98, 114, 202, 51, 112, 72, 95, 209, 79, 44
};

const char progmem_buffer[] PROGMEM = {
  170, 160, 146, 188, 90, 202, 109, 76, 120, 184, 232, 184, 109, 156, 246, 179, 19, 75, 56, 48, 91, 209, 200, 135, 191, 40, 119, 141, 202, 241, 223, 195, 115, 21, 79, 228, 99, 148, 66, 202, 146, 157, 71, 23, 190, 170, 173, 92, 191, 246, 187, 66, 94, 186, 2, 78, 135, 49, 211, 43, 187, 57, 56, 47, 197, 128, 49, 250, 230, 183, 77, 196, 185, 252, 46, 157, 225, 177, 23, 215, 167, 51, 233, 237, 108, 164, 185, 111, 180, 123, 126, 227, 239, 225, 191, 209, 236, 103, 196, 255, 0, 55, 99, 146, 15, 184, 198, 223, 116, 61, 88, 48, 10, 227, 39, 82, 179, 197, 61, 246, 147, 77, 95, 208, 245, 241, 118, 247, 139, 224, 134, 7, 48, 165, 15, 128, 157, 173, 96, 236, 182, 234, 84, 153, 21, 237, 38, 246, 198, 7, 216, 17, 43, 182, 228, 118, 195, 1, 13, 223, 243, 248, 40, 16, 237, 174, 195, 190, 102, 26, 21, 238, 97, 114, 183, 40, 82, 188, 207, 197, 23, 164, 38, 129, 222, 242, 34, 244, 148, 8, 224, 184, 52, 5, 66, 134, 100, 143, 204, 213, 22, 219, 193, 103, 210, 249, 81, 41, 206, 130, 46, 190, 238, 105, 142, 9, 197, 30, 142, 172, 133, 193, 104, 101, 255, 63, 240, 147, 177, 237, 48, 117, 149, 152, 126, 78, 125, 40, 63, 52, 2, 255, 64, 80, 32, 94, 98, 114, 202, 51, 112, 72, 95, 209, 79, 44
};

unsigned int benchmark_sram() {
  unsigned int checksum = 0;

  for (int i = 0; i < BUFFER_LEN; i++) {
    checksum += (unsigned char)sram_buffer[i];
  }

  return checksum;
}

unsigned int benchmark_progmem() {
  unsigned int checksum = 0;

  for (int i = 0; i < BUFFER_LEN; i++) {
    checksum += (unsigned char)pgm_read_byte_near(progmem_buffer + i);
  }

  return checksum;
}

// not sure what is currently in eeprom, and arduino flash strips this section
// from binary, so need to initialise this manually ... once
void setup_eeprom() {
  for (int i = 0; i < BUFFER_LEN; i++) {
    EEPROM.write(i, sram_buffer[i]);
  }
}

unsigned int benchmark_eeprom() {
  unsigned int checksum = 0;

  for (int i = 0; i < BUFFER_LEN; i++) {
    checksum += (unsigned char)EEPROM.read(i);
  }

  return checksum;
}

void setup() {
  Serial.begin(9600);

  unsigned long sram_start = micros();
  int sram_csum = benchmark_sram();
  unsigned long sram_end = micros();

  unsigned long progmem_start = micros();
  int progmem_csum = benchmark_progmem();
  unsigned long progmem_end = micros();

  setup_eeprom(); 
  unsigned long eeprom_start = micros();
  int eeprom_csum = benchmark_eeprom();
  unsigned long eeprom_end = micros();

  // dump sram stats
  Serial.println("sram:");
  Serial.print("- checksum:");
  Serial.println(sram_csum, HEX);
  Serial.print("- time:");
  Serial.println(sram_end - sram_start);

  // dump progmem stats
  Serial.println("progmem:");
  Serial.print("- checksum:");
  Serial.println(progmem_csum, HEX);
  Serial.print("- time:");
  Serial.println(progmem_end - progmem_start);

  // dump eeprom stats
  Serial.println("eeprom:");
  Serial.print("- checksum:");
  Serial.println(eeprom_csum, HEX);
  Serial.print("- time:");
  Serial.println(eeprom_end - eeprom_start);
}

void loop() {
}