A more flexible XY() mapping function for FastLED

flexible_XY_mapper.ino

#define kMatrixWidth      16
#define kMatrixHeight     16
#define kMatrixSerpentine true
#define kMatrixRowMajor   true
#define kMatrixFlipMajor  true
#define kMatrixFlipMinor  false

#define NUM_LEDS ((kMatrixWidth) * (kMatrixHeight))
CRGB leds[NUM_LEDS + 1];  // 1 extra for XY() to use when out-of-bounds

uint16_t XY(uint8_t x, uint8_t y) {
  uint8_t major, minor, sz_major, sz_minor;
  if (x >= kMatrixWidth || y >= kMatrixHeight) return NUM_LEDS;
  if (kMatrixRowMajor)
    major = x, minor = y, sz_major = kMatrixWidth,  sz_minor = kMatrixHeight;
  else
    major = y, minor = x, sz_major = kMatrixHeight, sz_minor = kMatrixWidth;
  if (kMatrixFlipMajor ^ (minor & 1 && kMatrixSerpentine))
    major = sz_major - 1 - major;
  if (kMatrixFlipMinor)
    minor = sz_minor - 1 - minor;
  return (uint16_t) minor * sz_major + major;
}