samples/risp4ml/common/utils.c

#include "samples/risp4ml/common/utils.h"

// int GetBayerIndex(int x, int y) {
//   // The Bayer pattern code defines which color is top left in the quad:
//   // +---+---+
//   // | R | Gr|
//   // +---+---+
//   // | Gb| B |
//   // +---+---+
//   return ((x & 1) + 2 * (y & 1));
// }

BayerIndex GetBayerIndex(BayerPattern bayerType, uint16_t x, uint16_t y) {
  // The Bayer pattern code defines which color is top left in the quad:
  // 0: +---+---+ 1: +---+---+ 2: +---+---+ 3: +---+---+
  //    | R | Gr|    | Gr| R |    | Gb| B |    | B | Gb|
  //    +---+---+    +---+---+    +---+---+    +---+---+
  //    | Gb| B |    | B | Gb|    | R | Gr|    | Gr| R |
  //    +---+---+    +---+---+    +---+---+    +---+---+
  // pattern 0 is base pattern and other patterns are shifted versions of the
  // base

  // Patterns 1 and 3 shift in the x
  uint16_t x_shift = (uint16_t)(bayerType == kGrbg || bayerType == kBggr);
  // Patterns 2 and 3 shift in the y
  uint16_t y_shift = (uint16_t)(bayerType == kGbrg || bayerType == kBggr);
  return (BayerIndex)(((x + x_shift) & 1) + 2 * ((y + y_shift) & 1));
}

int BayerMirrorBoundary(int x, int size) {
  if (x < 0)
    return (-x + 2 * (-x & 0x1) - 2);
  else if (x < size)
    return x;
  else
    return 2 * size - x - 2 * ((x - size + 1) & 0x1);
}