Function createFp

internal/diff.ts:188–218

(
  k: number,
  M: number,
  routes: Uint32Array,
  diffTypesPtrOffset: number,
  ptr: number,
  slide?: FarthestPoint,
  down?: FarthestPoint,
)

 * ```
 */
export function createFp(
  k: number,
  M: number,
  routes: Uint32Array,
  diffTypesPtrOffset: number,
  ptr: number,
  slide?: FarthestPoint,
  down?: FarthestPoint,
): FarthestPoint {
  if (slide && slide.y === -1 && down && down.y === -1) {
    return { y: 0, id: 0 };
  }
  const isAdding = (down?.y === -1) ||
    k === M ||
    (slide?.y ?? 0) > (down?.y ?? 0) + 1;
  if (slide && isAdding) {
    const prev = slide.id;
    ptr++;
    routes[ptr] = prev;
    routes[ptr + diffTypesPtrOffset] = ADDED;
    return { y: slide.y, id: ptr };
  }
  if (down && !isAdding) {
    const prev = down.id;
    ptr++;
    routes[ptr] = prev;
    routes[ptr + diffTypesPtrOffset] = REMOVED;
    return { y: down.y + 1, id: ptr };
  }
  throw new Error("Unexpected missing FarthestPoint");
}

/**
 * Renders the differences between the actual and expected values.