cdf53.h

/*
Reversible integer Cohen–Daubechies–Feauveau 5/3 wavelet

Copyright 2024 Ahmet Inan <xdsopl@gmail.com>
*/

#pragma once

void cdf53(int *out, int *in, int N, int SO, int SI, int CH)
{
	int M = N & ~1, K = N + (N & 1);
	for (int i = 1; i < N - 1; i += 2)
		for (int c = 0; c < CH; ++c)
			in[i * SI + c] -= (in[(i - 1) * SI + c] + in[(i + 1) * SI + c]) / 2;
	if (!(N & 1))
		for (int c = 0; c < CH; ++c)
			in[(N - 1) * SI + c] -= in[(N - 2) * SI + c];

	for (int c = 0; c < CH; ++c)
		in[c] += in[SI + c] / 2;
	for (int i = 2; i < M; i += 2)
		for (int c = 0; c < CH; ++c)
			in[i * SI + c] += (in[(i - 1) * SI + c] + in[(i + 1) * SI + c]) / 4;

	for (int i = 0; i < M; i += 2) {
		for (int c = 0; c < CH; ++c) {
			out[(i + 0) / 2 * SO + c] = in[(i + 0) * SI + c];
			out[(i + K) / 2 * SO + c] = in[(i + 1) * SI + c];
		}
	}
	if (N & 1)
		for (int c = 0; c < CH; ++c)
			out[(N - 1) / 2 * SO + c] = in[(N - 1) * SI + c];
}

void icdf53(int *out, int *in, int N, int SO, int SI, int CH)
{
	int M = N & ~1, K = N + (N & 1);
	for (int i = 0; i < M; i += 2) {
		for (int c = 0; c < CH; ++c) {
			out[(i + 0) * SO + c] = in[(i + 0) / 2 * SI + c];
			out[(i + 1) * SO + c] = in[(i + K) / 2 * SI + c];
		}
	}
	if (N & 1)
		for (int c = 0; c < CH; ++c)
			out[(N - 1) * SO + c] = in[(N - 1) / 2 * SI + c];

	for (int c = 0; c < CH; ++c)
		out[c] -= out[SO + c] / 2;
	for (int i = 2; i < M; i += 2)
		for (int c = 0; c < CH; ++c)
			out[i * SO + c] -= (out[(i - 1) * SO + c] + out[(i + 1) * SO + c]) / 4;

	for (int i = 1; i < N - 1; i += 2)
		for (int c = 0; c < CH; ++c)
			out[i * SO + c] += (out[(i - 1) * SO + c] + out[(i + 1) * SO + c]) / 2;
	if (!(N & 1))
		for (int c = 0; c < CH; ++c)
			out[(N - 1) * SO + c] += out[(N - 2) * SO + c];
}