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use rustfft::num_complex::Complex;
use rustfft::Length;
use twiddles;
use ::{DCT2, DST2, DCT3, DST3, TransformType2And3};
use common;
pub struct Type2And3Naive<T> {
twiddles: Box<[Complex<T>]>,
}
impl<T: common::DCTnum> Type2And3Naive<T> {
pub fn new(len: usize) -> Self {
let twiddles: Vec<Complex<T>> = (0..len * 4)
.map(|i| twiddles::single_twiddle(i, len * 4))
.collect();
Type2And3Naive { twiddles: twiddles.into_boxed_slice() }
}
}
impl<T: common::DCTnum> DCT2<T> for Type2And3Naive<T> {
fn process_dct2(&self, input: &mut [T], output: &mut [T]) {
common::verify_length(input, output, self.len());
for k in 0..output.len() {
let output_cell = output.get_mut(k).unwrap();
*output_cell = T::zero();
let twiddle_stride = k * 2;
let mut twiddle_index = k;
for i in 0..input.len() {
let twiddle = self.twiddles[twiddle_index];
*output_cell = *output_cell + input[i] * twiddle.re;
twiddle_index += twiddle_stride;
if twiddle_index >= self.twiddles.len() {
twiddle_index -= self.twiddles.len();
}
}
}
}
}
impl<T: common::DCTnum> DST2<T> for Type2And3Naive<T> {
fn process_dst2(&self, input: &mut [T], output: &mut [T]) {
common::verify_length(input, output, self.len());
for k in 0..output.len() {
let output_cell = output.get_mut(k).unwrap();
*output_cell = T::zero();
let twiddle_stride = (k + 1) * 2;
let mut twiddle_index = k + 1;
for i in 0..input.len() {
let twiddle = self.twiddles[twiddle_index];
*output_cell = *output_cell - input[i] * twiddle.im;
twiddle_index += twiddle_stride;
if twiddle_index >= self.twiddles.len() {
twiddle_index -= self.twiddles.len();
}
}
}
}
}
impl<T: common::DCTnum> DCT3<T> for Type2And3Naive<T> {
fn process_dct3(&self, input: &mut [T], output: &mut [T]) {
common::verify_length(input, output, self.len());
let half_first = T::half() * input[0];
for k in 0..output.len() {
let output_cell = output.get_mut(k).unwrap();
*output_cell = half_first;
let twiddle_stride = k * 2 + 1;
let mut twiddle_index = twiddle_stride;
for i in 1..input.len() {
let twiddle = self.twiddles[twiddle_index];
*output_cell = *output_cell + input[i] * twiddle.re;
twiddle_index += twiddle_stride;
if twiddle_index >= self.twiddles.len() {
twiddle_index -= self.twiddles.len();
}
}
}
}
}
impl<T: common::DCTnum> DST3<T> for Type2And3Naive<T> {
fn process_dst3(&self, input: &mut [T], output: &mut [T]) {
common::verify_length(input, output, self.len());
input[input.len() - 1] = input[input.len() - 1] * T::half();
for k in 0..output.len() {
let output_cell = output.get_mut(k).unwrap();
*output_cell = T::zero();
let twiddle_stride = k * 2 + 1;
let mut twiddle_index = twiddle_stride;
for i in 0..input.len() {
let twiddle = self.twiddles[twiddle_index];
*output_cell = *output_cell - input[i] * twiddle.im;
twiddle_index += twiddle_stride;
if twiddle_index >= self.twiddles.len() {
twiddle_index -= self.twiddles.len();
}
}
}
}
}
impl<T: common::DCTnum> TransformType2And3<T> for Type2And3Naive<T>{}
impl<T> Length for Type2And3Naive<T> {
fn len(&self) -> usize {
self.twiddles.len() / 4
}
}