128 lines
5 KiB
Rust
128 lines
5 KiB
Rust
// nih-plug: plugins, but rewritten in Rust
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// Copyright (C) 2022 Robbert van der Helm
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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/// The audio buffers used during processing. This contains the output audio output buffers with the
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/// inputs already copied to the outputs. You can either use the iterator adapters to conveniently
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/// and efficiently iterate over the samples, or you can do your own thing using the raw audio
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/// buffers.
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#[derive(Default)]
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pub struct Buffer<'a> {
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/// Contains slices for the plugin's outputs. You can't directly create a nested slice form
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/// apointer to pointers, so this needs to be preallocated in the setup call and kept around
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/// between process calls. And because storing a reference to this means a) that you need a lot
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/// of lifetime annotations everywhere and b) that at some point you need unsound lifetime casts
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/// because this `Buffers` either cannot have the same lifetime as the separately stored output
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/// buffers, and it also cannot be stored in a field next to it because that would mean
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/// containing mutable references to data stored in a mutex.
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output_slices: Vec<&'a mut [f32]>,
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}
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impl<'a> Buffer<'a> {
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/// Returns true if this buffer does not contain any samples.
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pub fn is_empty(&self) -> bool {
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self.output_slices.is_empty() || self.output_slices[0].is_empty()
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}
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/// Obtain the raw audio buffers.
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pub fn as_raw(&mut self) -> &mut [&'a mut [f32]] {
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&mut self.output_slices
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}
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/// Iterate over the samples, returning a channel iterator for each sample.
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pub fn iter_mut(&mut self) -> Samples<'_, 'a> {
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Samples {
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buffers: &mut self.output_slices,
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current_sample: 0,
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}
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}
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/// Access the raw output slice vector. This neds to be resized to match the number of output
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/// channels during the plugin's initialization. Then during audio processing, these slices
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/// should be updated to point to the plugin's audio buffers.
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///
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/// # Safety
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///
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/// The stored slices must point to live data when this object is passed to the plugins' process
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/// function. The rest of this object also assumes all channel lengths are equal. Panics will
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/// likely occur if this is not the case.
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pub unsafe fn as_raw_vec(&mut self) -> &mut Vec<&'a mut [f32]> {
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&mut self.output_slices
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}
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}
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/// An iterator over all samples in the buffer, yielding iterators over each channel for every
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/// sample. This iteration order offers good cache locality for per-sample access.
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pub struct Samples<'outer, 'inner> {
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/// The raw output buffers.
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pub(self) buffers: &'outer mut [&'inner mut [f32]],
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pub(self) current_sample: usize,
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}
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impl<'outer, 'inner> Iterator for Samples<'outer, 'inner> {
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type Item = Channels<'outer, 'inner>;
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fn next(&mut self) -> Option<Self::Item> {
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if self.current_sample < self.buffers[0].len() {
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// SAFETY: We guarantee that each sample is only mutably borrowed once in the channels
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// iterator
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let buffers: &'outer mut _ = unsafe { &mut *(self.buffers as *mut _) };
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let channels = Channels {
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buffers,
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current_sample: self.current_sample,
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current_channel: 0,
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};
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self.current_sample += 1;
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Some(channels)
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} else {
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None
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}
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}
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}
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/// An iterator over the channel data for a sample, yielded by [Samples].
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pub struct Channels<'outer, 'inner> {
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/// The raw output buffers.
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pub(self) buffers: &'outer mut [&'inner mut [f32]],
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pub(self) current_sample: usize,
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pub(self) current_channel: usize,
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}
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impl<'outer, 'inner> Iterator for Channels<'outer, 'inner> {
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type Item = &'inner mut f32;
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fn next(&mut self) -> Option<Self::Item> {
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if self.current_channel < self.buffers.len() {
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// SAFETY: These bounds have already been checked
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let sample = unsafe {
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self.buffers
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.get_unchecked_mut(self.current_channel)
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.get_unchecked_mut(self.current_sample)
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};
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// SAFETY: It is not possible to have multiple mutable references to the same sample at
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// the same time
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let sample: &'inner mut f32 = unsafe { &mut *(sample as *mut f32) };
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self.current_channel += 1;
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Some(sample)
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} else {
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None
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}
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}
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}
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