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Diffstat (limited to 'vendor/exr/src/compression/mod.rs')
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diff --git a/vendor/exr/src/compression/mod.rs b/vendor/exr/src/compression/mod.rs new file mode 100644 index 0000000..6869fdf --- /dev/null +++ b/vendor/exr/src/compression/mod.rs @@ -0,0 +1,666 @@ + +//! Contains the compression attribute definition +//! and methods to compress and decompress data. + + +// private modules make non-breaking changes easier +mod zip; +mod rle; +mod piz; +mod pxr24; +mod b44; + + +use std::convert::TryInto; +use std::mem::size_of; +use half::f16; +use crate::meta::attribute::{IntegerBounds, SampleType, ChannelList}; +use crate::error::{Result, Error, usize_to_i32}; +use crate::meta::header::Header; + + +/// A byte vector. +pub type ByteVec = Vec<u8>; + +/// A byte slice. +pub type Bytes<'s> = &'s [u8]; + +/// Specifies which compression method to use. +/// Use uncompressed data for fastest loading and writing speeds. +/// Use RLE compression for fast loading and writing with slight memory savings. +/// Use ZIP compression for slow processing with large memory savings. +#[derive(Debug, Clone, Copy, PartialEq)] +pub enum Compression { + + /// Store uncompressed values. + /// Produces large files that can be read and written very quickly. + /// Consider using RLE instead, as it provides some compression with almost equivalent speed. + Uncompressed, + + /// Produces slightly smaller files + /// that can still be read and written rather quickly. + /// The compressed file size is usually between 60 and 75 percent of the uncompressed size. + /// Works best for images with large flat areas, such as masks and abstract graphics. + /// This compression method is lossless. + RLE, + + /// Uses ZIP compression to compress each line. Slowly produces small images + /// which can be read with moderate speed. This compression method is lossless. + /// Might be slightly faster but larger than `ZIP16´. + ZIP1, // TODO ZIP { individual_lines: bool, compression_level: Option<u8> } // TODO specify zip compression level? + + /// Uses ZIP compression to compress blocks of 16 lines. Slowly produces small images + /// which can be read with moderate speed. This compression method is lossless. + /// Might be slightly slower but smaller than `ZIP1´. + ZIP16, // TODO collapse with ZIP1 + + /// PIZ compression works well for noisy and natural images. Works better with larger tiles. + /// Only supported for flat images, but not for deep data. + /// This compression method is lossless. + // A wavelet transform is applied to the pixel data, and the result is Huffman- + // encoded. This scheme tends to provide the best compression ratio for the types of + // images that are typically processed at Industrial Light & Magic. Files are + // compressed and decompressed at roughly the same speed. For photographic + // images with film grain, the files are reduced to between 35 and 55 percent of their + // uncompressed size. + // PIZ compression works well for scan-line based files, and also for tiled files with + // large tiles, but small tiles do not shrink much. (PIZ-compressed data start with a + // relatively long header; if the input to the compressor is short, adding the header + // tends to offset any size reduction of the input.) + PIZ, + + /// Like `ZIP1`, but reduces precision of `f32` images to `f24`. + /// Therefore, this is lossless compression for `f16` and `u32` data, lossy compression for `f32` data. + /// This compression method works well for depth + /// buffers and similar images, where the possible range of values is very large, but + /// where full 32-bit floating-point accuracy is not necessary. Rounding improves + /// compression significantly by eliminating the pixels' 8 least significant bits, which + /// tend to be very noisy, and therefore difficult to compress. + /// This produces really small image files. Only supported for flat images, not for deep data. + // After reducing 32-bit floating-point data to 24 bits by rounding (while leaving 16-bit + // floating-point data unchanged), differences between horizontally adjacent pixels + // are compressed with zlib, similar to ZIP. PXR24 compression preserves image + // channels of type HALF and UINT exactly, but the relative error of FLOAT data + // increases to about ???. + PXR24, // TODO specify zip compression level? + + /// This is a lossy compression method for f16 images. + /// It's the predecessor of the `B44A` compression, + /// which has improved compression rates for uniformly colored areas. + /// You should probably use `B44A` instead of the plain `B44`. + /// + /// Only supported for flat images, not for deep data. + // lossy 4-by-4 pixel block compression, + // flat fields are compressed more + // Channels of type HALF are split into blocks of four by four pixels or 32 bytes. Each + // block is then packed into 14 bytes, reducing the data to 44 percent of their + // uncompressed size. When B44 compression is applied to RGB images in + // combination with luminance/chroma encoding (see below), the size of the + // compressed pixels is about 22 percent of the size of the original RGB data. + // Channels of type UINT or FLOAT are not compressed. + // Decoding is fast enough to allow real-time playback of B44-compressed OpenEXR + // image sequences on commodity hardware. + // The size of a B44-compressed file depends on the number of pixels in the image, + // but not on the data in the pixels. All images with the same resolution and the same + // set of channels have the same size. This can be advantageous for systems that + // support real-time playback of image sequences; the predictable file size makes it + // easier to allocate space on storage media efficiently. + // B44 compression is only supported for flat images. + B44, // TODO B44 { optimize_uniform_areas: bool } + + /// This is a lossy compression method for f16 images. + /// All f32 and u32 channels will be stored without compression. + /// All the f16 pixels are divided into 4x4 blocks. + /// Each block is then compressed as a whole. + /// + /// The 32 bytes of a block will require only ~14 bytes after compression, + /// independent of the actual pixel contents. With chroma subsampling, + /// a block will be compressed to ~7 bytes. + /// Uniformly colored blocks will be compressed to ~3 bytes. + /// + /// The 512 bytes of an f32 block will not be compressed at all. + /// + /// Should be fast enough for realtime playback. + /// Only supported for flat images, not for deep data. + B44A, // TODO collapse with B44 + + /// __This lossy compression is not yet supported by this implementation.__ + // lossy DCT based compression, in blocks + // of 32 scanlines. More efficient for partial buffer access. + DWAA(Option<f32>), // TODO does this have a default value? make this non optional? default Compression Level setting is 45.0 + + /// __This lossy compression is not yet supported by this implementation.__ + // lossy DCT based compression, in blocks + // of 256 scanlines. More efficient space + // wise and faster to decode full frames + // than DWAA_COMPRESSION. + DWAB(Option<f32>), // TODO collapse with B44. default Compression Level setting is 45.0 +} + +impl std::fmt::Display for Compression { + fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + write!(formatter, "{} compression", match self { + Compression::Uncompressed => "no", + Compression::RLE => "rle", + Compression::ZIP1 => "zip line", + Compression::ZIP16 => "zip block", + Compression::B44 => "b44", + Compression::B44A => "b44a", + Compression::DWAA(_) => "dwaa", + Compression::DWAB(_) => "dwab", + Compression::PIZ => "piz", + Compression::PXR24 => "pxr24", + }) + } +} + + + +impl Compression { + + /// Compress the image section of bytes. + pub fn compress_image_section(self, header: &Header, uncompressed_native_endian: ByteVec, pixel_section: IntegerBounds) -> Result<ByteVec> { + let max_tile_size = header.max_block_pixel_size(); + + assert!(pixel_section.validate(Some(max_tile_size)).is_ok(), "decompress tile coordinate bug"); + if header.deep { assert!(self.supports_deep_data()) } + + use self::Compression::*; + let compressed_little_endian = match self { + Uncompressed => { + return Ok(convert_current_to_little_endian( + uncompressed_native_endian, &header.channels, pixel_section + )) + }, + + // we need to clone here, because we might have to fallback to the uncompressed data later (when compressed data is larger than raw data) + ZIP16 => zip::compress_bytes(&header.channels, uncompressed_native_endian.clone(), pixel_section), + ZIP1 => zip::compress_bytes(&header.channels, uncompressed_native_endian.clone(), pixel_section), + RLE => rle::compress_bytes(&header.channels, uncompressed_native_endian.clone(), pixel_section), + PIZ => piz::compress(&header.channels, uncompressed_native_endian.clone(), pixel_section), + PXR24 => pxr24::compress(&header.channels, uncompressed_native_endian.clone(), pixel_section), + B44 => b44::compress(&header.channels, uncompressed_native_endian.clone(), pixel_section, false), + B44A => b44::compress(&header.channels, uncompressed_native_endian.clone(), pixel_section, true), + _ => return Err(Error::unsupported(format!("yet unimplemented compression method: {}", self))) + }; + + let compressed_little_endian = compressed_little_endian.map_err(|_| + Error::invalid(format!("pixels cannot be compressed ({})", self)) + )?; + + if self == Uncompressed || compressed_little_endian.len() < uncompressed_native_endian.len() { + // only write compressed if it actually is smaller than raw + Ok(compressed_little_endian) + } + else { + // if we do not use compression, manually convert uncompressed data + Ok(convert_current_to_little_endian(uncompressed_native_endian, &header.channels, pixel_section)) + } + } + + /// Decompress the image section of bytes. + pub fn decompress_image_section(self, header: &Header, compressed: ByteVec, pixel_section: IntegerBounds, pedantic: bool) -> Result<ByteVec> { + let max_tile_size = header.max_block_pixel_size(); + + assert!(pixel_section.validate(Some(max_tile_size)).is_ok(), "decompress tile coordinate bug"); + if header.deep { assert!(self.supports_deep_data()) } + + let expected_byte_size = pixel_section.size.area() * header.channels.bytes_per_pixel; // FIXME this needs to account for subsampling anywhere + + // note: always true where self == Uncompressed + if compressed.len() == expected_byte_size { + // the compressed data was larger than the raw data, so the small raw data has been written + Ok(convert_little_endian_to_current(compressed, &header.channels, pixel_section)) + } + else { + use self::Compression::*; + let bytes = match self { + Uncompressed => Ok(convert_little_endian_to_current(compressed, &header.channels, pixel_section)), + ZIP16 => zip::decompress_bytes(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + ZIP1 => zip::decompress_bytes(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + RLE => rle::decompress_bytes(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + PIZ => piz::decompress(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + PXR24 => pxr24::decompress(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + B44 | B44A => b44::decompress(&header.channels, compressed, pixel_section, expected_byte_size, pedantic), + _ => return Err(Error::unsupported(format!("yet unimplemented compression method: {}", self))) + }; + + // map all errors to compression errors + let bytes = bytes + .map_err(|decompression_error| match decompression_error { + Error::NotSupported(message) => + Error::unsupported(format!("yet unimplemented compression special case ({})", message)), + + error => Error::invalid(format!( + "compressed {:?} data ({})", + self, error.to_string() + )), + })?; + + if bytes.len() != expected_byte_size { + Err(Error::invalid("decompressed data")) + } + + else { Ok(bytes) } + } + } + + /// For scan line images and deep scan line images, one or more scan lines may be + /// stored together as a scan line block. The number of scan lines per block + /// depends on how the pixel data are compressed. + pub fn scan_lines_per_block(self) -> usize { + use self::Compression::*; + match self { + Uncompressed | RLE | ZIP1 => 1, + ZIP16 | PXR24 => 16, + PIZ | B44 | B44A | DWAA(_) => 32, + DWAB(_) => 256, + } + } + + /// Deep data can only be compressed using RLE or ZIP compression. + pub fn supports_deep_data(self) -> bool { + use self::Compression::*; + match self { + Uncompressed | RLE | ZIP1 => true, + _ => false, + } + } + + /// Most compression methods will reconstruct the exact pixel bytes, + /// but some might throw away unimportant data for specific types of samples. + pub fn is_lossless_for(self, sample_type: SampleType) -> bool { + use self::Compression::*; + match self { + PXR24 => sample_type != SampleType::F32, // pxr reduces f32 to f24 + B44 | B44A => sample_type != SampleType::F16, // b44 only compresses f16 values, others are left uncompressed + Uncompressed | RLE | ZIP1 | ZIP16 | PIZ => true, + DWAB(_) | DWAA(_) => false, + } + } + + /// Most compression methods will reconstruct the exact pixel bytes, + /// but some might throw away unimportant data in some cases. + pub fn may_loose_data(self) -> bool { + use self::Compression::*; + match self { + Uncompressed | RLE | ZIP1 | ZIP16 | PIZ => false, + PXR24 | B44 | B44A | DWAB(_) | DWAA(_) => true, + } + } + + /// Most compression methods will reconstruct the exact pixel bytes, + /// but some might replace NaN with zeroes. + pub fn supports_nan(self) -> bool { + use self::Compression::*; + match self { + B44 | B44A | DWAB(_) | DWAA(_) => false, // TODO dwa might support it? + _ => true + } + } + +} + +// see https://github.com/AcademySoftwareFoundation/openexr/blob/6a9f8af6e89547bcd370ae3cec2b12849eee0b54/OpenEXR/IlmImf/ImfMisc.cpp#L1456-L1541 + +#[allow(unused)] // allows the extra parameters to be unused +fn convert_current_to_little_endian(mut bytes: ByteVec, channels: &ChannelList, rectangle: IntegerBounds) -> ByteVec { + #[cfg(target = "big_endian")] + reverse_block_endianness(&mut byte_vec, channels, rectangle); + + bytes +} + +#[allow(unused)] // allows the extra parameters to be unused +fn convert_little_endian_to_current(mut bytes: ByteVec, channels: &ChannelList, rectangle: IntegerBounds) -> ByteVec { + #[cfg(target = "big_endian")] + reverse_block_endianness(&mut bytes, channels, rectangle); + + bytes +} + +#[allow(unused)] // unused when on little endian system +fn reverse_block_endianness(bytes: &mut [u8], channels: &ChannelList, rectangle: IntegerBounds){ + let mut remaining_bytes: &mut [u8] = bytes; + + for y in rectangle.position.y() .. rectangle.end().y() { + for channel in &channels.list { + let line_is_subsampled = mod_p(y, usize_to_i32(channel.sampling.y())) != 0; + if line_is_subsampled { continue; } + + let sample_count = rectangle.size.width() / channel.sampling.x(); + + match channel.sample_type { + SampleType::F16 => remaining_bytes = chomp_convert_n::<f16>(reverse_2_bytes, remaining_bytes, sample_count), + SampleType::F32 => remaining_bytes = chomp_convert_n::<f32>(reverse_4_bytes, remaining_bytes, sample_count), + SampleType::U32 => remaining_bytes = chomp_convert_n::<u32>(reverse_4_bytes, remaining_bytes, sample_count), + } + } + } + + #[inline] + fn chomp_convert_n<T>(convert_single_value: fn(&mut[u8]), mut bytes: &mut [u8], count: usize) -> &mut [u8] { + let type_size = size_of::<T>(); + let (line_bytes, rest) = bytes.split_at_mut(count * type_size); + let value_byte_chunks = line_bytes.chunks_exact_mut(type_size); + + for value_bytes in value_byte_chunks { + convert_single_value(value_bytes); + } + + rest + } + + debug_assert!(remaining_bytes.is_empty(), "not all bytes were converted to little endian"); +} + +#[inline] +fn reverse_2_bytes(bytes: &mut [u8]){ + // this code seems like it could be optimized easily by the compiler + let two_bytes: [u8; 2] = bytes.try_into().expect("invalid byte count"); + bytes.copy_from_slice(&[two_bytes[1], two_bytes[0]]); +} + +#[inline] +fn reverse_4_bytes(bytes: &mut [u8]){ + let four_bytes: [u8; 4] = bytes.try_into().expect("invalid byte count"); + bytes.copy_from_slice(&[four_bytes[3], four_bytes[2], four_bytes[1], four_bytes[0]]); +} + +#[inline] +fn div_p (x: i32, y: i32) -> i32 { + if x >= 0 { + if y >= 0 { x / y } + else { -(x / -y) } + } + else { + if y >= 0 { -((y-1-x) / y) } + else { (-y-1-x) / -y } + } +} + +#[inline] +fn mod_p(x: i32, y: i32) -> i32 { + x - y * div_p(x, y) +} + +/// A collection of functions used to prepare data for compression. +mod optimize_bytes { + + /// Integrate over all differences to the previous value in order to reconstruct sample values. + pub fn differences_to_samples(buffer: &mut [u8]) { + // The naive implementation is very simple: + // + // for index in 1..buffer.len() { + // buffer[index] = (buffer[index - 1] as i32 + buffer[index] as i32 - 128) as u8; + // } + // + // But we process elements in pairs to take advantage of instruction-level parallelism. + // When computations within a pair do not depend on each other, they can be processed in parallel. + // Since this function is responsible for a very large chunk of execution time, + // this tweak alone improves decoding performance of RLE images by 20%. + if let Some(first) = buffer.get(0) { + let mut previous = *first as i16; + for chunk in &mut buffer[1..].chunks_exact_mut(2) { + // no bounds checks here due to indices and chunk size being constant + let diff0 = chunk[0] as i16; + let diff1 = chunk[1] as i16; + // these two computations do not depend on each other, unlike in the naive version, + // so they can be executed by the CPU in parallel via instruction-level parallelism + let sample0 = (previous + diff0 - 128) as u8; + let sample1 = (previous + diff0 + diff1 - 128 * 2) as u8; + chunk[0] = sample0; + chunk[1] = sample1; + previous = sample1 as i16; + } + // handle the remaining element at the end not processed by the loop over pairs, if present + for elem in &mut buffer[1..].chunks_exact_mut(2).into_remainder().iter_mut() { + let sample = (previous + *elem as i16 - 128) as u8; + *elem = sample; + previous = sample as i16; + } + } + } + + /// Derive over all values in order to produce differences to the previous value. + pub fn samples_to_differences(buffer: &mut [u8]){ + // naive version: + // for index in (1..buffer.len()).rev() { + // buffer[index] = (buffer[index] as i32 - buffer[index - 1] as i32 + 128) as u8; + // } + // + // But we process elements in batches to take advantage of autovectorization. + // If the target platform has no vector instructions (e.g. 32-bit ARM without `-C target-cpu=native`) + // this will instead take advantage of instruction-level parallelism. + if let Some(first) = buffer.get(0) { + let mut previous = *first as i16; + // Chunk size is 16 because we process bytes (8 bits), + // and 8*16 = 128 bits is the size of a typical SIMD register. + // Even WASM has 128-bit SIMD registers. + for chunk in &mut buffer[1..].chunks_exact_mut(16) { + // no bounds checks here due to indices and chunk size being constant + let sample0 = chunk[0] as i16; + let sample1 = chunk[1] as i16; + let sample2 = chunk[2] as i16; + let sample3 = chunk[3] as i16; + let sample4 = chunk[4] as i16; + let sample5 = chunk[5] as i16; + let sample6 = chunk[6] as i16; + let sample7 = chunk[7] as i16; + let sample8 = chunk[8] as i16; + let sample9 = chunk[9] as i16; + let sample10 = chunk[10] as i16; + let sample11 = chunk[11] as i16; + let sample12 = chunk[12] as i16; + let sample13 = chunk[13] as i16; + let sample14 = chunk[14] as i16; + let sample15 = chunk[15] as i16; + // Unlike in decoding, computations in here are truly independent from each other, + // which enables the compiler to vectorize this loop. + // Even if the target platform has no vector instructions, + // so using more parallelism doesn't imply doing more work, + // and we're not really limited in how wide we can go. + chunk[0] = (sample0 - previous + 128) as u8; + chunk[1] = (sample1 - sample0 + 128) as u8; + chunk[2] = (sample2 - sample1 + 128) as u8; + chunk[3] = (sample3 - sample2 + 128) as u8; + chunk[4] = (sample4 - sample3 + 128) as u8; + chunk[5] = (sample5 - sample4 + 128) as u8; + chunk[6] = (sample6 - sample5 + 128) as u8; + chunk[7] = (sample7 - sample6 + 128) as u8; + chunk[8] = (sample8 - sample7 + 128) as u8; + chunk[9] = (sample9 - sample8 + 128) as u8; + chunk[10] = (sample10 - sample9 + 128) as u8; + chunk[11] = (sample11 - sample10 + 128) as u8; + chunk[12] = (sample12 - sample11 + 128) as u8; + chunk[13] = (sample13 - sample12 + 128) as u8; + chunk[14] = (sample14 - sample13 + 128) as u8; + chunk[15] = (sample15 - sample14 + 128) as u8; + previous = sample15; + } + // Handle the remaining element at the end not processed by the loop over batches, if present + // This is what the iterator-based version of this function would look like without vectorization + for elem in &mut buffer[1..].chunks_exact_mut(16).into_remainder().iter_mut() { + let diff = (*elem as i16 - previous + 128) as u8; + previous = *elem as i16; + *elem = diff; + } + } + } + + use std::cell::Cell; + thread_local! { + // A buffer for reusing between invocations of interleaving and deinterleaving. + // Allocating memory is cheap, but zeroing or otherwise initializing it is not. + // Doing it hundreds of times (once per block) would be expensive. + // This optimization brings down the time spent in interleaving from 15% to 5%. + static SCRATCH_SPACE: Cell<Vec<u8>> = Cell::new(Vec::new()); + } + + fn with_reused_buffer<F>(length: usize, mut func: F) where F: FnMut(&mut [u8]) { + SCRATCH_SPACE.with(|scratch_space| { + // reuse a buffer if we've already initialized one + let mut buffer = scratch_space.take(); + if buffer.len() < length { + // Efficiently create a zeroed Vec by requesting zeroed memory from the OS. + // This is slightly faster than a `memcpy()` plus `memset()` that would happen otherwise, + // but is not a big deal either way since it's not a hot codepath. + buffer = vec![0u8; length]; + } + + // call the function + func(&mut buffer[..length]); + + // save the internal buffer for reuse + scratch_space.set(buffer); + }); + } + + /// Interleave the bytes such that the second half of the array is every other byte. + pub fn interleave_byte_blocks(separated: &mut [u8]) { + with_reused_buffer(separated.len(), |interleaved| { + + // Split the two halves that we are going to interleave. + let (first_half, second_half) = separated.split_at((separated.len() + 1) / 2); + // The first half can be 1 byte longer than the second if the length of the input is odd, + // but the loop below only processes numbers in pairs. + // To handle it, preserve the last element of the first slice, to be handled after the loop. + let first_half_last = first_half.last(); + // Truncate the first half to match the lenght of the second one; more optimizer-friendly + let first_half_iter = &first_half[..second_half.len()]; + + // Main loop that performs the interleaving + for ((first, second), interleaved) in first_half_iter.iter().zip(second_half.iter()) + .zip(interleaved.chunks_exact_mut(2)) { + // The length of each chunk is known to be 2 at compile time, + // and each index is also a constant. + // This allows the compiler to remove the bounds checks. + interleaved[0] = *first; + interleaved[1] = *second; + } + + // If the length of the slice was odd, restore the last element of the first half that we saved + if interleaved.len() % 2 == 1 { + if let Some(value) = first_half_last { + // we can unwrap() here because we just checked that the lenght is non-zero: + // `% 2 == 1` will fail for zero + *interleaved.last_mut().unwrap() = *value; + } + } + + // write out the results + separated.copy_from_slice(&interleaved); + }); + } + +/// Separate the bytes such that the second half contains every other byte. +/// This performs deinterleaving - the inverse of interleaving. +pub fn separate_bytes_fragments(source: &mut [u8]) { + with_reused_buffer(source.len(), |separated| { + + // Split the two halves that we are going to interleave. + let (first_half, second_half) = separated.split_at_mut((source.len() + 1) / 2); + // The first half can be 1 byte longer than the second if the length of the input is odd, + // but the loop below only processes numbers in pairs. + // To handle it, preserve the last element of the input, to be handled after the loop. + let last = source.last(); + let first_half_iter = &mut first_half[..second_half.len()]; + + // Main loop that performs the deinterleaving + for ((first, second), interleaved) in first_half_iter.iter_mut().zip(second_half.iter_mut()) + .zip(source.chunks_exact(2)) { + // The length of each chunk is known to be 2 at compile time, + // and each index is also a constant. + // This allows the compiler to remove the bounds checks. + *first = interleaved[0]; + *second = interleaved[1]; + } + + // If the length of the slice was odd, restore the last element of the input that we saved + if source.len() % 2 == 1 { + if let Some(value) = last { + // we can unwrap() here because we just checked that the lenght is non-zero: + // `% 2 == 1` will fail for zero + *first_half.last_mut().unwrap() = *value; + } + } + + // write out the results + source.copy_from_slice(&separated); + }); +} + + + #[cfg(test)] + pub mod test { + + #[test] + fn roundtrip_interleave(){ + let source = vec![ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]; + let mut modified = source.clone(); + + super::separate_bytes_fragments(&mut modified); + super::interleave_byte_blocks(&mut modified); + + assert_eq!(source, modified); + } + + #[test] + fn roundtrip_derive(){ + let source = vec![ 0, 1, 2, 7, 4, 5, 6, 7, 13, 9, 10 ]; + let mut modified = source.clone(); + + super::samples_to_differences(&mut modified); + super::differences_to_samples(&mut modified); + + assert_eq!(source, modified); + } + + } +} + + +#[cfg(test)] +pub mod test { + use super::*; + use crate::meta::attribute::ChannelDescription; + use crate::block::samples::IntoNativeSample; + + #[test] + fn roundtrip_endianness_mixed_channels(){ + let a32 = ChannelDescription::new("A", SampleType::F32, true); + let y16 = ChannelDescription::new("Y", SampleType::F16, true); + let channels = ChannelList::new(smallvec![ a32, y16 ]); + + let data = vec![ + 23582740683_f32.to_ne_bytes().as_slice(), + 35827420683_f32.to_ne_bytes().as_slice(), + 27406832358_f32.to_f16().to_ne_bytes().as_slice(), + 74062358283_f32.to_f16().to_ne_bytes().as_slice(), + + 52582740683_f32.to_ne_bytes().as_slice(), + 45827420683_f32.to_ne_bytes().as_slice(), + 15406832358_f32.to_f16().to_ne_bytes().as_slice(), + 65062358283_f32.to_f16().to_ne_bytes().as_slice(), + ].into_iter().flatten().map(|x| *x).collect(); + + roundtrip_convert_endianness( + data, &channels, + IntegerBounds::from_dimensions((2, 2)) + ); + } + + fn roundtrip_convert_endianness( + current_endian: ByteVec, channels: &ChannelList, rectangle: IntegerBounds + ){ + let little_endian = convert_current_to_little_endian( + current_endian.clone(), channels, rectangle + ); + + let current_endian_decoded = convert_little_endian_to_current( + little_endian.clone(), channels, rectangle + ); + + assert_eq!(current_endian, current_endian_decoded, "endianness conversion failed"); + } +}
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