From 6c94102afc70ce28eee3d17aad997a056aaf9195 Mon Sep 17 00:00:00 2001 From: Silas Bartha Date: Fri, 11 Oct 2024 19:01:52 -0400 Subject: gltf, wav, and binary codecs --- src/binary/reverse_appendix.rs | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 src/binary/reverse_appendix.rs (limited to 'src/binary/reverse_appendix.rs') diff --git a/src/binary/reverse_appendix.rs b/src/binary/reverse_appendix.rs new file mode 100644 index 0000000..d131526 --- /dev/null +++ b/src/binary/reverse_appendix.rs @@ -0,0 +1,35 @@ +use crate::{Codec, Error}; + +/// Reverses payload binary data and writes it ass-first past the end of the original data. A +/// length marker is also prepended to the payload *before reversing* so the decoder knows how long +/// the payload is. +pub struct BinaryReverseAppendixCodec; + +impl Codec for BinaryReverseAppendixCodec { + fn encode(&self, carrier: &[u8], payload: &[u8]) -> Result, crate::Error> { + let mut encoded = Vec::::new(); + encoded.extend(carrier.iter()); + let payload_len = (payload.len() as u64 + 8).to_le_bytes(); + encoded.extend(payload_len.iter().chain(payload.iter()).rev()); + Ok(encoded) + } + + fn decode(&self, encoded: &[u8]) -> Result<(Vec, Vec), crate::Error> { + if encoded.len() < 8 { + return Err(Error::DataNotEncoded); + } + + let encoded_len = encoded.len(); + let payload_len = u64::from_le_bytes(encoded.iter().rev().take(8).cloned().collect::>().try_into().unwrap()) as usize; + if encoded_len < payload_len + 8 || payload_len < 8 { + return Err(Error::DataNotEncoded); + } + + let carrier_len = encoded_len - payload_len; + + let carrier = encoded[..carrier_len].to_vec(); + let payload = encoded.iter().rev().skip(8).take(payload_len - 8).cloned().collect::>(); + + Ok((carrier, payload)) + } +} -- cgit v1.2.3