46 lines
1.8 KiB
Rust
46 lines
1.8 KiB
Rust
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use deku::ctx::BitSize;
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use deku::prelude::*;
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use deku::reader::ReaderRet;
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use deku::{reader::Reader, DekuError};
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pub mod blocks;
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pub mod groups;
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pub mod prelude;
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pub use blocks::Data;
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/// # Read the size of a FSV block / field
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/// Documentation: SSV Documentation, page 29
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fn size_read<R: std::io::Read + std::io::Seek>(reader: &mut Reader<R>) -> Result<u64, DekuError> {
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let size_bytes = u8::from_reader_with_ctx(reader, BitSize(8))?;
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let size: u64 = if size_bytes & 0b1000_0000 == 0 {
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// If the Most Significant Bit is 0, the size is encoded on 7 bits
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size_bytes.into()
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} else {
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// Else, the 7 following bits indicate the number of bytes of the block containing the size
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let size_block_len: usize = (size_bytes & 0b0111_1111).into();
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if size_block_len > 4 {
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return Err(DekuError::Parse(format!("Unexpected size block length: {}", size_block_len).into()));
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};
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// The block containing the size is encoded on 1 to 4 bytes
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let buffer: &mut [u8; 4] = &mut [0; 4];
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let write_offset = 4 - size_block_len;
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match reader.read_bytes(size_block_len, &mut buffer[write_offset..])? {
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ReaderRet::Bits(_bit_vec) => return Err(DekuError::Parse("Unexpected result reading size bytes: got bits".into())),
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ReaderRet::Bytes => u32::from_be_bytes(*buffer).into(),
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}
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};
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Ok(size)
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}
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/// # Map bytes to a lossy string
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/// This function is used to map bytes to a string, ignoring invalid UTF-8 characters
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/// Example: [0x41, 0x42] -> "AB"
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/// Example: [48, 49, 50, 51] -> "0123"
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fn map_bytes_to_lossy_string(data: &[u8]) -> Result<String, DekuError> {
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// let data = data.to_vec();
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let version: String = String::from_utf8_lossy(data).to_string();
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Ok(version)
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}
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