143 lines
4.1 KiB
Rust
143 lines
4.1 KiB
Rust
use crate::byte_stream::{ByteStream, bit_mask};
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use serde::Deserialize;
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use std::fmt::Write;
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use num_bigint::{BigUint, BigInt};
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#[derive(Debug, Deserialize, Clone)]
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#[serde(tag = "type")]
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pub enum FieldType {
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/// Unsigned Int
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UInt { bit_width: usize },
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/// Unsigned Int
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Int { bit_width: usize },
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/// Null Terminated String Field
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String { max_len: usize },
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/// Fixed Byte Length Field
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Bytes { max_len: usize },
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}
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#[derive(Debug, Deserialize, Clone)]
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pub struct Field {
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/// Field Name
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pub name: String,
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/// Field Type
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pub field_type: FieldType,
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}
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impl Field {
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fn format_int(byte_stream: &ByteStream, bit_ndx: usize, bit_width: usize) -> (String, usize) {
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let mut bytes = byte_stream.get_bytes(bit_ndx, bit_width).unwrap();
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if let Some(last_byte) = bytes.last_mut() {
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let last_bit = ((bit_width - 1) % 8) as u8;
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let sign_bit = (*last_byte >> last_bit) & 0x1 == 1;
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if sign_bit {
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// Sign extend
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*last_byte |= !bit_mask(last_bit + 1)
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}
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let big_int = BigInt::from_signed_bytes_be(&bytes);
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(big_int.to_string(), bit_width)
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}
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else {
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("".to_string(), bit_width)
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}
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}
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fn format_uint(byte_stream: &ByteStream, bit_ndx: usize, bit_width: usize) -> (String, usize) {
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let bytes = byte_stream.get_bytes(bit_ndx, bit_width).unwrap();
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let big_int = BigUint::from_bytes_be(&bytes);
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(big_int.to_string(), bit_width)
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}
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fn format_data(&self, byte_stream: &ByteStream, bit_ndx: usize) -> (String, usize) {
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match self.field_type {
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FieldType::UInt { bit_width } => Self::format_uint(byte_stream, bit_ndx, bit_width),
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FieldType::Int { bit_width } => Self::format_int(byte_stream, bit_ndx, bit_width),
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_ => ("".to_string(), 0),
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}
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}
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}
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#[derive(Debug, Deserialize, Clone)]
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pub struct Format {
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/// Format Name
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pub name: String,
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/// Elements of the format
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pub fields: Vec<Field>,
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}
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impl Format {
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pub fn format_data(&self, data: &[u8]) -> String {
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let mut s = String::new();
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let byte_stream = ByteStream::from(data);
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let mut bit_ndx: usize = 0;
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for field in &self.fields {
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let (data_str, bit_width) = field.format_data(&byte_stream, bit_ndx);
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bit_ndx += bit_width;
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writeln!(s, "{}: {}", field.name, data_str).unwrap();
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}
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s
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::formatter::format::{FieldType, Field};
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use crate::byte_stream::ByteStream;
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#[test]
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fn test_format_int_4_bits() {
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let field = Field {field_type: FieldType::Int {bit_width: 4,}, name: "test".to_string()};
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for i in 0i8..7i8 {
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let mut byte_vec = Vec::new();
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byte_vec.push(i as u8);
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byte_vec.push((-i) as u8);
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let byte_steam = ByteStream::from(byte_vec);
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let (pos_output, _) = field.format_data(&byte_steam, 0);
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let (neg_output, _) = field.format_data(&byte_steam, 8);
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assert_eq!(pos_output, i.to_string());
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assert_eq!(neg_output, (-i).to_string());
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}
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}
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#[test]
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fn test_format_int_5_bits() {
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let field = Field {field_type: FieldType::Int {bit_width: 5,}, name: "test".to_string()};
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let byte_steam = ByteStream::from(vec![0x1B]);
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let (output, _) = field.format_data(&byte_steam, 0);
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assert_eq!(output, "-5")
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}
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#[test]
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fn test_format_int_16_bits() {
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let field = Field {field_type: FieldType::Int {bit_width: 16,}, name: "test".to_string()};
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let byte_steam = ByteStream::from(vec![0xA5, 0xFC]);
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let (output, _) = field.format_data(&byte_steam, 0);
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assert_eq!(output, "-23044")
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}
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#[test]
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fn test_format_int_16_bits_not_aligned() {
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let field = Field {field_type: FieldType::Int {bit_width: 16,}, name: "test".to_string()};
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let byte_steam = ByteStream::from(vec![0x50, 0xCA, 0x0F]);
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let (output, _) = field.format_data(&byte_steam, 4);
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assert_eq!(output, "-23044")
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}
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}
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