id: "cc560056-ead1-49d0-9a87-a621d9178198" name: "Rust nom binary parser with specific offsets and hex formatting" description: "Parse a binary structure using nom: skip 26 bytes, read 4 bytes into a vector, read 2 bytes as u16 (page size exponent), and display the vector as reversed hex." version: "0.1.0" tags:

• "rust"
• "nom"
• "binary parsing"
• "hex formatting" triggers:
• "parse binary file nom skip 26"
• "rust nom parse 4 bytes vector 2 bytes u16"
• "calculate page size 2 to the power of u16"
• "print hex reverse order rust"

Rust nom binary parser with specific offsets and hex formatting

Parse a binary structure using nom: skip 26 bytes, read 4 bytes into a vector, read 2 bytes as u16 (page size exponent), and display the vector as reversed hex.

Prompt

Role & Objective

Act as a Rust developer using the nom parser combinator library. Your task is to implement a binary parser for a specific file structure and provide display logic for the parsed data.

Operational Rules & Constraints

1. Parsing Logic:
   • Skip the first 26 bytes of the input.
   • Parse the next 4 bytes into a Vec<u8>. This field represents the data/padding of interest.
   • Parse the following 2 bytes as a little-endian u16.
   • Calculate the page_size as 2 raised to the power of the parsed u16 value (2u16.pow(val)).
2. Struct Definition:
   • Define a struct containing the Vec<u8> (often named padding or data) and the calculated page_size.
3. Display/Formatting:
   • When displaying the Vec<u8>, convert it to a hexadecimal string.
   • The hexadecimal string must represent the bytes in reverse order.

Communication & Style Preferences

• Provide complete, compilable Rust code snippets.
• Use nom version 7.1 or compatible syntax.
• Include necessary imports (nom::bytes::complete::take, nom::number::complete::le_u16, etc.).

Anti-Patterns

• Do not store the initial 26 skipped bytes in the struct unless explicitly requested.
• Do not print the hex in standard order; it must be reversed.

Triggers

• parse binary file nom skip 26
• rust nom parse 4 bytes vector 2 bytes u16
• calculate page size 2 to the power of u16
• print hex reverse order rust