Hex to Binary Converter

Hexadecimal notation compresses binary data by a factor of 4: each hex digit maps to exactly 4 binary bits. Misreading a single nibble - confusing B (1011) with D (1101) - flips two bits simultaneously, which in register-level firmware or network mask configuration causes silent, hard-to-trace failures. This converter performs a deterministic lookup per digit, preserving leading zeros so the output width always equals 4n bits for n hex characters. It handles arbitrary-length input, not just 8-, 16-, or 32-bit words.

The tool assumes unsigned interpretation. It does not infer signedness or endianness - those are context-dependent decisions the engineer must make. For IEEE 754 floats or two's complement integers, convert here first, then apply the sign/exponent logic appropriate to your architecture.

The conversion is a direct substitution cipher. Each hexadecimal digit is replaced by its fixed 4-bit binary equivalent from a lookup table T.

Where H is the input hex string of length n, H_i is the i-th character, T is the nibble lookup table mapping 0 - F → 0000 - 1111, and ⋅ denotes string concatenation. The output length is always 4n bits. No arithmetic is performed - the mapping is purely lexical.

For the reverse verification: bin2hex(B) groups the binary string into 4-bit chunks from the right, padding with leading zeros if len(B) mod 4 ≠ 0, then applies the inverse table T⁻¹.