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fnv1a

FNV-1a hash implementation for firmware key hashing.

fnv1a_hash(string) cached #

Compute FNV-1a 32-bit hash of a string.

This matches the firmware's hash implementation used for parameter and telemetry keys. Results are cached to avoid recomputing hashes for previously seen strings.

Parameters:

Name Type Description Default
string str

The string to hash.

 required

Returns:

Type Description
int

32-bit FNV-1a hash value.
Example

hex(fnv1a_hash("parameter")) '0x100b'

Source code in cogip/utils/fnv1a.py 
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@cache
def fnv1a_hash(string: str) -> int:
    """
    Compute FNV-1a 32-bit hash of a string.

    This matches the firmware's hash implementation used for parameter
    and telemetry keys. Results are cached to avoid recomputing hashes
    for previously seen strings.

    Args:
        string: The string to hash.

    Returns:
        32-bit FNV-1a hash value.

    Example:
        >>> hex(fnv1a_hash("parameter"))
        '0x100b'
    """
    FNV_OFFSET_BASIS = 0x811C9DC5
    FNV_PRIME = 0x01000193

    hash_value = FNV_OFFSET_BASIS

    for byte in string.encode("utf-8"):
        hash_value ^= byte
        hash_value = (hash_value * FNV_PRIME) & 0xFFFFFFFF

    return hash_value