Add FNV-1a hash algorithm implementation with 32-bit and 64-bit variants

Author: dinilH

hashes/fnv1a.py

@@ -0,0 +1,135 @@
+"""
+FNV-1a (Fowler-Noll-Vo) is a non-cryptographic hash function created by
+Glenn Fowler, Landon Curt Noll, and Kiem-Phong Vo.
+
+The FNV-1a variant provides better avalanche characteristics (bit changes
+distribute more uniformly) compared to the original FNV-1.
+
+Key properties:
+- Fast computation
+- Good distribution
+- Non-cryptographic (not suitable for security purposes)
+- Widely used in hash tables and checksums
+
+Algorithm:
+    hash = FNV_offset_basis
+    for each byte in data:
+        hash = hash XOR byte
+        hash = hash * FNV_prime
+
+FNV-1a 32-bit:
+    FNV_offset_basis = 2166136261 (0x811c9dc5)
+    FNV_prime = 16777619 (0x01000193)
+
+FNV-1a 64-bit:
+    FNV_offset_basis = 14695981039346656037 (0xcbf29ce484222325)
+    FNV_prime = 1099511628211 (0x100000001b3)
+
+Source: http://www.isthe.com/chongo/tech/comp/fnv/
+"""
+
+
+def fnv1a_32(data: str) -> int:
+    """
+    Implementation of 32-bit FNV-1a hash algorithm.
+
+    Args:
+        data: Input string to hash
+
+    Returns:
+        32-bit hash value as integer
+
+    Examples:
+        >>> fnv1a_32('Hello')
+        4116459851
+        >>> fnv1a_32('World')
+        3714116915
+        >>> fnv1a_32('Algorithms')
+        3235099003
+        >>> fnv1a_32('')
+        2166136261
+        >>> fnv1a_32('The quick brown fox jumps over the lazy dog')
+        76545936
+        >>> fnv1a_32('a')
+        3826002220
+        >>> fnv1a_32('ab')
+        1294271946
+        >>> fnv1a_32('abc')
+        440920331
+
+    Test with same input produces same output:
+        >>> fnv1a_32('test') == fnv1a_32('test')
+        True
+
+    Test different inputs produce different outputs:
+        >>> fnv1a_32('test') != fnv1a_32('Test')
+        True
+    """
+    # FNV-1a 32-bit parameters
+    fnv_offset_basis = 0x811C9DC5  # 2166136261
+    fnv_prime = 0x01000193  # 16777619
+
+    hash_value = fnv_offset_basis
+
+    for byte in data.encode("utf-8"):
+        hash_value ^= byte  # XOR with byte
+        hash_value *= fnv_prime  # Multiply by FNV prime
+        hash_value &= 0xFFFFFFFF  # Keep it 32-bit
+
+    return hash_value
+
+
+def fnv1a_64(data: str) -> int:
+    """
+    Implementation of 64-bit FNV-1a hash algorithm.
+
+    Args:
+        data: Input string to hash
+
+    Returns:
+        64-bit hash value as integer
+
+    Examples:
+        >>> fnv1a_64('Hello')
+        7201466553693376363
+        >>> fnv1a_64('World')
+        1088154518318865747
+        >>> fnv1a_64('Algorithms')
+        2924617064648692923
+        >>> fnv1a_64('')
+        14695981039346656037
+        >>> fnv1a_64('The quick brown fox jumps over the lazy dog')
+        17580284887202820368
+        >>> fnv1a_64('a')
+        12638187200555641996
+        >>> fnv1a_64('ab')
+        620445648566982762
+        >>> fnv1a_64('abc')
+        16654208175385433931
+
+    Test with same input produces same output:
+        >>> fnv1a_64('test') == fnv1a_64('test')
+        True
+
+    Test different inputs produce different outputs:
+        >>> fnv1a_64('test') != fnv1a_64('Test')
+        True
+    """
+    # FNV-1a 64-bit parameters
+    fnv_offset_basis = 0xCBF29CE484222325  # 14695981039346656037
+    fnv_prime = 0x100000001B3  # 1099511628211
+
+    hash_value = fnv_offset_basis
+
+    for byte in data.encode("utf-8"):
+        hash_value ^= byte  # XOR with byte
+        hash_value *= fnv_prime  # Multiply by FNV prime
+        hash_value &= 0xFFFFFFFFFFFFFFFF  # Keep it 64-bit
+
+    return hash_value
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()