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import sys
import unittest
from test.support import import_helper
_testcapi = import_helper.import_module('_testcapi')
SIZEOF_VOID_P = _testcapi.SIZEOF_VOID_P
SIZEOF_PY_HASH_T = SIZEOF_VOID_P
class CAPITest(unittest.TestCase):
def test_hash_getfuncdef(self):
# Test PyHash_GetFuncDef()
hash_getfuncdef = _testcapi.hash_getfuncdef
func_def = hash_getfuncdef()
match func_def.name:
case "fnv":
self.assertEqual(func_def.hash_bits, 8 * SIZEOF_PY_HASH_T)
self.assertEqual(func_def.seed_bits, 16 * SIZEOF_PY_HASH_T)
case "siphash13":
self.assertEqual(func_def.hash_bits, 64)
self.assertEqual(func_def.seed_bits, 128)
case "siphash24":
self.assertEqual(func_def.hash_bits, 64)
self.assertEqual(func_def.seed_bits, 128)
case _:
self.fail(f"unknown function name: {func_def.name!r}")
# compare with sys.hash_info
hash_info = sys.hash_info
self.assertEqual(func_def.name, hash_info.algorithm)
self.assertEqual(func_def.hash_bits, hash_info.hash_bits)
self.assertEqual(func_def.seed_bits, hash_info.seed_bits)
def test_hash_pointer(self):
# Test Py_HashPointer()
hash_pointer = _testcapi.hash_pointer
UHASH_T_MASK = ((2 ** (8 * SIZEOF_PY_HASH_T)) - 1)
HASH_T_MAX = (2 ** (8 * SIZEOF_PY_HASH_T - 1) - 1)
def python_hash_pointer(x):
# Py_HashPointer() rotates the pointer bits by 4 bits to the right
x = (x >> 4) | ((x & 15) << (8 * SIZEOF_VOID_P - 4))
# Convert unsigned uintptr_t (Py_uhash_t) to signed Py_hash_t
if HASH_T_MAX < x:
x = (~x) + 1
x &= UHASH_T_MASK
x = (~x) + 1
return x
if SIZEOF_VOID_P == 8:
values = (
0xABCDEF1234567890,
0x1234567890ABCDEF,
0xFEE4ABEDD1CECA5E,
)
else:
values = (
0x12345678,
0x1234ABCD,
0xDEADCAFE,
)
for value in values:
expected = python_hash_pointer(value)
with self.subTest(value=value):
self.assertEqual(hash_pointer(value), expected,
f"hash_pointer({value:x}) = "
f"{hash_pointer(value):x} != {expected:x}")
# Py_HashPointer(NULL) returns 0
self.assertEqual(hash_pointer(0), 0)
# Py_HashPointer((void*)(uintptr_t)-1) doesn't return -1 but -2
VOID_P_MAX = -1 & (2 ** (8 * SIZEOF_VOID_P) - 1)
self.assertEqual(hash_pointer(VOID_P_MAX), -2)
if __name__ == "__main__":
unittest.main()
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