nim-stint/tests/test_mul.nim

27 lines
919 B
Nim

# Copyright (c) 2018 Status Research & Development GmbH
# Distributed under the MIT License (license terms are at http://opensource.org/licenses/MIT).
import ../src/mpint, unittest
suite "Testing multiplication implementation":
test "Multiplication with result fitting in low half":
let a = initMpUint(10000, uint32)
let b = initMpUint(10000, uint32)
check: cast[uint64](a*b) == 100_000_000'u64 # need 27-bits
test "Multiplication with result overflowing low half":
let a = initMpUint(1_000_000, uint32)
let b = initMpUint(1_000_000, uint32)
check: cast[uint64](a*b) == 1_000_000_000_000'u64 # need 40 bits
test "Full overflow is handled like native unsigned types":
let a = initMpUint(1_000_000_000, uint32)
let b = initMpUint(1_000_000_000, uint32)
let c = initMpUint(1_000, uint32)
check: cast[uint64](a*b*c) == 1_000_000_000_000_000_000_000'u64 # need 70-bits