nim-stint/tests/test_uint_mul.nim

# Stint
# Copyright 2018 Status Research & Development GmbH
# Licensed under either of
#
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
#
# at your option. This file may not be copied, modified, or distributed except according to those terms.

import ../stint, unittest, test_helpers

template chkMul(chk: untyped, a, b, c: string, bits: int) =
  chk (fromHex(StUint[bits], a) * fromHex(StUint[bits], b)) == fromHex(StUint[bits], c)

template testMul(chk, tst: untyped) =
  tst "operator `mul`":
    #[chkMul(chk, "0", "3", "0", 8)
    chkMul(chk, "1", "3", "3", 8)
    chkMul(chk, "64", "3", "2C", 8) # overflow

    chkMul(chk, "0", "3", "0", 16)
    chkMul(chk, "1", "3", "3", 16)
    chkMul(chk, "64", "3", "12C", 16)
    chkMul(chk, "1770", "46", "68A0", 16) # overflow

    chkMul(chk, "0", "3", "0", 32)
    chkMul(chk, "1", "3", "3", 32)
    chkMul(chk, "64", "3", "12C", 32)
    chkMul(chk, "1770", "46", "668A0", 32)
    chkMul(chk, "13880", "13880", "7D784000", 32) # overflow

    chkMul(chk, "0", "3", "0", 64)
    chkMul(chk, "1", "3", "3", 64)
    chkMul(chk, "64", "3", "12C", 64)
    chkMul(chk, "1770", "46", "668A0", 64)
    chkMul(chk, "13880", "13880", "17D784000", 64)
    chkMul(chk, "3B9ACA00", "E8D4A51000", "35C9ADC5DEA00000", 64) # overflow]#

    chkMul(chk, "0", "3", "0", 128)
    chkMul(chk, "1", "3", "3", 128)
    chkMul(chk, "64", "3", "12C", 128)
    chkMul(chk, "1770", "46", "668A0", 128)
    chkMul(chk, "13880", "13880", "17D784000", 128)
    chkMul(chk, "3B9ACA00", "E8D4A51000", "3635C9ADC5DEA00000", 128)
    chkMul(chk, "25295F0D1", "10", "25295F0D10", 128)
    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "4b66dc33f6acdca5e20890f2a5210000", 128) # overflow

    chkMul(chk, "123456789ABCDEF00", "123456789ABCDEF00", "14b66dc33f6acdca5e20890f2a5210000", 256)

static:
  testMul(ctCheck, ctTest)

suite "Wider unsigned int muldiv coverage":
  testMul(check, test)

#[
suite "Testing unsigned int multiplication implementation":
  test "Multiplication with result fitting in low half":

    let a = 10000.stuint(64)
    let b = 10000.stuint(64)

    check: cast[uint64](a*b) == 100_000_000'u64 # need 27-bits

  test "Multiplication with result overflowing low half":

    let a = 1_000_000.stuint(64)
    let b = 1_000_000.stuint(64)

    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 = 1_000_000_000.stuint(64)
    let b = 1_000_000_000.stuint(64)
    let c = 1_000.stuint(64)

    let x = 1_000_000_000'u64
    let y = 1_000_000_000'u64
    let z = 1_000'u64
    let w = x*y*z

    #check: cast[uint64](a*b*c) == 1_000_000_000_000_000_000_000'u64 # need 70-bits
    check: cast[uint64](a*b*c) == w

  test "Nim v1.0.2 32 bit type inference rule changed":
    let x = 9975492817.stuint(256)
    let y = 16.stuint(256)
    check x * y == 159607885072.stuint(256)
]#