nim-stint/tests/test_uint_divmod.nim

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# Stint
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# 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.
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import ../stint, unittest, test_helpers
template chkDiv(chk: untyped, a, b, c: string, bits: int) =
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chk (fromHex(StUint[bits], a) div fromHex(StUint[bits], b)) == fromHex(StUint[bits], c)
template chkMod(chk: untyped, a, b, c: string, bits: int) =
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chk (fromHex(StUint[bits], a) mod fromHex(StUint[bits], b)) == fromHex(StUint[bits], c)
template chkDivMod(chk: untyped, a, b, c, d: string, bits: int) =
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chk divmod(fromHex(StUint[bits], a), fromHex(StUint[bits], b)) == (fromHex(StUint[bits], c), fromHex(StUint[bits], d))
template testdivmod(chk, tst: untyped) =
tst "operator `div`":
chkDiv(chk, "0", "3", "0", 128)
chkDiv(chk, "1", "3", "0", 128)
chkDiv(chk, "3", "3", "1", 128)
chkDiv(chk, "3", "1", "3", 128)
chkDiv(chk, "FF", "3", "55", 128)
chkDiv(chk, "FFFF", "3", "5555", 128)
chkDiv(chk, "FFFFFFFF", "3", "55555555", 128)
chkDiv(chk, "FFFFFFFFFFFFFFFF", "3", "5555555555555555", 128)
chkDiv(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "3", "55555555555555555555555555555555", 128)
tst "operator `mod`":
chkMod(chk, "0", "3", "0", 128)
chkMod(chk, "1", "3", "1", 128)
chkMod(chk, "3", "3", "0", 128)
chkMod(chk, "3", "1", "0", 128)
chkMod(chk, "FF", "3", "0", 128)
chkMod(chk, "FF", "4", "3", 128)
chkMod(chk, "FFFF", "3", "0", 128)
chkMod(chk, "FFFF", "17", "8", 128)
chkMod(chk, "FFFFFFFF", "3", "0", 128)
chkMod(chk, "FFFFFFFF", "23", "A", 128)
chkMod(chk, "FFFFFFFF", "27", "15", 128)
chkMod(chk, "FFFFFFFFFFFFFFFF", "27", "F", 128)
chkMod(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "27", "15", 128)
tst "operator `divmod`":
chkDivMod(chk, "0", "3", "0", "0", 128)
chkDivMod(chk, "1", "3", "0", "1", 128)
chkDivMod(chk, "3", "3", "1", "0", 128)
chkDivMod(chk, "3", "1", "3", "0", 128)
chkDivMod(chk, "FF", "3", "55", "0", 128)
chkDivMod(chk, "FF", "4", "3F", "3", 128)
chkDivMod(chk, "FFFF", "3", "5555", "0", 128)
chkDivMod(chk, "FFFF", "17", "B21", "8", 128)
chkDivMod(chk, "FFFFFFFF", "3", "55555555", "0", 128)
chkDivMod(chk, "FFFFFFFF", "23", "7507507", "0A", 128)
chkDivMod(chk, "FFFFFFFF", "27", "6906906", "15", 128)
chkDivMod(chk, "FFFFFFFFFFFFFFFF", "27", "690690690690690", "F", 128)
chkDivMod(chk, "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", "27", "6906906906906906906906906906906", "15", 128)
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static:
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testdivmod(ctCheck, ctTest)
suite "Wider unsigned int muldiv coverage":
testdivmod(check, test)
suite "Testing unsigned int division and modulo implementation":
test "Divmod(100, 13) returns the correct result":
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let a = 100.stuint(256)
let b = 13.stuint(256)
let qr = divmod(a, b)
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check qr.quot == 7'u64.u256
check qr.rem == 9'u64.u256
test "Divmod(2^64, 3) returns the correct result":
let a = 1.stuint(128) shl 64
let b = 3.stuint(128)
let qr = divmod(a, b)
let q = qr.quot
let r = qr.rem
check:
q == 6148914691236517205'u64.u128
r == 1'u64.u128
test "Divmod(1234567891234567890, 10) returns the correct result":
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let a = 1234567891234567890'u64.u256
let b = 10'u64.u256
let qr = divmod(a, b)
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let q = qr.quot
let r = qr.rem
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check:
q == 123456789123456789'u64.u256
r == 0'u64.u256
suite "Testing specific failures highlighted by property-based testing":
test "Modulo: 65696211516342324 mod 174261910798982":
let u = 65696211516342324'u64
let v = 174261910798982'u64
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let a = u.u256
let b = v.u256
let z = u mod v
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let tz = a mod b
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check z.u256 == tz
test "Modulo: 15080397990160655 mod 600432699691":
let u = 15080397990160655'u64
let v = 600432699691'u64
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let a = u.u256
let b = v.u256
let z = u mod v
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let tz = a mod b
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check z.u256 == tz
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test "bug #133: SIGFPE":
let a = "115792089237316195423570985008687907852908329466009024615882241056864671687049".u256
let b = "15030568110056696491".u256
let q = a div b
let r = a mod b
check q == "7703773296489151700480904010733627392011592199037677352760".u256
let w = q * b + r
check w == a