122 lines
3.4 KiB
Nim
122 lines
3.4 KiB
Nim
# Stint
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# Copyright 2018 Status Research & Development GmbH
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# Licensed under either of
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#
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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#
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import ../stint, unittest
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suite "Testing signed int multiplication implementation":
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test "Multiplication with result fitting in low half":
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let a = 10000.stint(64)
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let b = 10000.stint(64)
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check: cast[int64](a*b) == 100_000_000'i64 # need 27-bits
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test "Multiplication with result overflowing low half":
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let a = 1_000_000.stint(64)
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let b = 1_000_000.stint(64)
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check: cast[int64](a*b) == 1_000_000_000_000'i64 # need 40 bits
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test "Multiplication with result fitting in low half - opposite signs":
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let a = -10000.stint(64)
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let b = 10000.stint(64)
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check:
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cast[int64](a*b) == -100_000_000'i64 # need 27-bits
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cast[int64](b*a) == -100_000_000'i64
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test "Multiplication with result overflowing low half - opposite signs":
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let a = -1_000_000.stint(64)
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let b = 1_000_000.stint(64)
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check:
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cast[int64](a*b) == -1_000_000_000_000'i64 # need 40 bits
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cast[int64](b*a) == -1_000_000_000_000'i64
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test "Multiplication with result fitting in low half - both negative":
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let a = -10000.stint(64)
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let b = -10000.stint(64)
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check: cast[int64](a*b) == 100_000_000'i64 # need 27-bits
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test "Multiplication with result overflowing low half - both negative":
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let a = -1_000_000.stint(64)
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let b = -1_000_000.stint(64)
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check: cast[int64](a*b) == 1_000_000_000_000'i64 # need 40 bits
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suite "Testing signed int division and modulo implementation":
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test "Divmod(100, 13) returns the correct result":
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let a = 100.stint(64)
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let b = 13.stint(64)
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let qr = divmod(a, b)
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check: cast[int64](qr.quot) == 7'i64
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check: cast[int64](qr.rem) == 9'i64
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test "Divmod(-100, 13) returns the correct result":
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let a = -100.stint(64)
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let b = 13.stint(64)
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let qr = divmod(a, b)
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check: cast[int64](qr.quot) == -100'i64 div 13
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check: cast[int64](qr.rem) == -100'i64 mod 13
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test "Divmod(100, -13) returns the correct result":
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let a = 100.stint(64)
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let b = -13.stint(64)
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let qr = divmod(a, b)
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check: cast[int64](qr.quot) == 100'i64 div -13
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check: cast[int64](qr.rem) == 100'i64 mod -13
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test "Divmod(-100, -13) returns the correct result":
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let a = -100.stint(64)
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let b = -13.stint(64)
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let qr = divmod(a, b)
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check: cast[int64](qr.quot) == -100'i64 div -13
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check: cast[int64](qr.rem) == -100'i64 mod -13
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# test "Divmod(2^64, 3) returns the correct result":
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# let a = 1.stint(128) shl 64
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# let b = 3.stint(128)
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# let qr = divmod(a, b)
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# let q = cast[UintImpl[uint64]](qr.quot)
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# let r = cast[UintImpl[uint64]](qr.rem)
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# check: q.lo == 6148914691236517205'u64
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# check: q.hi == 0'u64
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# check: r.lo == 1'u64
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# check: r.hi == 0'u64
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test "Divmod(1234567891234567890, 10) returns the correct result":
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let a = cast[Stint[64]](1234567891234567890'i64)
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let b = cast[Stint[64]](10'i64)
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let qr = divmod(a, b)
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let q = cast[int64](qr.quot)
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let r = cast[int64](qr.rem)
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check: q == 123456789123456789'i64
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check: r == 0'i64
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