48 lines
1.6 KiB
Nim
48 lines
1.6 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 ./datatypes, ./conversion, ./as_signed_words
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func `+`*(x, y: IntImpl): IntImpl {.inline.}=
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# Addition for multi-precision signed int.
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type SubTy = type x.lo
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result.lo = x.lo + y.lo
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result.hi = (result.lo < y.lo).toSubtype(SubTy) + x.hi + y.hi
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when compileOption("boundChecks"):
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if unlikely(
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((result.most_significant_word xor x.most_significant_word) >= 0) or
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((result.most_significant_word xor y.most_significant_word) >= 0)
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):
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return
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raise newException(OverflowError, "Addition overflow")
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func `+=`*(x: var IntImpl, y: IntImpl) {.inline.}=
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## In-place addition for multi-precision signed int.
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x = x + y
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func `-`*(x, y: IntImpl): IntImpl {.inline.}=
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# Substraction for multi-precision signed int.
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type SubTy = type x.lo
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result.lo = x.lo - y.lo
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result.hi = x.hi - y.hi - (x.lo < y.lo).toSubtype(SubTy)
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when compileOption("boundChecks"):
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if unlikely(
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((result.most_significant_word xor x.most_significant_word) >= 0) or
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((result.most_significant_word xor (not y).most_significant_word) >= 0)
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):
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return
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raise newException(OverflowError, "Substraction underflow")
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func `-=`*(x: var IntImpl, y: IntImpl) {.inline.}=
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## In-place substraction for multi-precision signed int.
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x = x - y
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