99 lines
3.3 KiB
Nim
99 lines
3.3 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, ./bitops2_priv, ./uint_bitwise_ops
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func `not`*(x: IntImpl): IntImpl {.inline.}=
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## Bitwise complement of unsigned integer x
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applyHiLo(x, `not`)
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func `or`*(x, y: IntImpl): IntImpl {.inline.}=
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## `Bitwise or` of numbers x and y
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applyHiLo(x, y, `or`)
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func `and`*(x, y: IntImpl): IntImpl {.inline.}=
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## `Bitwise and` of numbers x and y
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applyHiLo(x, y, `and`)
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func `xor`*(x, y: IntImpl): IntImpl {.inline.}=
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## `Bitwise xor` of numbers x and y
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applyHiLo(x, y, `xor`)
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func convertImpl[T: SomeInteger](x: SomeInteger): T {.compileTime.} =
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cast[T](x)
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func convertImpl[T: IntImpl|UintImpl](x: IntImpl|UintImpl): T {.compileTime.} =
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result.hi = convertImpl[type(result.hi)](x.hi)
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result.lo = x.lo
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template convert[T](x: UintImpl|IntImpl|SomeInteger): T =
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when nimvm:
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# this is a workaround Nim VM inability to cast
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# something non integer
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convertImpl[T](x)
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else:
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cast[T](x)
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func `shl`*(x: IntImpl, y: SomeInteger): IntImpl {.inline.}=
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## Compute the `shift left` operation of x and y
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# Note: inlining this poses codegen/aliasing issue when doing `x = x shl 1`
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# TODO: would it be better to reimplement this with words iteration?
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const halfSize: type(y) = bitsof(x) div 2
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type HiType = type(result.hi)
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if y == 0:
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return x
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elif y == halfSize:
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result.hi = convert[HiType](x.lo)
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elif y < halfSize:
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# `shr` in this equation uses uint version
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result.hi = (x.hi shl y) or convert[HiType](x.lo shr (halfSize - y))
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result.lo = x.lo shl y
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else:
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result.hi = convert[HiType](x.lo shl (y - halfSize))
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template createShr(name, operator: untyped) =
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template name(x, y: SomeInteger): auto =
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operator(x, y)
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func name*(x: IntImpl, y: SomeInteger): IntImpl {.inline.}=
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## Compute the `arithmetic shift right` operation of x and y
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## Similar to C standard, result is undefined if y is bigger
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## than the number of bits in x.
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const halfSize: type(y) = bitsof(x) div 2
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type LoType = type(result.lo)
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if y == 0:
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return x
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elif y == halfSize:
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result.lo = convert[LoType](x.hi)
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result.hi = name(x.hi, halfSize-1)
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elif y < halfSize:
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result.lo = (x.lo shr y) or convert[LoType](x.hi shl (halfSize - y))
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result.hi = name(x.hi, y)
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else:
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result.lo = convert[LoType](name(x.hi, (y - halfSize)))
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result.hi = name(x.hi, halfSize-1)
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template nimVersionIs(comparator: untyped, major, minor, patch: int): bool =
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comparator(NimMajor * 100 + NimMinor * 10 + NimPatch, major * 100 + minor * 10 + patch)
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when nimVersionIs(`>=`, 0, 20, 0):
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createShr(shrOfShr, `shr`)
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elif nimVersionIs(`<`, 0, 20, 0) and defined(nimAshr):
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createShr(shrOfAshr, ashr)
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else:
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{.error: "arithmetic right shift is not defined for this Nim version".}
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template `shr`*(a, b: typed): untyped =
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when nimVersionIs(`>=`, 0, 20, 0):
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shrOfShr(a, b)
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elif nimVersionIs(`<`, 0, 20, 0) and defined(nimAshr):
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shrOfAShr(a, b)
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