24 lines
679 B
Text
24 lines
679 B
Text
/-
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Copyright (c) 2019 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura
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-/
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prelude
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import init.data.nat.basic init.data.nat.div init.coe
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namespace nat
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def bitwise (f : bool → bool → bool) : nat → nat → nat | n m :=
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if n = 0 then (if f ff tt then m else 0)
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else if m = 0 then (if f tt ff then n else 0)
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else
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let n' := n / 2 in
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let m' := m / 2 in
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let b₁ := n % 2 = 1 in
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let b₂ := m % 2 = 1 in
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let r := bitwise n' m' in
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if f b₁ b₂ then bit1 r else bit0 r
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def land : nat → nat → nat := bitwise band
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def lor : nat → nat → nat := bitwise bor
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end nat
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