09a5b34931
This PR adjusts the experimental module system to make `private` the default visibility modifier in `module`s, introducing `public` as a new modifier instead. `public section` can be used to revert the default for an entire section, though this is more intended to ease gradual adoption of the new semantics such as in `Init` (and soon `Std`) where they should be replaced by a future decl-by-decl re-review of visibilities.
63 lines
1.5 KiB
Text
63 lines
1.5 KiB
Text
/-
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Copyright (c) 2024 Lean FRO, LLC. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Joe Hendrix, Wojciech Nawrocki, Leonardo de Moura, Mario Carneiro, Alex Keizer, Harun Khan, Abdalrhman M Mohamed
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-/
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module
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prelude
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public import Init.Data.Fin.Basic
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public section
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set_option linter.missingDocs true
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/-!
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This module exists to provide the very basic `BitVec` definitions required for
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`Init.Data.UInt.BasicAux`.
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-/
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namespace BitVec
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section Nat
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/--
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The bitvector with value `i mod 2^n`.
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-/
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@[expose, match_pattern]
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protected def ofNat (n : Nat) (i : Nat) : BitVec n where
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toFin := Fin.ofNat (2^n) i
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instance instOfNat : OfNat (BitVec n) i where ofNat := .ofNat n i
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/-- Return the bound in terms of toNat. -/
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theorem isLt (x : BitVec w) : x.toNat < 2^w := x.toFin.isLt
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grind_pattern isLt => x.toNat, 2^w
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end Nat
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section arithmetic
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/--
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Adds two bitvectors. This can be interpreted as either signed or unsigned addition modulo `2^n`.
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Usually accessed via the `+` operator.
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SMT-LIB name: `bvadd`.
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-/
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@[expose]
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protected def add (x y : BitVec n) : BitVec n := .ofNat n (x.toNat + y.toNat)
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instance : Add (BitVec n) := ⟨BitVec.add⟩
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/--
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Subtracts one bitvector from another. This can be interpreted as either signed or unsigned subtraction
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modulo `2^n`. Usually accessed via the `-` operator.
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-/
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@[expose]
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protected def sub (x y : BitVec n) : BitVec n := .ofNat n ((2^n - y.toNat) + x.toNat)
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instance : Sub (BitVec n) := ⟨BitVec.sub⟩
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end arithmetic
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end BitVec
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