31 lines
1 KiB
Text
31 lines
1 KiB
Text
/-
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Copyright (c) 2018 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.uint init.platform init.data.fin
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def usize_sz : nat := (2:nat) ^ system.platform.nbits
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def usize : Type := fin usize_sz
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instance : decidable_eq usize :=
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fin.decidable_eq usize_sz
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theorem usize_sz_pos : usize_sz > 0 :=
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show 0 < (2:nat) ^ system.platform.nbits, from
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nat.pos_pow_of_pos _ (nat.zero_lt_bit0 nat.one_ne_zero)
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def usize.of_nat (a : nat) : usize :=
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⟨a % usize_sz, nat.mod_lt _ usize_sz_pos⟩
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instance : has_zero usize := ⟨usize.of_nat 0⟩
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instance : has_one usize := ⟨usize.of_nat 1⟩
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instance : has_add usize := ⟨fin.add⟩
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instance : has_sub usize := ⟨fin.sub⟩
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instance : has_mul usize := ⟨fin.mul⟩
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instance : has_mod usize := ⟨fin.mod⟩
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instance : has_modn usize := ⟨fin.modn⟩
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instance : has_div usize := ⟨fin.div⟩
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instance : has_lt usize := ⟨fin.lt⟩
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instance : has_le usize := ⟨fin.le⟩
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