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style(library/data/bv): Simplify from_bv and bv_mul

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Joe Hendrix 2015-11-30 09:52:25 -08:00 committed by Leonardo de Moura
parent fd1999a97f
commit 3574ad1f11
1 changed files with 9 additions and 13 deletions
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22
library/data/bv.lean
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@ -116,16 +116,17 @@ section arith
definition bv_sub : bv n → bv n → bv n
| x y := pr₂ (bv_sbb x y ff)
definition bv_mul : bv n → bv n → bv n
| (tag x px) y :=
let f := λr b, (let r2 := bv_shl r 1 in cond b (bv_add r2 y) r2) in
foldl f (bv_zero n) x
definition bv_has_zero [instance] : has_zero (bv n) := has_zero.mk (bv_zero n)
definition bv_has_one [instance] : has_one (bv n) := has_one.mk (bv_one n)
definition bv_has_add [instance] : has_add (bv n) := has_add.mk bv_add
definition bv_has_sub [instance] : has_sub (bv n) := has_sub.mk bv_sub
definition bv_has_neg [instance] : has_neg (bv n) := has_neg.mk bv_neg
definition bv_mul : bv n → bv n → bv n
| x y :=
let f := λr b, cond b (r + r + y) (r + r) in
foldl f 0 (to_list x)
definition bv_has_mul [instance] : has_mul (bv n) := has_mul.mk bv_mul
definition bv_ult : bv n → bv n → bool := λx y, pr₁ (bv_sbb x y ff)
@ -150,15 +151,10 @@ end arith
section from_bv
variable {A : Type}
protected definition fold_list_bits [p : has_add A] [q : has_one A]
: list bool → A → A
| [] r := r
| (tt::l) r := fold_list_bits l (r+r+1)
| (ff::l) r := fold_list_bits l (r+r)
-- Convert a bitvector to another number.
definition from_bv [p : has_add A] [q0 : has_zero A] [q1 : has_one A] {w:nat} (v:bv w) : A :=
bv.fold_list_bits (to_list v) 0
definition from_bv [p : has_add A] [q0 : has_zero A] [q1 : has_one A] {n:nat} (v:bv n) : A :=
let f := λr b, cond b (r + r + 1) (r + r) in
foldl f 0 (to_list v)
end from_bv
end bv