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;; Copyright (C) 2017, Regents of the University of Texas
;; Written by Cuong Chau
;; License: A 3-clause BSD license. See the LICENSE file distributed with
;; ACL2.
;; Cuong Chau <ckcuong@cs.utexas.edu>
;; January 2019
(in-package "ADE")
(include-book "../unbound")
;; ======================================================================
;; HALF ADDER
(defconst *half-adder*
'((half-adder
(a b)
(sum carry)
()
((g0 (sum) b-xor (a b))
(g1 (carry) b-and (a b))))))
(defund half-adder& (netlist)
(declare (xargs :guard (alistp netlist)))
(equal (assoc 'half-adder netlist)
(car *half-adder*)))
(local
(defthmd check-half-adder
(and (net-syntax-okp *half-adder*)
(net-arity-okp *half-adder*)
(half-adder& *half-adder*))))
(defun half-adder$outputs (inputs st)
(declare (ignorable st))
(let ((a (car inputs))
(b (cadr inputs)))
(list (f-xor a b)
(f-and a b))))
(defthm half-adder$value
(implies (half-adder& netlist)
(equal (se 'half-adder inputs st netlist)
(half-adder$outputs inputs st)))
:hints (("Goal"
:expand (se 'half-adder inputs st netlist)
:in-theory (enable de-rules half-adder&))))
;; ======================================================================
;; FULL ADDER
(defconst *full-adder*
(cons
'(full-adder
(c a b)
(sum carry)
()
((t0 (sum1 carry1) half-adder (a b))
(t1 (sum carry2) half-adder (sum1 c))
(t2 (carry) b-or (carry1 carry2))))
*half-adder*))
(defund full-adder& (netlist)
(declare (xargs :guard (alistp netlist)))
(and (equal (assoc 'full-adder netlist)
(car *full-adder*))
(half-adder& (delete-to-eq 'full-adder netlist))))
(local
(defthmd check-full-adder
(and (net-syntax-okp *full-adder*)
(net-arity-okp *full-adder*)
(full-adder& *full-adder*))))
(defun full-adder$outputs (inputs st)
(declare (ignorable st))
(let ((c (car inputs))
(a (cadr inputs))
(b (caddr inputs)))
(list (f-xor3 c a b)
(f-or (f-and a b)
(f-and (f-xor a b) c)))))
(defthm full-adder$value
(implies (full-adder& netlist)
(equal (se 'full-adder inputs st netlist)
(full-adder$outputs inputs st)))
:hints (("Goal"
:expand (se 'full-adder inputs st netlist)
:in-theory (enable de-rules
full-adder&
3vp
f-gates))))
;; ======================================================================
;; RIPPLE-CARRY ADDER
;; Ripple-carry adder body generator
(defun ripple-add-body (m n)
(declare (xargs :guard (and (natp m)
(natp n))))
;; m is the current index and n is the number of occurrences.
(if (zp n)
nil
(cons
(list
;; occurrence name
(si 'g m)
;; outputs
(list (si 'sum m)
(si 'carry (1+ m)))
;; inferior module reference
'full-adder
;; inputs
(list (si 'carry m)
(si 'a m)
(si 'b m)))
(ripple-add-body (1+ m) (1- n)))))
(module-generator
ripple-add* (n)
(si 'ripple-add n) ; Name
(cons (si 'carry 0) ; Inputs are
(append (sis 'a 0 n) ; (carry_0 a_0 a_1 ... a_n-1
(sis 'b 0 n))) ; b_0 b_1 ... b_n-1)
(append (sis 'sum 0 n) ; Outputs are
(list (si 'carry n))) ; (sum_0 sum_1 ... sum_n-1 carry_n)
() ; State
(ripple-add-body 0 n) ; Occurrences
(declare (xargs :guard (natp n))))
(defund ripple-add$netlist (n)
(declare (xargs :guard (natp n)))
(cons (ripple-add* n)
*full-adder*))
(defund ripple-add& (netlist n)
(declare (xargs :guard (and (alistp netlist)
(natp n))))
(and (equal (assoc (si 'ripple-add n) netlist)
(ripple-add* n))
(full-adder& (delete-to-eq (si 'ripple-add n)
netlist))))
(local
(defthmd check-ripple-add$netlist-64
(and (net-syntax-okp (ripple-add$netlist 64))
(net-arity-okp (ripple-add$netlist 64))
(ripple-add& (ripple-add$netlist 64) 64))))
(defun ripple-add-body-induct (m n wire-alist st-alist netlist)
(if (zp n)
wire-alist
(ripple-add-body-induct
(1+ m)
(1- n)
(se-occ-bindings 1
(ripple-add-body m n)
wire-alist
st-alist
netlist)
st-alist
netlist)))
(local
(defthm ripple-add$unbound-in-body-sum
(implies (and (natp k)
(natp m)
(< k m))
(unbound-in-body (si 'sum k)
(ripple-add-body m n)))
:hints (("Goal" :in-theory (enable occ-outs)))))
(local
(defthm ripple-add-body$value
(implies (and (full-adder& netlist)
(natp m)
(natp n)
(equal m+n (+ m n))
;; We need the following hypothesis for the case of (zp n)
(3vp (assoc-eq-value (si 'carry m) wire-alist)))
(equal (assoc-eq-values (append (sis 'sum m n)
(list (si 'carry m+n)))
(se-occ (ripple-add-body m n)
wire-alist
st-alist
netlist))
(fv-adder
(assoc-eq-value (si 'carry m) wire-alist)
(assoc-eq-values (sis 'a m n) wire-alist)
(assoc-eq-values (sis 'b m n) wire-alist))))
:hints (("Goal"
:induct (ripple-add-body-induct m n wire-alist st-alist netlist)
:in-theory (enable de-rules
fv-adder
sis)))))
(local
(defthm ripple-add-body$value-m=0
(implies (and (full-adder& netlist)
(natp n)
(3vp (assoc-eq-value (si 'carry 0) wire-alist)))
(equal (assoc-eq-values (append (sis 'sum 0 n)
(list (si 'carry n)))
(se-occ (ripple-add-body 0 n)
wire-alist
st-alist
netlist))
(fv-adder
(assoc-eq-value (si 'carry 0) wire-alist)
(assoc-eq-values (sis 'a 0 n) wire-alist)
(assoc-eq-values (sis 'b 0 n) wire-alist))))))
(defthm ripple-add$value
(implies (and (ripple-add& netlist n)
(natp n)
(3vp c)
(true-listp a)
(true-listp b)
(equal n (len a))
(equal n (len b)))
(equal (se (si 'ripple-add n)
(cons c (append a b))
st
netlist)
(fv-adder c a b)))
:hints (("Goal"
:expand (:free (inputs n)
(se (si 'ripple-add n) inputs st netlist))
:in-theory (e/d* (de-rules
ripple-add&
ripple-add*$destructure)
(de-module-disabled-rules)))))
(defthm ripple-add$value-correct
(implies (and (ripple-add& netlist n)
(natp n)
(equal n (len a))
(booleanp c)
(bv2p a b))
(equal (v-to-nat
(se (si 'ripple-add n)
(cons c (append a b))
st
netlist))
(+ (bool->bit c)
(v-to-nat a)
(v-to-nat b))))
:hints (("Goal" :in-theory (enable bool->bit))))
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