計算機プログラムの構造と解釈[第2版]
(翔泳社)
ハロルド エイブルソン (著) ジュリー サスマン (著)
ジェラルド・ジェイ サスマン (著)
Harold Abelson (原著) Julie Sussman (原著)
Gerald Jay Sussman (原著) 和田 英一 (翻訳)
開発環境
- OS X Mavericks - Apple(OS)
- Emacs (CUI)、BBEdit - Bare Bones Software, Inc. (GUI) (Text Editor)
- Scheme (プログラミング言語)
- Gauche (処理系)
計算機プログラムの構造と解釈[第2版](ハロルド エイブルソン (著)、ジュリー サスマン (著)、ジェラルド・ジェイ サスマン (著)、Harold Abelson (原著)、Julie Sussman (原著)、Gerald Jay Sussman (原著)、和田 英一 (翻訳)、翔泳社、原書: Structure and Interpretation of Computer Programs (MIT Electrical Engineering and Computer Science)(SICP))の3(標準部品化力、オブジェクトおよび状態)、3.3(可変データでのモデル化)、3.3.4(デジタル回路のシミュレーター)、回線の表現、次第書き、シミュレーションの例、問題 3.31.を解いてみる。
その他参考書籍
- Instructor's Manual to Accompany Structure & Interpretation of Computer Programs
- プログラミングGauche (Kahuaプロジェクト (著), 川合 史朗 (監修), オライリージャパン)
問題 3.31.
初期化が必要なのは、各回線のシグナルの値の初期値(0)を変更するために必要。追加した新しいアクション手続きが回線に追加された際に、この手続きを直ちに走らせないと各回線のシグナルの値が0のままで、正しく動作しない。
半加算器の例を、初期化しない場合どうなるかをトレース。
(define (probe name wire)
(add-action! wire
(lambda ()
(newline)
(display name)
(display " ")
(display (current-time the-agenda))
(display " New-value = ")
(display (get-signal wire)))))
(define the-agenda (make-agenda))
;; the-agenda 空っぽ
(define inverter-delay 2)
(define and-gate-delay 3)
(define or-gate-delay 5)
(define input-1 (make-wire))
;; input-1: signal-value 0, action-procedures '()
(define input-2 (make-wire))
;; input-2: signal-value 0, action-procedures '()
(define sum (make-wire))
;; sum: signal-value 0, action-procedures '()
(define carry (make-wire))
;; carry: signal-value 0, action-procedures '()
(prob 'sum sum)
sum 0 New-value = 0
(probe 'carry carry)
sum 0 New-value = 0
(half-adder input-1 input-2 sum carry)
;; d: signal-value 0, action-procedures '()
;; e: signal-value 0, action-procedures '()
(or-gate input-1 input-2 d)
(add-action! input-1 (lambda ()
(let ((new-value
(logical-or (get-signal input-1)
(get-signal input-2))))
(after-delay 5 (lambda ()
(set-signal! d new-value))))))
;; input-1:
;; signal-value 0
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
(add-action! input-2 or-action-procedure)
;; input-2:
;; signal-value 0
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
(and-gate input-1 input-2 carry)
(add-action! input-1 (lambda ()
(let ((new-value
(logical-and (get-signal input-1)
(get-signal input-2))))
(after-delay 3
(lambda ()
(set-signal! carry new-value))))))
;; input-1:
;; signal-value 0
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-and (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! carry new-value)))))
;; (lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
(add-action! input-2 (lambda ()
(let ((new-value
(logical-and (get-signal input-1)
(get-signal input-2))))
(after-delay 3
(lambda ()
(set-signal! carry new-value))))))
;; input-2:
;; signal-value 0
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-and (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! carry new-value)))))
;; (lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
(inverter carry e)
(add-action! carry (lambda ()
(let ((new-value
(logical-not (get-signal carry))))
(after-delay 2
(lambda ()
(set-signal! e new-value))))))
;; carry:
;; signal-value 0
;; action-procedures '((lambda ()
;; (let ((new-value
;; (logical-not (get-signal carry))))
;; (after-delay 2
;; (lambda ()
;; (set-signal! e new-value)))))
;; (lambda ()
;; (newline)
;; (display 'carry)
;; (display " ")
;; (display (current-time carry))
;; (display " New-value = ")
;; (display (get-signal carry))))
(and-gate d e sum)
(add-action! d (lambda ()
(let ((new-value
(logical-and (get-signal d)
(get-signal e))))
(after-delay 3
(lambda ()
(set-signal! sum new-value))))))
;; d:
;; signal-value 0
;; action-procedures '((lambda ()
;; (let ((new-value
;; (logical-and (get-signal d)
;; (get-signal e))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! sum new-value))))))
(add-action! e (lambda ()
(let ((new-value
(logical-and (get-signal d)
(get-signal e))))
(after-delay 3
(lambda ()
(set-signal! sum new-value))))))
;; e:
;; signal-value 0
;; action-procedures '((lambda ()
;; (let ((new-value
;; (logical-and (get-signal d)
;; (get-signal e))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! sum new-value))))))
ok
;; input-1:
;; signal-value 0
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-and (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! carry new-value)))))
;; (lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
(set-signal! input-1 1)
(set! signval-value 1)
;; input-1:
;; signal-value 1
;; action-procedures ((lambda ()
;; (let ((new-value
;; (logical-and (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! carry new-value)))))
;; (lambda ()
;; (let ((new-value
;; (logical-or (get-signal input-1)
;; (get-signal input-2))))
;; (after-delay 5 (lambda ()
;; (set-signal! d new-value))))))
;; input-2:
;; signal-value 0
(call-each action-procedures)
;; new-value 0
(after-delay 3
(lambda ()
(set-signal! carry 0)))
;; the-agenda
;; 時間0
;; 時間3, (lambda () (set-signal! carry 0))
;; new-value 1
(after-delay 5
(lambda ()
(set-signal! d 1)))
;; the-agenda
;; 時間0
;; 時間3、(lambda () (set-signal! carry 0))
;; 時間5, (lambda () (set-signal! d 1))
done
(propagate)
;; first-item 時間3、(lambda () (set-signal! carry 0))
;; carry:
;; signal-value 0
(set-signal! carry 0)
;; d:
;; signal-value 0
(set-signal! d 1)
(set! signal-value 1)
;; d:
;; signal-value 1
;; action-procedures '((lambda ()
;; (let ((new-value
;; (logical-and (get-signal d)
;; (get-signal e))))
;; (after-delay 3
;; (lambda ()
;; (set-signal! sum new-value))))))
;; e:
;; signal-value 0
(call-each action-procedures)
((lambda ()
(let ((new-value (get-signal d)
(get-signal e)))
(after-delay 3
(lambda ()
(set-signal! sum new-value))))))
;; new-value 0
(after-delay 3
(lambda ()
(set-signal! sum 0)))
;; the-agenda
;; 時間0
;; 時間3、(lambda () (set-signal! carry 0))
;; 時間5, (lambda () (set-signal! d 1))
;; 時間3, (lambda () (set-signal sum 0))
done
;; 各回線のシグナル値
;; input-1 1
;; input-2 0
;; sum 0
;; carry 0
;; 本来なら、input-1 1, input-2 0なら、sum 1, carry 0とならなければならない
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