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)
- MIT/GNU Scheme (処理系)
計算機プログラムの構造と解釈(Gerald Jay Sussman(原著)、Julie Sussman(原著)、Harold Abelson(原著)、和田 英一(翻訳)、ピアソンエデュケーション、原書: Structure and Interpretation of Computer Programs (MIT Electrical Engineering and Computer Science)(SICP))の5(レジスタ計算機での計算)、5.2(レジスタ計算機シミュレータ)、5.2.3(命令の実行手続きの生成)、assign命令、test、branchおよびgoto命令、その他の命令、部分式の実行手続き、問題 5.11-cを解いてみる。
その他参考書籍
問題 5.11-c.
修正箇所。
コード(BBEdit)
;; 各レジスタの空のスタックを作成しておく
(define (make-new-machine)
(let ((pc (make-register 'pc))
(flag (make-register 'flag))
(stack (make-stack))
(the-instruction-sequence '()))
(let ((the-ops
(list (list 'initialize-stack
(lambda () (stack 'initialize)))))
(register-table
(list (list 'pc pc) (list 'flag flag))))
(define (allocate-register name)
(if (assoc name register-table)
(error "Multiply defined register: " name)
(begin (add-reg-s stack name)
(set! register-table
(cons (list name (make-register name))
register-table))))
'register-allocated)
(define (lookup-register name)
(let ((val (assoc name register-table)))
(if val
(cadr val)
(error "Unknown register:" name))))
(define (execute)
(let ((insts (get-contents pc)))
(if (null? insts)
'done
(begin
((instruction-execution-proc (car insts)))
(execute)))))
(define (dispatch message)
(cond ((eq? message 'start)
(set-contents! pc the-instruction-sequence)
(execute))
((eq? message 'install-instruction-sequence)
(lambda (seq) (set! the-instruction-sequence seq)))
((eq? message 'allocate-register) allocate-register)
((eq? message 'get-register) lookup-register)
((eq? message 'install-operations)
(lambda (ops) (set! the-ops (append the-ops ops))))
((eq? message 'stack) stack)
((eq? message 'operations) the-ops)
(else (error "Unknown request -- MACHINE" message))))
dispatch)))
(define (make-stack)
(let ((s '()))
(define (push reg-name x)
(let ((reg-s (assoc reg-name s)))
(if reg-s
(set-cdr! reg-s (cons x (cdr reg-s)))
(error "Reg-name register is not exists -- PUSH" reg-name))))
(define (pop reg-name)
(let ((reg-s (assoc reg-name s)))
(if reg-s
(if (null? (cdr reg-s))
(error "Empty reg-name stack -- POP" reg-name)
(let ((top (cadr reg-s)))
(set-cdr! reg-s (cddr reg-s))
top))
(error "Regname register is not exists -- POP" reg-name))))
(define (initialize)
(for-each
(lambda (reg-s)
(set-cdr! reg-s '()))
s)
'done)
(define (add-reg-s reg-name)
(if (assoc reg-name s)
(error "already exists reg-name stack -- ADD-REG-S" reg-name)
(set! s (cons (list reg-name) s))))
(define (dispatch message)
(cond ((eq? message 'push) push)
((eq? message 'pop) pop)
((eq? message 'initialize) (initialize))
((eq? message 'add-reg-s) add-reg-s)
(else (error "Unknown request -- STACK"
message))))
dispatch))
(define (pop stack reg-name)
((stack 'pop) reg-name))
(define (push stack reg-name value)
((stack 'push) reg-name value))
(define (add-reg-s stack reg-name)
((stack 'add-reg-s) reg-name))
(define (make-save inst machine stack pc)
(let ((reg-name (stack-inst-reg-name inst)))
(let ((reg (get-register machine reg-name)))
(lambda ()
(push stack reg-name (get-contents reg))
(advance-pc pc)))))
(define (make-restore inst machine stack pc)
(let ((reg-name (stack-inst-reg-name inst)))
(let ((reg (get-register machine reg-name)))
(lambda ()
(set-contents! reg (pop stack reg-name))
(advance-pc pc)))))
全体。
コード(BBEdit)
register_c.scm
(define (make-machine register-names ops controller-text)
(let ((machine (make-new-machine)))
(for-each (lambda (register-name)
((machine 'allocate-register) register-name))
register-names)
((machine 'install-operations) ops)
((machine 'install-instruction-sequence)
(assemble controller-text machine))
machine))
(define (make-register name)
(let ((contents '*unassigned*))
(define (dispatch message)
(cond ((eq? message 'get) contents)
((eq? message 'set)
(lambda (value) (set! contents value)))
(else
(error "Unknown request -- REGISTER" message))))
dispatch))
(define (get-contents register)
(register 'get))
(define (set-contents! register value)
((register 'set) value))
(define (make-stack)
(let ((s '()))
(define (push reg-name x)
(let ((reg-s (assoc reg-name s)))
(if reg-s
(set-cdr! reg-s (cons x (cdr reg-s)))
(error "Reg-name register is not exists -- PUSH" reg-name))))
(define (pop reg-name)
(let ((reg-s (assoc reg-name s)))
(if reg-s
(if (null? (cdr reg-s))
(error "Empty reg-name stack -- POP" reg-name)
(let ((top (cadr reg-s)))
(set-cdr! reg-s (cddr reg-s))
top))
(error "Regname register is not exists -- POP" reg-name))))
(define (initialize)
(for-each
(lambda (reg-s)
(set-cdr! reg-s '()))
s)
'done)
(define (add-reg-s reg-name)
(if (assoc reg-name s)
(error "already exists reg-name stack -- ADD-REG-S" reg-name)
(set! s (cons (list reg-name) s))))
(define (dispatch message)
(cond ((eq? message 'push) push)
((eq? message 'pop) pop)
((eq? message 'initialize) (initialize))
((eq? message 'add-reg-s) add-reg-s)
(else (error "Unknown request -- STACK"
message))))
dispatch))
(define (pop stack reg-name)
((stack 'pop) reg-name))
(define (push stack reg-name value)
((stack 'push) reg-name value))
(define (add-reg-s stack reg-name)
((stack 'add-reg-s) reg-name))
(define (start machine)
(machine 'start))
(define (get-register-contents machine register-name)
(get-contents (get-register machine register-name)))
(define (set-register-contents! machine register-name value)
(set-contents! (get-register machine register-name) value)
'done)
(define (get-register machine reg-name)
((machine 'get-register) reg-name))
(define (make-new-machine)
(let ((pc (make-register 'pc))
(flag (make-register 'flag))
(stack (make-stack))
(the-instruction-sequence '()))
(let ((the-ops
(list (list 'initialize-stack
(lambda () (stack 'initialize)))))
(register-table
(list (list 'pc pc) (list 'flag flag))))
(define (allocate-register name)
(if (assoc name register-table)
(error "Multiply defined register: " name)
(begin (add-reg-s stack name)
(set! register-table
(cons (list name (make-register name))
register-table))))
'register-allocated)
(define (lookup-register name)
(let ((val (assoc name register-table)))
(if val
(cadr val)
(error "Unknown register:" name))))
(define (execute)
(let ((insts (get-contents pc)))
(if (null? insts)
'done
(begin
((instruction-execution-proc (car insts)))
(execute)))))
(define (dispatch message)
(cond ((eq? message 'start)
(set-contents! pc the-instruction-sequence)
(execute))
((eq? message 'install-instruction-sequence)
(lambda (seq) (set! the-instruction-sequence seq)))
((eq? message 'allocate-register) allocate-register)
((eq? message 'get-register) lookup-register)
((eq? message 'install-operations)
(lambda (ops) (set! the-ops (append the-ops ops))))
((eq? message 'stack) stack)
((eq? message 'operations) the-ops)
(else (error "Unknown request -- MACHINE" message))))
dispatch)))
(define (assemble controller-text machine)
(extract-labels controller-text
(lambda (insts labels)
(update-insts! insts labels machine)
insts)))
(define (extract-labels text receive)
(if (null? text)
(receive '() '())
(extract-labels (cdr text)
(lambda (insts labels)
(let ((next-inst (car text)))
(if (symbol? next-inst)
(if (assoc next-inst labels)
(error "Multiply defined label: " next-inst)
(receive insts
(cons (make-label-entry next-inst
insts)
labels)))
(receive (cons (make-instruction next-inst)
insts)
labels)))))))
(define (update-insts! insts labels machine)
(let ((pc (get-register machine 'pc))
(flag (get-register machine 'flag))
(stack (machine 'stack))
(ops (machine 'operations)))
(for-each
(lambda (inst)
(set-instruction-execution-proc!
inst
(make-execution-procedure
(instruction-text inst) labels machine
pc flag stack ops)))
insts)))
(define (make-instruction text)
(cons text '()))
(define (instruction-text inst)
(car inst))
(define (instruction-execution-proc inst)
(cdr inst))
(define (set-instruction-execution-proc! inst proc)
(set-cdr! inst proc))
(define (make-label-entry label-name insts)
(cons label-name insts))
(define (lookup-label labels label-name)
(let ((val (assoc label-name labels)))
(if val
(cdr val)
(error "Undefined label -- ASSEMBLE" label-name))))
(define (make-execution-procedure inst labels machine
pc flag stack ops)
(cond ((eq? (car inst) 'assign)
(make-assign inst machine labels ops pc))
((eq? (car inst) 'test)
(make-test inst machine labels ops flag pc))
((eq? (car inst) 'branch)
(make-branch inst machine labels flag pc))
((eq? (car inst) 'goto)
(make-goto inst machine labels pc))
((eq? (car inst) 'save)
(make-save inst machine stack pc))
((eq? (car inst) 'restore)
(make-restore inst machine stack pc))
((eq? (car inst) 'perform)
(make-perform inst machine labels ops pc))
;; 新しい構文を追加(branchと枝分かれの仕方が逆)
((eq? (car inst) 'branch-not)
(make-branch-not inst machine labels flag pc))
(else (error "Unknown instruction type -- ASSEMBLE"
inst))))
(define (make-assign inst machine labels operations pc)
(let ((target
(get-register machine (assign-reg-name inst)))
(value-exp (assign-value-exp inst)))
(let ((value-proc
(if (operation-exp? value-exp)
(make-operation-exp
value-exp machine labels operations)
(make-primitive-exp
(car value-exp) machine labels))))
(lambda () ; execution procedure for assign
(set-contents! target (value-proc))
(advance-pc pc)))))
(define (assign-reg-name assign-instruction)
(cadr assign-instruction))
(define (assign-value-exp assign-instruction)
(cddr assign-instruction))
(define (advance-pc pc)
(set-contents! pc (cdr (get-contents pc))))
(define (make-test inst machine labels operations flag pc)
(let ((condition (test-condition inst)))
(if (operation-exp? condition)
(let ((condition-proc
(make-operation-exp
condition machine labels operations)))
(lambda ()
(set-contents! flag (condition-proc))
(advance-pc pc)))
(error "Bad TEST instruction -- ASSEMBLE" inst))))
(define (test-condition test-instruction)
(cdr test-instruction))
(define (make-branch inst machine labels flag pc)
(let ((dest (branch-dest inst)))
(if (label-exp? dest)
(let ((insts
(lookup-label labels (label-exp-label dest))))
(lambda ()
(if (get-contents flag)
(set-contents! pc insts)
(advance-pc pc))))
(error "Bad BRANCH instruction -- ASSEMBLE" inst))))
(define (branch-dest branch-instruction)
(cadr branch-instruction))
(define (make-goto inst machine labels pc)
(let ((dest (goto-dest inst)))
(cond ((label-exp? dest)
(let ((insts
(lookup-label labels
(label-exp-label dest))))
(lambda () (set-contents! pc insts))))
((register-exp? dest)
(let ((reg
(get-register machine
(register-exp-reg dest))))
(lambda ()
(set-contents! pc (get-contents reg)))))
(else (error "Bad GOTO instruction -- ASSEMBLE"
inst)))))
(define (goto-dest goto-instruction)
(cadr goto-instruction))
(define (make-save inst machine stack pc)
(let ((reg-name (stack-inst-reg-name inst)))
(let ((reg (get-register machine reg-name)))
(lambda ()
(push stack reg-name (get-contents reg))
(advance-pc pc)))))
(define (make-restore inst machine stack pc)
(let ((reg-name (stack-inst-reg-name inst)))
(let ((reg (get-register machine reg-name)))
(lambda ()
(set-contents! reg (pop stack reg-name))
(advance-pc pc)))))
(define (stack-inst-reg-name stack-instruction)
(cadr stack-instruction))
(define (make-perform inst machine labels operations pc)
(let ((action (perform-action inst)))
(if (operation-exp? action)
(let ((action-proc
(make-operation-exp
action machine labels operations)))
(lambda ()
(action-proc)
(advance-pc pc)))
(error "Bad PERFORM instruction -- ASSEMBLE" inst))))
(define (perform-action inst) (cdr inst))
(define (make-branch-not inst machine labels flag pc)
(let ((dest (branch-not-dest inst)))
(if (label-exp? dest)
(let ((insts
(lookup-label labels (label-exp-label dest))))
(lambda ()
(if (get-contents flag)
(advance-pc pc)
(set-contents! pc insts))))
(error "Bad BRANCH-NOT instruction -- ASSEMBLE" inst))))
(define (branch-not-dest branch-not-instruction)
(cadr branch-not-instruction))
(define (make-primitive-exp exp machine labels)
(cond ((constant-exp? exp)
(let ((c (constant-exp-value exp)))
(lambda () c)))
((label-exp? exp)
(let ((insts
(lookup-label labels
(label-exp-label exp))))
(lambda () insts)))
((register-exp? exp)
(let ((r (get-register machine
(register-exp-reg exp))))
(lambda () (get-contents r))))
(else
(error "Unknown expression type -- ASSEMBLE" exp))))
(define (tagged-list? exp tag)
(if (pair? exp)
(eq? (car exp) tag)
false))
(define (register-exp? exp) (tagged-list? exp 'reg))
(define (register-exp-reg exp) (cadr exp))
(define (constant-exp? exp) (tagged-list? exp 'const))
(define (constant-exp-value exp) (cadr exp))
(define (label-exp? exp) (tagged-list? exp 'label))
(define (label-exp-label exp) (cadr exp))
(define (make-operation-exp exp machine labels operations)
(let ((op (lookup-prim (operation-exp-op exp) operations))
(aprocs
(map (lambda (e)
(if (label-exp? e)
(error
"Cannot apply op to lbael -- MAKE-OPERATION-EXP" e)
(make-primitive-exp e machine labels)))
(operation-exp-operands exp))))
(lambda ()
(apply op (map (lambda (p) (p)) aprocs)))))
(define (operation-exp? exp)
(and (pair? exp) (tagged-list? (car exp) 'op)))
(define (operation-exp-op operation-exp)
(cadr (car operation-exp)))
(define (operation-exp-operands operation-exp)
(cdr operation-exp))
(define (lookup-prim symbol operations)
(let ((val (assoc symbol operations)))
(if val
(cadr val)
(error "Unknown operation -- ASSEMBLE" symbol))))
元のrestoreとの違いを確認。
入出力結果(Terminal, REPL(Read, Eval, Print, Loop))
$ scheme
MIT/GNU Scheme running under MacOSX
Type `^C' (control-C) followed by `H' to obtain information about interrupts.
Copyright (C) 2011 Massachusetts Institute of Technology
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Image saved on Saturday October 26, 2013 at 11:02:50 PM
Release 9.1.1 || Microcode 15.3 || Runtime 15.7 || SF 4.41 || LIAR/C 4.118
Edwin 3.116
1 ]=> (load "./register_c.scm")
;Loading "./register_c.scm"... done
;Value: lookup-prim
1 ]=>
(define machine
(make-machine
'(x y)
'()
'((assign x (const 1))
(assign y (const 2))
(save y)
(save x)
(restore y))))
;Value: machine
1 ]=> (start machine)
;Value: done
1 ]=> (get-register-contents machine 'y)
;Value: 2
1 ]=> (load "./register.scm")
;Loading "./register.scm"... done
;Value: lookup-prim
1 ]=>
(define machine
(make-machine
'(x y)
'()
'((assign x (const 1))
(assign y (const 2))
(save y)
(save x)
(restore y))))
;Value: machine
1 ]=> (start machine)
;Value: done
1 ]=> (get-register-contents machine 'y)
;Value: 1
1 ]=> ^D
End of input stream reached.
Moriturus te saluto.
$
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