; assembler, part 3
(define (sprintf fmt . args)
(define (escape cs)
(define (octal? c) (char<=? #\0 c #\7))
(define (c->o c) (- (char->integer c) 48))
(cond ((null? cs) (error 'escape "incomplete"))
((not (char=? (car cs) #\\)) (values (car cs) (cdr cs)))
((null? (cdr cs)) (error 'escape "malformed"))
((char=? (cadr cs) #\b) (values #\backspace (cddr cs)))
((char=? (cadr cs) #\f) (values #\page (cddr cs)))
((char=? (cadr cs) #\n) (values #\newline (cddr cs)))
((char=? (cadr cs) #\r) (values #\return (cddr cs)))
((char=? (cadr cs) #\t) (values #\tab (cddr cs)))
((octal? (cadr cs))
(let loop ((k 3) (cs (cdr cs)) (oct 0))
(if (and (positive? k) (pair? cs) (octal? (car cs)))
(loop (- k 1) (cdr cs) (+ (* oct 8) (c->o (car cs))))
(values (integer->char oct) cs))))
(else (values (cadr cs) (cddr cs)))))
(define (specifier cs arg)
(define (c->d c) (- (char->integer c) 48))
(define (justify str left? pad? width)
(let ((len (string-length str)))
(cond ((<= width len) str)
(left? (string-append str (make-string (- width len) #\space)))
((and pad? (not left?)) (string-append (make-string (- width len) #\0) str))
(else (string-append (make-string (- width len) #\space) str)))))
(define (rnd num prec)
(if prec (/ (round (* num (expt 10 prec))) (expt 10 prec)) num))
(define (trunc num) (inexact->exact (truncate num)))
(let ((cs (cdr cs)) (left? #f) (pad? #f) (width 0) (prec #f))
(when (and (pair? cs) (char=? (car cs) #\-))
(set! left? #t) (set! cs (cdr cs)))
(when (and (pair? cs) (char=? (car cs) #\0))
(set! pad? #t) (set! cs (cdr cs)))
(do () ((or (null? cs) (not (char-numeric? (car cs)))))
(set! width (+ (* width 10) (c->d (car cs)))) (set! cs (cdr cs)))
(when (and (pair? cs) (char=? (car cs) #\.))
(set! cs (cdr cs)) (set! prec 0)
(do () ((or (null? cs) (not (char-numeric? (car cs)))))
(set! prec (+ (* prec 10) (c->d (car cs)))) (set! cs (cdr cs))))
(if (null? cs) (error 'specifier "incomplete")
(case (car cs)
((#\c) (values (justify (string (integer->char arg)) left? #f width) (cdr cs)))
((#\d) (values (justify (number->string (trunc arg)) left? pad? width) (cdr cs)))
((#\f) (values (justify (number->string (rnd arg prec)) left? pad? width) (cdr cs)))
((#\o) (values (justify (number->string (trunc arg) 8) left? pad? width) (cdr cs)))
((#\s) (values (justify (if prec (substring arg 0 prec) arg) left? #f width) (cdr cs)))
((#\x) (values (justify (number->string (trunc arg) 16) left? pad? width) (cdr cs)))
((#\%) (values "%" cs))
(else (error 'specifier "unsupported"))))))
(let loop ((cs (string->list fmt)) (args args) (out (list)))
(cond ((null? cs)
(if (pair? args) (error 'printf "too many arguments")
(list->string (reverse out))))
((char=? (car cs) #\\)
(call-with-values (lambda () (escape cs))
(lambda (c rest) (loop rest args (cons c out)))))
((char=? (car cs) #\%)
(if (null? (cdr cs)) (error 'sprintf "incomplete specifier")
(if (char=? (cadr cs) #\%) (loop (cddr cs) args (cons #\% out))
(if (null? args) (error 'printf "not enough arguments")
(call-with-values (lambda () (specifier cs (car args)))
(lambda (str rest)
(loop rest (cdr args)
(append (reverse (string->list str)) out))))))))
(else (loop (cdr cs) args (cons (car cs) out))))))
(define (printf fmt . args) (display (apply sprintf fmt args)))
(define labels (list))
(define opcodes '(("const" . 0) ("get" . 1) ("put" . 2)
("ld" . 3) ("st" . 4) ("add" . 5) ("sub" . 6)
("jpos" . 7) ("jz" . 8) ("j" . 9) ("halt" . 10)))
(define (split line)
(define (skip-blanks)
(let loop ()
(if (or (null? line) (not (char-whitespace? (car line)))) #f
(begin (set! line (cdr line)) (loop)))))
(define (get-string)
(let loop ((str (list)))
(if (or (null? line) (char-whitespace? (car line)))
(list->string (reverse str))
(let ((c (car line)))
(set! line (cdr line))
(loop (cons c str))))))
(let* ((lbl (get-string)) (_ (skip-blanks))
(opc (get-string)) (_ (skip-blanks))
(obj (get-string)) (_ (skip-blanks)))
(values lbl opc obj (list->string line))))
(define (asm1 file-name) ; first-pass
(set! labels (list))
(with-input-from-file file-name (lambda ()
(let loop ((k 0) (line (read-line)) (lines (list)))
(if (eof-object? line) (reverse lines)
(if (or (string=? line "") (char=? (string-ref line 0) #\#))
(loop k (read-line) lines)
(call-with-values
(lambda () (split (string->list line)))
(lambda (lbl opc obj cmt)
(when (not (string=? lbl ""))
(set! labels (cons (cons lbl k) labels)))
(loop (+ k 1) (read-line)
(cons (vector k lbl opc obj cmt) lines))))))))))
(define (asm2 lines) ; second pass
(let ((mem (make-vector 1000 0)))
(do ((lines lines (cdr lines))) ((null? lines) mem)
(let ((num (vector-ref (car lines) 0))
(opc (vector-ref (car lines) 2))
(obj (vector-ref (car lines) 3)))
(vector-set! mem num (+ (* (cdr (assoc opc opcodes)) 1000)
(if (assoc obj labels) (cdr (assoc obj labels))
(if (not (string=? obj "")) (string->number obj)
0))))))))
(define (sim mem)
(let loop ((pc 0) (acc 0))
(let ((addr (modulo (vector-ref mem pc) 1000))
(code (quotient (vector-ref mem pc) 1000)))
(case code
((1) (loop (+ pc 1) (read))) ; get
((2) (display acc) (newline) (loop (+ pc 1) acc)) ; put
((3) (loop (+ pc 1) (vector-ref mem addr))) ; ld
((4) (vector-set! mem addr acc) (loop (+ pc 1) acc)) ; st
((5) (loop (+ pc 1) (+ acc (vector-ref mem addr)))) ; add
((6) (loop (+ pc 1) (- acc (vector-ref mem addr)))) ; sub
((7) (loop (if (positive? acc) addr (+ pc 1)) acc)) ; jpos
((8) (loop (if (zero? acc) addr (+ pc 1)) acc)) ; jz
((9) (loop addr acc)) ; j
((10) (if #f #f)) ; halt
(else (error 'sim "unrecognized command"))))))
(define (widths lines)
(apply vector
(map (lambda (xs) (apply max xs))
(apply map list
(map (lambda (line)
(map string-length (cdr (vector->list line))))
lines)))))
(define (listing file-name)
(let* ((lines (asm1 file-name))
(mem (asm2 lines))
(widths (widths lines)))
(define (wid n)
(string-append "%-" (number->string (vector-ref widths n)) "s "))
(with-input-from-file file-name
(lambda ()
(let loop ((k 0) (line (read-line)) (lines lines))
(when (not (eof-object? line))
(if (or (string=? line "")
(char=? (string-ref line 0) #\#))
(begin (printf "%s\n" line) (loop k (read-line) lines))
(begin (printf "%03d: " k)
(printf "%05d " (vector-ref mem k))
(printf (wid 0) (vector-ref (car lines) 1))
(printf (wid 1) (vector-ref (car lines) 2))
(printf (wid 2) (vector-ref (car lines) 3))
(printf (wid 3) (vector-ref (car lines) 4))
(printf "\n")
(loop (+ k 1) (read-line) (cdr lines))))))))))
(listing "program.asm")