Skip to content
Create a gist now

Instantly share code, notes, and snippets.

DCPU-16 Lisp implementation
(defpackage #:dcpu-16
(:use #:cl)
#:make-ram #:ram-read #:ram-write #:ram-size
#:execute #:debug
#:load-program #:assemble-program
#:set #:add #:sub #:mul
#:div #:mod #:shl #:shr
#:and #:bor #:xor #:ife
#:ifn #:ifg #:ifb #:jsr
(in-package #:dcpu-16)
;;;; DCPU-16
;;; Implementation of
(deftype word () '(unsigned-byte 16))
;;; Memory
(defun make-ram (&optional (size #x10000))
"Return a new memory object with SIZE words. All words are
initially set to zero."
(make-array size
:element-type 'word
:initial-element 0))
(defun ram-read (n ram)
"Read the Nth word in RAM and return it."
(aref ram n))
(defun ram-write (value n ram)
"Write the VALUE to the Nth word in RAM."
(setf (aref ram n)
(logand value #xFFFF)))
(defun ram-size (ram)
"Return the size of the RAM in words."
(array-dimension ram 0))
;;; Registers
(defun make-register-file ()
"Return a new register file, i.e. storage for the DCPU-16's
registers. Registers are all initially set to zero."
(make-array 11
:element-type 'word
:initial-element 0))
(defun reg-index (name)
"Return the index of the register named NAME in the register file."
(position name '(a b c x y z i j pc sp o)))
(defun reg-read (name file)
"Read the value of the register named NAME in FILE."
(aref file (reg-index name)))
(defun reg-write (value name file)
"Write VALUE to the register named NAME in FILE."
(setf (aref file (reg-index name))
(logand value #xFFFF)))
;;; Instruction execution and debugging
(defvar *register-file* nil)
(defvar *ram* nil)
(defvar *cycles-count* nil)
(defvar *skip-instruction* nil)
(defun set-o (value)
(reg-write value 'o *register-file*))
(defun get-pc ()
(reg-read 'pc *register-file*))
(defun set-pc (value)
(reg-write value 'pc *register-file*))
(defmacro saving-pc (&body forms)
(let ((pc (gensym)))
`(let ((,pc (get-pc)))
(progn ,@forms)
(set-pc ,pc)))))
(defun get-sp ()
(reg-read 'sp *register-file*))
(defun set-sp (value)
(reg-write value 'sp *register-file*))
(defun skip-next-instruction ()
(incf *cycles-count*)
(setf *skip-instruction* t))
(defun reset-skip-instruction ()
(setf *skip-instruction* nil))
(defun consume-word ()
(let ((pc (get-pc)))
(set-pc (1+ pc))
(ram-read pc *ram*)))
(defun execute-set (operand-1 operand-2)
(operand-write (operand-read operand-2) operand-1))
(defun execute-add (operand-1 operand-2)
(let ((sum (+ (operand-read operand-1) (operand-read operand-2))))
(set-o (if (> sum #xFFFF) 1 0))
(operand-write sum operand-1)))
(defun execute-sub (operand-1 operand-2)
(let ((diff (- (operand-read operand-1) (operand-read operand-2))))
(set-o (if (< diff 0) #xFFFF 0))
(operand-write diff operand-1)))
(defun execute-mul (operand-1 operand-2)
(let ((prod (* (operand-read operand-1) (operand-read operand-2))))
(set-o (ash prod -16))
(operand-write prod operand-1)))
(defun execute-div (operand-1 operand-2)
(let ((a (operand-read operand-1))
(b (operand-read operand-2)))
(cond ((zerop b)
(set-o 0)
(operand-write 0 operand-1))
(set-o (floor (ash a 16) b))
(operand-write (floor a b) operand-1)))))
(defun execute-mod (operand-1 operand-2)
(let ((a (operand-read operand-1))
(b (operand-read operand-2)))
(if (zerop b)
(operand-write 0 operand-1)
(operand-write (mod a b) operand-1))))
(defun execute-shl (operand-1 operand-2)
(let ((shifted (ash (operand-read operand-1) (operand-read operand-2))))
(set-o (ash shifted -16))
(operand-write shifted operand-1)))
(defun execute-shr (operand-1 operand-2)
(let ((a (operand-read operand-1))
(b (operand-read operand-2)))
(set-o (ash (ash a 16) (- b)))
(operand-write (ash a (- b)) operand-1)))
(defun execute-and (operand-1 operand-2)
(operand-write (logand (operand-read operand-1) (operand-read operand-2))
(defun execute-bor (operand-1 operand-2)
(operand-write (logior (operand-read operand-1) (operand-read operand-2))
(defun execute-xor (operand-1 operand-2)
(operand-write (logxor (operand-read operand-1) (operand-read operand-2))
(defun execute-ife (operand-1 operand-2)
(when (/= (operand-read operand-1) (operand-read operand-2))
(defun execute-ifn (operand-1 operand-2)
(when (= (operand-read operand-1) (operand-read operand-2))
(defun execute-ifg (operand-1 operand-2)
(when (<= (operand-read operand-1) (operand-read operand-2))
(defun execute-ifb (operand-1 operand-2)
(when (zerop (logand (operand-read operand-1) (operand-read operand-2)))
(defun execute-jsr (operand-1)
(let ((sp (get-sp)))
(set-sp (1- sp))
(ram-write (get-pc) (1- sp) *ram*)
(set-pc (operand-read operand-1))))
(defun process-instruction (basic-function non-basic-function)
(let* ((word (consume-word))
(bits (extract-basic-opcode-bits word)))
(if (zerop bits)
(funcall non-basic-function
(extract-non-basic-opcode-bits word))
(read-operand word 10))
(funcall basic-function
(find-basic-opcode-by-bits bits)
(read-operand word 4)
(read-operand word 10)))))
(defun extract-basic-opcode-bits (word)
(logand word #x0F))
(defun extract-non-basic-opcode-bits (word)
(logand (ash word -4) #x3F))
(defun extract-operand-bits (word base)
(logand (ash word (- base)) #x3F))
(defun execute-instruction ()
(process-instruction #'execute-basic-instruction
(defun execute-basic-instruction (opcode operand-1 operand-2)
(cond (*skip-instruction*
(t (funcall (opcode-execute-function opcode) operand-1 operand-2)
(incf *cycles-count* (opcode-cycles-count opcode))
(incf *cycles-count* (operand-cycles-count (car operand-1)))
(incf *cycles-count* (operand-cycles-count (car operand-2))))))
(defun execute-non-basic-instruction (opcode operand-1)
(cond (*skip-instruction*
(t (funcall (opcode-execute-function opcode) operand-1)
(incf *cycles-count* (opcode-cycles-count opcode))
(incf *cycles-count* (operand-cycles-count (car operand-1))))))
(defun read-operand (word base)
(let* ((bits (extract-operand-bits word base))
(operand (find-operand-by-bits bits)))
(cons operand
(ecase (operand-length operand)
(0 nil)
(1 (consume-word))))))
(defun operand-read (operand-and-word)
(operand-read-1 (car operand-and-word) (cdr operand-and-word)))
(defun operand-write (value operand-and-word)
(operand-write-1 value (car operand-and-word) (cdr operand-and-word)))
(defun operand-format (operand-and-word)
(operand-format-1 (car operand-and-word) (cdr operand-and-word)))
(defun execute (ram)
(let ((*register-file* (make-register-file))
(*ram* ram)
(*cycles-count* 0)
(*skip-instruction* nil)
(last-pc -1))
(set-sp #xFFFF)
(if (= last-pc (get-pc))
(setf last-pc (get-pc))))))
(defun debug (ram)
(let ((*register-file* (make-register-file))
(*ram* ram)
(*cycles-count* 0)
(*skip-instruction* nil))
(set-sp #xFFFF)
(catch 'debug-exit
(let ((command (prompt-debug-command)))
(when (consp command)
(apply (command-function (car command))
(cdr command))))))))
(defun command-function (command)
(or (get command 'debug-function)
(unknown-command command)))
(defun unknown-command (command)
(lambda (&rest args)
(format t "Unknown command ~S (with args ~S).~%" command args)))
(defmacro define-debug-command ((&rest aliases) (&rest params) &body forms)
`(let ((fn (lambda (,@params) ,@forms)))
(dolist (alias ',aliases)
(setf (get alias 'debug-function) fn))
(define-debug-command (p step) ()
(define-debug-command (d words) (offset)
(print-words (ram-words offset *ram*) offset))
(define-debug-command (g step-until) (&optional offset)
(loop for pc = (get-pc)
and last-pc = -1 then pc
until (or (= pc last-pc) (and offset (= pc offset)))
do (execute-instruction)))
(define-debug-command (u disasm) (&optional (n 2))
(loop repeat n
do (format t "~4,'0X: ~A~%" (get-pc) (current-instruction)))))
(define-debug-command (q bye quit) ()
(throw 'debug-exit nil))
(defun print-debug-info ()
(print-register-file *register-file*)
(format t "Cycles: ~D Instruction: ~A ~:[~;SKIPPING~]~%"
(saving-pc (current-instruction))
(defun print-words (words &optional (base-offset 0))
(loop for i from 0
for word = (pop words)
while word
do (when (zerop (mod i 8))
(format t "~&~4,'0X: " (+ base-offset i)))
(format t "~4,'0X " word)
finally (terpri)))
(defun ram-words (offset ram)
(loop repeat 16
for i from offset
when (< i (ram-size ram))
collect (ram-read i ram)))
(defun print-register-file (file)
(loop for reg in '(a b c x y z i j pc sp o)
do (format t "~A: ~4,'0X " reg (reg-read reg file))))
(defun prompt-debug-command ()
(format t "> ")
(read (make-concatenated-stream
(make-string-input-stream "(")
(make-string-input-stream (read-line))
(make-string-input-stream ")"))))
(defun current-instruction ()
(process-instruction #'current-basic-instruction
(defun current-basic-instruction (opcode operand-1 operand-2)
(list (opcode-mnemonic opcode)
(operand-format operand-1)
(operand-format operand-2)))
(defun current-non-basic-instruction (opcode operand-1)
(list (opcode-mnemonic opcode)
(operand-format operand-1)))
(defun load-program (words ram &optional (offset 0))
(dolist (word words)
(ram-write word offset ram)
(incf offset))
;;; Assembler
(defun make-labels-map ()
"Return an empty labels-map. A labels-map maps labels to
(defun extend-labels-map (label offset labels-map)
"Extend a LABELS-MAP with a LABEL-OFFSET mapping."
(acons label offset labels-map))
(defun lookup-label-offset (label labels-map)
"Map a LABEL to its offset. If no such mapping exists, return NIL."
(cdr (assoc label labels-map)))
(defun subst-offsets-for-labels (instructions labels-map)
"Replace the labels referenced in the list of INSTRUCTIONS with
their corresponding offsets in accordance with LABELS-MAP."
(sublis labels-map instructions))
(defun instruction-op (instruction)
"Return the instruction's operator."
(car instruction))
(defun instruction-a (instruction)
"Return the instruction's first operand."
(cadr instruction))
(defun instruction-b (instruction)
"Return the instruction's second operand."
(caddr instruction))
(defun assemble-instruction (instruction)
"Assemble a single instruction, returning the corresponding list of
(if (basic-instruction-p instruction)
(assemble-basic-instruction instruction)
(assemble-non-basic-instruction instruction)))
(defun assemble-basic-instruction (instruction)
"Assemble a basic instruction, returning a list of words."
(append (list (basic-instruction-word instruction))
(instruction-operand-words (instruction-a instruction))
(instruction-operand-words (instruction-b instruction))))
(defun basic-instruction-word (instruction)
"Return the basic instruction's first word."
(logior (ash (basic-instruction-opcode-bits (instruction-op instruction)) 0)
(ash (instruction-operand-bits (instruction-a instruction)) 4)
(ash (instruction-operand-bits (instruction-b instruction)) 10)))
(defun assemble-non-basic-instruction (instruction)
"Assemble a non-basic instruction, returning a list of words."
(append (list (non-basic-instruction-word instruction))
(instruction-operand-words (instruction-a instruction))))
(defun non-basic-instruction-word (instruction)
"Return the non-basic instruction's first word."
(logior (ash 0 0)
(ash (non-basic-instruction-opcode-bits (instruction-op instruction)) 4)
(ash (instruction-operand-bits (instruction-a instruction)) 10)))
(defclass opcode ()
((mnemonic :initarg :mnemonic :reader opcode-mnemonic)
(bits :initarg :bits :reader opcode-bits)
(cycles-count :initarg :cycles-count :reader opcode-cycles-count)
(execute-function :initarg :execute-function :reader opcode-execute-function)))
(defclass basic-opcode (opcode)
(defclass non-basic-opcode (opcode)
(defclass opcode-index ()
((by-mnemonic :initarg :by-mnemonic :reader opcode-index-by-mnemonic)
(basic-by-bits :initarg :basic-by-bits :reader opcode-index-basic-by-bits)
(non-basic-by-bits :initarg :non-basic-by-bits :reader opcode-index-non-basic-by-bits)))
(defun make-opcode-index (opcodes)
(let ((by-mnemonic (make-hash-table))
(basic-by-bits (make-hash-table))
(non-basic-by-bits (make-hash-table)))
(dolist (opcode opcodes)
(setf (gethash (opcode-mnemonic opcode) by-mnemonic) opcode)
(setf (gethash (opcode-bits opcode)
(etypecase opcode
(basic-opcode basic-by-bits)
(non-basic-opcode non-basic-by-bits)))
(make-instance 'opcode-index
:by-mnemonic by-mnemonic
:basic-by-bits basic-by-bits
:non-basic-by-bits non-basic-by-bits)))
(defvar *opcode-index*
(list (make-instance 'basic-opcode :mnemonic 'set :bits #x01 :cycles-count 1 :execute-function 'execute-set)
(make-instance 'basic-opcode :mnemonic 'add :bits #x02 :cycles-count 2 :execute-function 'execute-add)
(make-instance 'basic-opcode :mnemonic 'sub :bits #x03 :cycles-count 2 :execute-function 'execute-sub)
(make-instance 'basic-opcode :mnemonic 'mul :bits #x04 :cycles-count 2 :execute-function 'execute-mul)
(make-instance 'basic-opcode :mnemonic 'div :bits #x05 :cycles-count 3 :execute-function 'execute-div)
(make-instance 'basic-opcode :mnemonic 'mod :bits #x06 :cycles-count 3 :execute-function 'execute-mod)
(make-instance 'basic-opcode :mnemonic 'shl :bits #x07 :cycles-count 2 :execute-function 'execute-shl)
(make-instance 'basic-opcode :mnemonic 'shr :bits #x08 :cycles-count 2 :execute-function 'execute-shr)
(make-instance 'basic-opcode :mnemonic 'and :bits #x09 :cycles-count 1 :execute-function 'execute-and)
(make-instance 'basic-opcode :mnemonic 'bor :bits #x0A :cycles-count 1 :execute-function 'execute-bor)
(make-instance 'basic-opcode :mnemonic 'xor :bits #x0B :cycles-count 1 :execute-function 'execute-xor)
(make-instance 'basic-opcode :mnemonic 'ife :bits #x0C :cycles-count 2 :execute-function 'execute-ife)
(make-instance 'basic-opcode :mnemonic 'ifn :bits #x0D :cycles-count 2 :execute-function 'execute-ifn)
(make-instance 'basic-opcode :mnemonic 'ifg :bits #x0E :cycles-count 2 :execute-function 'execute-ifg)
(make-instance 'basic-opcode :mnemonic 'ifb :bits #x0F :cycles-count 2 :execute-function 'execute-ifb)
(make-instance 'non-basic-opcode :mnemonic 'jsr :bits #x01 :cycles-count 2 :execute-function 'execute-jsr))))
(defun find-opcode-by-mnemonic (mnemonic)
(gethash mnemonic (opcode-index-by-mnemonic *opcode-index*)))
(defun find-basic-opcode-by-bits (bits)
(gethash bits (opcode-index-basic-by-bits *opcode-index*)))
(defun find-non-basic-opcode-by-bits (bits)
(gethash bits (opcode-index-non-basic-by-bits *opcode-index*)))
(defun basic-instruction-p (instruction)
"Return true if the instruction is a basic one, and false
(let ((opcode (find-opcode-by-mnemonic (instruction-op instruction))))
(typep opcode 'basic-opcode)))
(defun basic-instruction-opcode-bits (op)
"Return opcode bits for a basic instruction's operator."
(let ((opcode (find-opcode-by-mnemonic op)))
(check-type opcode basic-opcode)
(opcode-bits opcode)))
(defun non-basic-instruction-opcode-bits (op)
"Return the opcode bits for a non-basic instruction's operator."
(let ((opcode (find-opcode-by-mnemonic op)))
(check-type opcode non-basic-opcode)
(opcode-bits opcode)))
(defclass operand ()
((cycles-count :initarg :cycles-count :reader operand-cycles-count)
(bits :initarg :bits :reader operand-bits)))
(defgeneric operand-test-p (expr operand))
(defgeneric operand-words (expr operand))
(defgeneric operand-read-1 (operand word))
(defgeneric operand-write-1 (value operand word))
(defgeneric operand-length (operand))
(defgeneric operand-format-1 (operand word))
(defclass operand-no-words-mixin ()
(defmethod operand-words (expr (operand operand-no-words-mixin))
(declare (ignore expr))
(defmethod operand-length ((operand operand-no-words-mixin))
(defclass operand-symbol-mixin ()
((symbol :initarg :symbol :reader operand-symbol)))
(defmethod operand-test-p (expr (operand operand-symbol-mixin))
(eq expr (operand-symbol operand)))
(defmethod operand-format-1 ((operand operand-symbol-mixin) word)
(declare (ignore word))
(operand-symbol operand))
(defclass register-operand (operand-no-words-mixin operand-symbol-mixin operand)
(:default-initargs :cycles-count 0))
(defmethod operand-read-1 ((operand register-operand) word)
(declare (ignore word))
(reg-read (operand-symbol operand) *register-file*))
(defmethod operand-write-1 (value (operand register-operand) word)
(declare (ignore word))
(reg-write value (operand-symbol operand) *register-file*))
(defclass reg-ref-operand (operand-no-words-mixin operand)
((symbol :initarg :symbol :reader operand-symbol))
(:default-initargs :cycles-count 0))
(defmethod operand-test-p (expr (operand reg-ref-operand))
(and (consp expr)
(eq (car expr) (operand-symbol operand))))
(defmethod operand-read-1 ((operand reg-ref-operand) word)
(declare (ignore word))
(let ((offset (reg-read (operand-symbol operand) *register-file*)))
(ram-read offset *ram*)))
(defmethod operand-write-1 (value (operand reg-ref-operand) word)
(declare (ignore word))
(let ((offset (reg-read (operand-symbol operand) *register-file*)))
(ram-write value offset *ram*)))
(defmethod operand-format-1 ((operand reg-ref-operand) word)
(declare (ignore word))
(list (operand-symbol operand)))
(defclass add-reg-ref-operand (operand)
((symbol :initarg :symbol :reader operand-symbol))
(:default-initargs :cycles-count 1))
(defmethod operand-test-p (expr (operand add-reg-ref-operand))
(and (consp expr)
(eq (car expr) '+)
(or (eq (cadr expr) (operand-symbol operand))
(eq (caddr expr) (operand-symbol operand)))))
(defmethod operand-words (expr (operand add-reg-ref-operand))
(let ((a (cadr expr))
(b (caddr expr)))
(if (integerp a)
(list a)
(list b))))
(defun add-reg-ref-offset (operand word)
(let ((reg (reg-read (operand-symbol operand) *register-file*)))
(logand (+ reg word) #xFFFF)))
(defmethod operand-read-1 ((operand add-reg-ref-operand) word)
(ram-read (add-reg-ref-offset operand word) *ram*))
(defmethod operand-write-1 (value (operand add-reg-ref-operand) word)
(ram-write value (add-reg-ref-offset operand word) *ram*))
(defmethod operand-length ((operand add-reg-ref-operand))
(defmethod operand-format-1 ((operand add-reg-ref-operand) word)
(list '+ (operand-symbol operand) word))
(defclass pop-operand (operand-no-words-mixin operand-symbol-mixin operand)
(:default-initargs :cycles-count 0))
(defmethod operand-read-1 ((operand pop-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(set-sp (1+ sp))
(ram-read sp *ram*)))
(defmethod operand-write-1 (value (operand pop-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(set-sp (1+ sp))
(ram-write value sp *ram*)))
(defclass peek-operand (operand-no-words-mixin operand-symbol-mixin operand)
(:default-initargs :cycles-count 0))
(defmethod operand-read-1 ((operand peek-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(ram-read sp *ram*)))
(defmethod operand-write-1 (value (operand peek-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(ram-write value sp *ram*)))
(defclass push-operand (operand-no-words-mixin operand-symbol-mixin operand)
(:default-initargs :cycles-count 0))
(defmethod operand-read-1 ((operand push-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(set-sp (1- sp))
(ram-read (1- sp) *ram*)))
(defmethod operand-write-1 (value (operand push-operand) word)
(declare (ignore word))
(let ((sp (get-sp)))
(set-sp (1- sp))
(ram-write value (1- sp) *ram*)))
(defclass ref-operand (operand)
(:default-initargs :cycles-count 1))
(defmethod operand-test-p (expr (operand ref-operand))
(consp expr))
(defmethod operand-words (expr (operand ref-operand))
(defmethod operand-read-1 ((operand ref-operand) word)
(ram-read word *ram*))
(defmethod operand-write-1 (value (operand ref-operand) word)
(ram-write value word *ram*))
(defmethod operand-length ((operand ref-operand))
(defmethod operand-format-1 ((operand ref-operand) word)
(list word))
(defclass literal-operand (operand)
(:default-initargs :cycles-count 1))
(defmethod operand-test-p (expr (operand literal-operand))
(integerp expr))
(defmethod operand-words (expr (operand literal-operand))
(list expr))
(defmethod operand-read-1 ((operand literal-operand) word)
(defmethod operand-write-1 (value (operand literal-operand) word)
(declare (ignore value word)))
(defmethod operand-length ((operand literal-operand))
(defmethod operand-format-1 ((operand literal-operand) word)
;;; Small literal operands are no good at the moment because they
;;; confuse labels mapping.
(defclass small-literal-operand (operand-no-words-mixin operand)
(:default-initargs :cycles-count 0))
(defmethod operand-test-p (expr (operand small-literal-operand))
(and (integerp expr)
(= expr (- (operand-bits operand) #x20))))
(defmethod operand-read-1 ((operand small-literal-operand) word)
(declare (ignore word))
(- (operand-bits operand) #x20))
(defmethod operand-write-1 (value (operand small-literal-operand) word)
(declare (ignore value word)))
(defmethod operand-format-1 ((operand small-literal-operand) word)
(declare (ignore word))
(- (operand-bits operand) #x20))
(defclass operand-index ()
((list :initarg :list :reader operand-index-list)
(by-bits :initarg :by-bits :reader operand-index-by-bits)))
(defun make-operand-index (operands)
(let ((by-bits (make-hash-table)))
(dolist (operand operands)
(setf (gethash (operand-bits operand) by-bits) operand))
(make-instance 'operand-index
:list operands
:by-bits by-bits)))
(defvar *operand-index*
(list (make-instance 'register-operand :symbol 'a :bits #x00)
(make-instance 'register-operand :symbol 'b :bits #x01)
(make-instance 'register-operand :symbol 'c :bits #x02)
(make-instance 'register-operand :symbol 'x :bits #x03)
(make-instance 'register-operand :symbol 'y :bits #x04)
(make-instance 'register-operand :symbol 'z :bits #x05)
(make-instance 'register-operand :symbol 'i :bits #x06)
(make-instance 'register-operand :symbol 'j :bits #x07)
(make-instance 'reg-ref-operand :symbol 'a :bits #x08)
(make-instance 'reg-ref-operand :symbol 'b :bits #x09)
(make-instance 'reg-ref-operand :symbol 'c :bits #x0A)
(make-instance 'reg-ref-operand :symbol 'x :bits #x0B)
(make-instance 'reg-ref-operand :symbol 'y :bits #x0C)
(make-instance 'reg-ref-operand :symbol 'z :bits #x0D)
(make-instance 'reg-ref-operand :symbol 'i :bits #x0E)
(make-instance 'reg-ref-operand :symbol 'j :bits #x0F)
(make-instance 'add-reg-ref-operand :symbol 'a :bits #x10)
(make-instance 'add-reg-ref-operand :symbol 'b :bits #x11)
(make-instance 'add-reg-ref-operand :symbol 'c :bits #x12)
(make-instance 'add-reg-ref-operand :symbol 'x :bits #x13)
(make-instance 'add-reg-ref-operand :symbol 'y :bits #x14)
(make-instance 'add-reg-ref-operand :symbol 'z :bits #x15)
(make-instance 'add-reg-ref-operand :symbol 'i :bits #x16)
(make-instance 'add-reg-ref-operand :symbol 'j :bits #x17)
(make-instance 'pop-operand :symbol 'pop :bits #x18)
(make-instance 'peek-operand :symbol 'peek :bits #x19)
(make-instance 'push-operand :symbol 'push :bits #x1A)
(make-instance 'register-operand :symbol 'sp :bits #x1B)
(make-instance 'register-operand :symbol 'pc :bits #x1C)
(make-instance 'register-operand :symbol 'o :bits #x1D)
(make-instance 'ref-operand :bits #x1E)
(make-instance 'literal-operand :bits #x1F))))
(defun find-operand-for-expression (expr)
(let ((list (operand-index-list *operand-index*)))
(or (find-if (lambda (operand) (operand-test-p expr operand)) list)
(find-if (lambda (operand) (typep operand 'literal-operand)) list))))
(defun find-operand-by-bits (bits)
(or (gethash bits (operand-index-by-bits *operand-index*))
(error "Can't find operand with bits ~S." bits)))
(defun instruction-operand-words (arg)
"Return the list of additional words for an operand."
(operand-words arg (find-operand-for-expression arg)))
(defun instruction-operand-bits (arg)
"Return the bits representing an operand."
(operand-bits (find-operand-for-expression arg)))
(defun instruction-operand-length (arg)
"Return the length of an instruction's operand."
(operand-length (find-operand-for-expression arg)))
(defun instruction-length (instruction)
"Return the length of an instruction, in words."
(if (basic-instruction-p instruction)
(+ (instruction-operand-length (instruction-a instruction))
(instruction-operand-length (instruction-b instruction))
(+ (instruction-operand-length (instruction-a instruction))
(defun assemble-program (program &optional (base-offset 0))
"Assemble a sequence of instructions and labels, returning the
corresponding list of words."
(mappend #'assemble-instruction (program-instructions program base-offset)))
(defun program-instructions (program base-offset)
(subst-offsets-for-labels (remove-labels program)
(build-labels-map program base-offset)))
(defun mappend (function list)
(if (null list)
(append (funcall function (car list))
(mappend function (cdr list)))))
(defun build-labels-map (program base-offset)
"Build up a labels-map for the supplied PROGRAM, with starting
offset of BASE-OFFSET."
(labels ((iter (subprogram labels-map offset)
(cond ((null subprogram) labels-map)
((symbolp (car subprogram))
(iter (cdr subprogram)
(extend-labels-map (car subprogram) offset labels-map)
(iter (cdr subprogram)
(+ offset (instruction-length (car subprogram))))))))
(iter program (make-labels-map) base-offset)))
(defun remove-labels (program)
"Remove labels from a program, returning a list of instructions."
(remove-if #'symbolp program))
;;;; Test vector
(defvar *program*
'((set a #x30)
(set (#x1000) #x20)
(sub a (#x1000))
(ifn a #x10)
(set pc crash)
(set i 10)
(set a #x2000)
(set (+ #x2000 i) (a))
(sub i 1)
(ifn i 0)
(set pc loop)
(set x #x04)
(jsr test-sub)
(set pc crash)
(shl x 4)
(set pc pop)
(set pc crash)))
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Something went wrong with that request. Please try again.