From 6f7b0f5e308675a8c11e2d48482d23f10bb99599 Mon Sep 17 00:00:00 2001
From: plugd <plugd@thelambdalab.xyz>
Date: Sun, 2 Oct 2022 18:02:57 +0200
Subject: [PATCH] Reorganised execution loop to cater for input.

---
 ez.el | 121 +++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 73 insertions(+), 48 deletions(-)

diff --git a/ez.el b/ez.el
index af348a9..7a91e57 100644
--- a/ez.el
+++ b/ez.el
@@ -26,6 +26,13 @@
 
 ;;; Commentary:
 
+;; There are many Z-machine interpreters, but this one is mine.
+;; It only capable of interpreting the subset of Z-code necessary
+;; to run the first Zork game in z3 format.
+;;
+;; It is based entirely on the description of the Z-machine contained
+;; Marnix Klooster's wonderful document, "The Z-machine And How to Emulate It."
+
 ;;; Code:
 
 ;; Utility functions
@@ -312,7 +319,6 @@
 (defun ez-get-zstring (base-addr)
   (cdr (ez-get-zstring-and-length base-addr)))
 
-
 ;; Call stack
 
 (defvar ez-call-stack nil)
@@ -572,157 +578,158 @@
     ((0op #x0B) new_line ez-op-new-line)
     ((var #x06) print_num ez-op-print-num)
     ((var #x05) print_char ez-op-print-char)
-    ((1op #x0A) print_obj ez-op-print-obj)))
+    ((1op #x0A) print_obj ez-op-print-obj)
+    ((var #x04) read ez-op-read)))
 
 (defun ez-op-ret (operands &optional operand-types)
   (let ((retval (car operands)))
     (message "\tReturning value %x" retval)
     (ez-pop-call-stack-frame)
     (ez-set-var (ez-read-pc-byte-and-inc) retval))
-  t)
+  'run)
 
 (defun ez-op-ret-pulled (operands operand-types)
   (let ((retval (ez-routine-stack-pop)))
     (message "\tReturning value %x" retval)
     (ez-op-ret (list retval)))
-  t)
+  'run)
 
 (defun ez-op-rtrue (&optional operands operand-types)
   (ez-op-ret (list 1))
-  t)
+  'run)
 
 (defun ez-op-rfalse (&optional operands operand-types)
   (ez-op-ret (list 0))
-  t)
+  'run)
 
 (defun ez-op-jz (operands operand-types)
   (ez-do-branch (= (car operands) 0))
-  t)
+  'run)
 
 (defun ez-op-je (operands operand-types)
   (ez-do-branch (memq (car operands) (cdr operands)))
-  t)
+  'run)
 
 (defun ez-op-jg (operands operand-types)
   (let ((s1 (ez-decode-signed-operand (car operands) (car operand-types)))
         (s2 (ez-decode-signed-operand (cadr operands) (cadr operand-types))))
     (ez-do-branch (> s1 s2)))
-  t)
+  'run)
 
 (defun ez-op-jl (operands operand-types)
   (let ((s1 (ez-decode-signed-operand (car operands) (car operand-types)))
         (s2 (ez-decode-signed-operand (cadr operands) (cadr operand-types))))
     (ez-do-branch (< s1 s2)))
-  t)
+  'run)
 
 (defun ez-op-inc-jg (operands operand-types)
   (let ((var (car operands)))
     (ez-op-inc (list var))
     (ez-op-jg (cons (ez-get-var var) (cdr operands)) (cons 'w (cdr operand-types))))
-  t)
+  'run)
 
 (defun ez-op-dec-jl (operands operand-types)
   (let ((var (car operands)))
     (ez-op-dec (list var))
     (ez-op-jl (cons (ez-get-var var) (cdr operands)) (cons 'w (cdr operand-types))))
-  t)
+  'run)
 
 (defun ez-op-jin (operands operand-types)
   (let ((obj (car operands))
         (n (cadr operands)))
     (ez-do-branch (or (= n 0)
                       (= n (ez-get-obj-parent obj)))))
-  t)
+  'run)
 
 (defun ez-op-test (operands operand-types)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-do-branch (= (logand a b) b)))
-  t)
+  'run)
 
 (defun ez-op-jump (operands operand-types)
   (let ((offset (if (eq (car operand-types) 'b)
                     (ez-decode-signed-byte (car operands))
                   (ez-decode-signed-word (car operands)))))
     (ez-set-pc (+ (ez-get-pc) offset -2)))
-  t)
+  'run)
 
 (defun ez-op-inc (operands &optional operand-types)
   (let ((var (car operands)))
     (ez-set-var var (mod (+ 1 (ez-get-var var)) #x10000)))
-  t)
+  'run)
 
 (defun ez-op-dec (operands &optional operand-types)
   (let ((var (car operands)))
     (ez-set-var var (mod (+ (ez-get-var var) 1) #x10000)))
-  t)
+  'run)
 
 (defun ez-op-store (operands operand-types)
   (let ((var (car operands))
         (a (cadr operands)))
     (ez-set-var var a))
-  t)
+  'run)
 
 (defun ez-op-load (operands operand-types)
   (let ((var (car operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (ez-get-var var)))
-  t)
+  'run)
 
 (defun ez-op-storew (operands operand-types)
   (let ((baddr (car operands))
         (n (cadr operands))
         (a (caddr operands)))
     (ez-mem-set-word (+ baddr (* 2 n)) a))
-  t)
+  'run)
 
 (defun ez-op-loadw (operands operand-types)
   (let ((baddr (car operands))
         (n (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (ez-mem-ref-word (+ baddr (* 2 n)))))
-  t)
+  'run)
 
 (defun ez-op-storeb (operands operand-types)
   (let ((baddr (car operands))
         (n (cadr operands))
         (a (caddr operands)))
     (ez-mem-set-byte (+ baddr n) a))
-  t)
+  'run)
 
 (defun ez-op-loadb (operands operand-types)
   (let ((baddr (car operands))
         (n (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (ez-mem-ref-byte (+ baddr n))))
-  t)
+  'run)
 
 (defun ez-op-and (operands operand-types)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (logand a b)))
-  t)
+  'run)
 
 (defun ez-op-or (operands operand-types)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (logior a b)))
-  t)
+  'run)
 
 (defun ez-op-add (operands operand-types)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (mod (+ a b) #x10000)))
-  t)
+  'run)
 
 (defun ez-op-sub (operands operand-types)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (mod (+ (- a b) #x10000) #x10000)))
-  t)
+  'run)
 
 (defun ez-op-mul (a b)
   (let ((a (car operands))
         (b (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc) (mod (* a b) #x10000)))
-  t)
+  'run)
 
 (defun ez-op-div (a b)
   (error "Not implemented"))
@@ -744,67 +751,67 @@
         (if (< i n)
             (ez-set-local-var (+ i 1) (elt call-operands i))
           (ez-set-local-var (+ i 1) (ez-mem-ref-word (+ r 1 (* 2 i))))))))
-  t)
+  'run)
 
 (defun ez-op-test-attr (operands operand-types)
   (let ((obj (car operands))
         (attr (cadr operands)))
     (ez-do-branch (= 1 (ez-get-obj-attr obj attr)))
-    t))
+    'run))
 
 (defun ez-op-set-attr (operands operand-types)
   (let ((obj (car operands))
         (attr (cadr operands)))
     (ez-set-obj-attr obj attr 1))
-  t)
+  'run)
 
 (defun ez-op-clear-attr (operands operand-types)
   (let ((obj (car operands))
         (attr (cadr operands)))
     (ez-set-obj-attr obj attr 0))
-  t)
+  'run)
 
 (defun ez-op-get-sibling (operands operand-types)
   (let ((sib (ez-get-obj-sibling (car operands))))
     (ez-set-var (ez-read-pc-byte-and-inc) sib)
     (ez-do-branch (> sib 0)))
-  t)
+  'run)
 
 (defun ez-op-get-child (operands operand-types)
   (let ((child (ez-get-obj-child (car operands))))
     (ez-set-var (ez-read-pc-byte-and-inc) child)
     (ez-do-branch (> child 0)))
-  t)
+  'run)
 
 (defun ez-op-get-parent (operands operand-types)
   (let ((parent (ez-get-obj-parent (car operands))))
     (ez-set-var (ez-read-pc-byte-and-inc) parent))
-  t)
+  'run)
 
 (defun ez-op-remove-obj (operands operand-types)
   (let ((obj (car operands)))
     (ez-remove-obj obj))
-  t)
+  'run)
 
 (defun ez-op-insert-obj (operands operand-types)
   (let ((obj1 (car operands))
         (obj2 (cadr operands)))
     (ez-insert-obj obj1 obj2))
-  t)
+  'run)
 
 (defun ez-op-put-prop (operands operand-types)
   (let* ((obj (car operands))
          (prop (cadr operands))
          (a (caddr operands)))
     (ez-set-obj-prop obj prop a))
-  t)
+  'run)
 
 (defun ez-op-get-prop (operands operand-types)
   (let* ((obj (car operands))
          (prop (cadr operands)))
     (ez-set-var (ez-read-pc-byte-and-inc)
                 (ez-get-obj-prop obj prop)))
-  t)
+  'run)
 
 (defun ez-op-print (operands operand-types)
   (let* ((word-count-and-string (ez-get-zstring-and-length (ez-get-pc)))
@@ -812,36 +819,49 @@
          (string (cdr word-count-and-string)))
     (ez-print string)
     (ez-increment-pc (* 2 word-count)))
-  t)
+  'run)
 
 (defun ez-op-new-line (operands operand-types)
   (ez-print "\n")
-  t)
+  'run)
 
 (defun ez-op-print-num (operands operand-types)
   (let ((s (ez-decode-signed-operand (car operands) (car operand-types))))
     (ez-print (number-to-string s)))
-  t)
+  'run)
 
 (defun ez-op-print-char (operands operand-types)
   (let ((c (car operands)))
     (ez-print (string c)))
-  t)
+  'run)
 
 (defun ez-op-print-obj (operands operand-types)
   (let ((obj (car operands)))
     (ez-print (ez-get-obj-name obj)))
-  t)
+  'run)
+
+(defun ez-op-read (operands operand-types)
+  (let ((baddr1 (car operands))
+        (baddr2 (cadr operands)))
+    )
+  'wait-for-input)
 
 ;; Execution loop
 
-(defun ez-run (filename)
+(defun ez-load-and-run (filename)
   (ez-load-file filename)
   (ez-parse-header)
   (setq ez-call-stack (list (ez-make-call-stack-frame ez-start-pc)))
 
-  (while (ez-execute-instr)))
+  (ez-run))
 
+(defvar ez-machine-state nil
+  "Identifies the current executation state of the Z-machine.")
+
+(defun ez-run ()
+  (setq ez-machine-state 'run)
+  (while (eq ez-machine-state 'run)
+    (setq ez-machine-state (ez-execute-instr))))
 
 ;;; Buffer and I/O
 ;;
@@ -866,6 +886,11 @@
       (goto-char ez-input-marker)
       (insert-before-markers string))))
 
+(defun ez-enter ()
+  (interactive)
+  (with-current-buffer "*ez*"
+    (buffer-substring ez-input-marker (point-max))))
+
 ;; Mode
 
 (defvar ez-mode-map
@@ -886,7 +911,7 @@
     (switch-to-buffer "*ez*")
     (ez-mode)
     (ez-setup-buffer)
-    (ez-run zfile))
+    (ez-load-and-run zfile))
   "Started EZ.")
 
 (defun ez-debug ()
@@ -894,6 +919,6 @@
   (switch-to-buffer "*ez*")
   (ez-mode)
   (ez-setup-buffer)
-  (ez-run "zork1.z3"))
+  (ez-load-and-run "zork1.z3"))
 
 ;;; ez.el ends here
-- 
2.20.1