+ (let* ((player (car players))
+ (other-players (cdr players))
+ (ptrs (player-ptrs player))
+ (new-ptrs (execute-instr (car ptrs) (player-name player))))
+ (if (null? new-ptrs)
+ (run other-players (- steps-left 1))
+ (begin
+ (player-set-ptrs! player (append (cdr ptrs) new-ptrs))
+ (run (append other-players (list player)) (- steps-left 1))))))))
+
+(define (execute-instr ptr name)
+ (let* ((instr (core-get ptr))
+ (A-ptr (eval-operand (instr 'A-mode) (instr 'A-num) ptr))
+ (B-ptr (eval-operand (instr 'B-mode) (instr 'B-num) ptr))
+ (modifier (instr 'modifier)))
+ (case (instr 'opcode)
+ ((DAT)
+ '()) ;Game over, man, game over!
+ ((MOV)
+ (if (eq? modifier 'I)
+ ((core-get B-ptr) 'copy-from! (core-get A-ptr) name)
+ (combine A-ptr B-ptr modifier name (lambda (x y) y)))
+ (list (addr+ ptr 1)))
+ ((ADD)
+ (combine-and-store A-ptr B-ptr modifier name addr+)
+ (list (addr+ ptr 1)))
+ ((SUB)
+ (combine-and-store A-ptr B-ptr modifier name
+ (lambda (x y) (addr+ x (- y))))
+ (list (addr+ ptr 1)))
+ ((MUL)
+ (combine-and-store A-ptr B-ptr modifier name
+ (lambda (x y) (modulo (* (addr+ x core-size)
+ (addr+ y core-size))
+ core-size)))
+ (list (addr+ ptr 1)))
+ ((DIV)
+ (condition-case
+ (begin
+ (combine-and-store A-ptr B-ptr modifier name
+ (lambda (x y) (quotient (addr x core-size)
+ (addr y core-size))))
+ (list (addr+ ptr 1)))
+ ((exn arithmetic) '())))
+ ((MOD)
+ (condition-case
+ (begin
+ (combine-and-store A-ptr B-ptr modifier name
+ (lambda (x y) (remainder (addr x core-size)
+ (addr y core-size))))
+ (list (addr+ ptr 1)))
+ ((exn arithmetic) '())))
+ ((JMP)
+ (list (addr+ ptr ((core-get A-ptr) 'A-num))))
+ ((JMZ)
+ (list (addr+ ptr (if (instr-zero? B-ptr modifier #f)
+ ((core-get A-ptr) 'A-num)
+ 1))))
+ ((JMN)
+ (list (addr+ ptr (if (not (instr-zero? B-ptr modifier #f))
+ ((core-get A-ptr) 'A-num)
+ 1))))
+ ((DJN)
+ (list (addr+ ptr (if (not (instr-zero? B-ptr modifier #t))
+ ((core-get A-ptr) 'A-num)
+ 1))))
+ ((SEQ CMP)
+ (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier =) 2 1))))
+ ((SNE)
+ (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier =) 1 2))))
+ ((SLT)
+ (list (addr+ ptr (if (compare-instrs A-ptr B-ptr modifier <) 2 1))))
+ ((SPL)
+ (list (addr+ ptr 1) (addr+ ptr ((core-get A-ptr) 'A-num))))
+ ((NOP)
+ (list (addr+ ptr 1)))
+ (else
+ (error "Unrecognised opcode" (instr 'opcode))))))
+
+(define (compare-instrs A-ptr B-ptr modifier test)
+ (let ((A-instr (core-get A-ptr))
+ (B-instr (core-get B-ptr)))
+ (case modifier
+ ((A) (test (A-instr 'A-num) (B-instr 'A-num)))
+ ((B) (test (A-instr 'B-num) (B-instr 'B-num)))
+ ((AB) (test (A-instr 'A-num) (B-instr 'B-num)))
+ ((BA) (test (A-instr 'B-num) (B-instr 'A-num)))
+ ((F) (and
+ (test (A-instr 'A-num) (B-instr 'A-num))
+ (test (A-instr 'B-num) (B-instr 'B-num))))
+ ((X) (and
+ (test (A-instr 'A-num) (B-instr 'B-num))
+ (test (A-instr 'B-num) (B-instr 'A-num))))
+ ((I) (and
+ (if (eq? test =)
+ (and
+ (eq? (A-instr 'opcode) (B-instr 'opcode))
+ (eq? (A-instr 'modifier) (B-instr 'modifier))
+ (eq? (A-instr 'A-mode) (B-instr 'B-mode))
+ (eq? (A-instr 'B-mode) (B-instr 'A-mode)))
+ #t)
+ (test (A-instr 'A-num) (B-instr 'B-num))
+ (test (A-instr 'B-num) (B-instr 'A-num)))))))
+
+(define (instr-zero? ptr modifier decrement)
+ (let ((instr (core-get ptr)))
+ (case modifier
+ ((A AB)
+ (if decrement (instr 'set-A-num! (addr+ (instr 'A-num) -1)))
+ (= 0 (instr 'A-num)))
+ ((A AB)
+ (if decrement (instr 'set-B-num! (addr+ (instr 'B-num) -1)))
+ (= 0 (instr 'B-num)))
+ ((X I F)
+ (if decrement
+ (begin
+ (instr 'set-A-num! (addr+ (instr 'A-num) -1))
+ (instr 'set-B-num! (addr+ (instr 'B-num) -1))))
+ (and (= 0 (instr 'A-num))
+ (= 0 (instr 'B-num)))))))
+
+(define (combine-and-store A-ptr B-ptr modifier name f)
+ (case modifier
+ ((A) ((core-get B-ptr) 'set-A-num!
+ (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num)) name))
+ ((B) ((core-get B-ptr) 'set-B-num!
+ (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
+ ((AB) ((core-get B-ptr) 'set-B-num!
+ (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))
+ ((BA) ((core-get B-ptr) 'set-A-num!
+ (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name))
+ ((F I) ((core-get B-ptr) 'set-A-num!
+ (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'A-num))) name
+ ((core-get B-ptr) 'set-B-num!
+ (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'B-num)) name))
+ ((X) ((core-get B-ptr) 'set-A-num!
+ (f ((core-get B-ptr) 'A-num) ((core-get A-ptr) 'B-num)) name)
+ ((core-get B-ptr) 'set-B-num!
+ (f ((core-get B-ptr) 'B-num) ((core-get A-ptr) 'A-num)) name))))
+
+(define (eval-operand mode num ptr)
+ (addr+ ptr
+ (case mode
+ ((immediate) 0)
+ ((direct) num)
+ ((indirect-A) (addr+ num ((core-get (addr+ ptr num)) 'A-num)))
+ ((indirect-B) (addr+ num ((core-get (addr+ ptr num)) 'B-num)))
+ ((pre-indirect-A)
+ (let ((aux-instr (core-get (addr+ ptr num))))
+ ((aux-instr set-A-num! (addr+ -1 (aux-instr 'A-num))))
+ (addr+ num (aux-instr 'A-num))))
+ ((pre-indirect-B)
+ (let ((aux-instr (core-get (addr+ ptr num))))
+ (aux-instr set-B-num!(addr+ -1 (aux-instr 'B-num)))
+ (addr+ num (aux-instr 'B-num))))
+ ((post-indirect-A)
+ (let* ((aux-instr (core-get (addr+ ptr num)))
+ (old-A-num (aux-instr 'A-num)))
+ (aux-instr set-A-num! (addr+ 1 (aux-instr 'A-num)))
+ (addr+ num old-A-num)))
+ ((post-indirect-B)
+ (let* ((aux-instr (core-get (addr+ ptr num)))
+ (old-B-num (aux-instr 'B-num)))
+ (aux-instr set-B-num! (addr+ 1 (aux-instr 'B-num)))
+ (addr+ num old-B-num)))
+ (else
+ (error "Unrecognized mode" mode)))))
+
+;;; TEST CODE
+
+(define addressing-test
+ (make-prog 'at (list
+ (make-instr 'DAT 'F 'immediate 42 'immediate 53 'at)
+ (make-instr 'DAT 'F 'immediate 123 'immediate 256 'at)
+ (make-instr 'MOV 'A 'indirect-B 4 'direct 7 'at)
+ (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
+ (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
+ (make-instr 'NOP 'I 'immediate 0 'immediate 0 'at)
+ (make-instr 'DAT 'F 'immediate -5 'immediate -6 'at)) 2))
+
+(define imp
+ (make-prog 'imp (list (make-instr 'MOV 'I 'direct 0 'direct 1 'imp)) 0))
+
+(define dwarf
+ (make-prog 'dwarf (list
+ (make-instr 'DAT 'F 'immediate 0 'immediate -1 'dwarf)
+ (make-instr 'ADD 'AB 'immediate 5 'direct -1 'dwarf)
+ (make-instr 'MOV 'I 'direct -2 'indirect-B -2 'dwarf)
+ (make-instr 'JMP 'I 'immediate -2 'immediate 0 'dwarf)) 1))
+
+(initialize-core)
+(define players (install-progs (list dwarf imp)))
+
+(dump-core)