; -*- Mode: Scheme; Syntax: Scheme; -*-

; This is file arch.scm.

;;;; Architecture description

; Things that the VM and the runtime system both need to know.

; Bytecodes: for compiler and interpreter

(define-enumeration op
  (check-nargs=	      ;nargs   -- error if *nargs* not= operand
   check-nargs>=      ;nargs   -- error if *nargs* < operand
   make-env           ;nargs   -- cons an environment
   make-rest-list     ;nargs   -- cons a rest-argument list
   literal            ;index   -- value to *val*
   local	      ;back over
   set-local!	      ;back over
   global	      ;index   -- value to *val*
   set-global!	      ;index   -- new value in *val*
   make-closure	      ;index   -- environment in *env*
   push               ;        -- push *val* onto stack
   pop		      ;	       -- pop top of stack into *val*
   make-cont          ;delta   -- save state
   call		      ;nargs   -- proc in *val*, state in *cont*
   jump-if-false      ;delta   -- boolean in *val*
   jump		      ;delta
   return	      ;	       -- continuation in *cont*, value in *val*
   push-cont	      ;	       -- (for catch) push *cont* onto stack
   pop-cont	      ;	       -- (for throw) pop *cont* off stack
   spread-args	      ;nargs   -- spread argument list, push operand+length
   n-call	      ;	       -- call; pop nargs off stack
   native	      ;	       -- start running native code (?)

   ;; Scalar primitives
   eq?
   fixnum?
   + - * = <
   quotient remainder
   char?
   char=?
   char<?
   char->ascii
   ascii->char

   ;; Data manipulation
   pair? cons car cdr set-car! set-cdr!
   symbol? make-symbol symbol->string
   cell? make-cell cell-name contents set-contents! lookup
   closure? make-closure closure-env closure-template
   code-vector? make-code-vector code-vector-length
     code-vector-ref code-vector-set!
   string? make-string string-length string-ref string-set!
   vector? make-vector vector-length vector-ref vector-set!

   ;; I/O
   open-port
   close-port
   input-port?
   output-port?
   read-char
   peek-char
   write-char
   write-string

   ;; Misc
   unassigned
   halt 
   set-enabled-interrupts!
   return-from-interrupt
   suspend

   ;; Unnecessary primitives
   string=?
   string-hash
   reverse-list->string
   intern
   lookup
   ))

; Exception types: for exception generators and handlers.
;  - How fine should the granularity be?

(define-enumeration exception
  (unassigned-local
   undefined-global      ;cell in *val* is unbound or unassigned
   unbound-global        ;cell in *val* is unbound (for set!)
   bad-procedure
   wrong-number-of-arguments
   wrong-type-argument
   arithmetic-overflow
   index-out-of-range    ;bad index to vector-ref or string-ref
   heap-overflow	 ;(make-vector huge)
   cannot-open
   operation-on-closed-port
   uuo			 ;unimplemented instruction
   ))

; Interrupts

(define-enumeration interrupt
  (none
   keyboard  ;alarmclock, ...
   ))