scsh-0.5/scsh/static.scm.in

#!@prefix@/lib/scsh/scshvm \
-o @prefix@/lib/scsh/scshvm -h 8000000 -i @prefix@/lib/scsh/scsh.image -lm @prefix@/lib/scsh/vm/ps-interface.scm -lm @prefix@/lib/scsh/vm/interfaces.scm -lm @prefix@/lib/scsh/vm/package-defs.scm -lm @prefix@/lib/scsh/vm/s48-package-defs.scm -dm -m static-heaps -e static-heap-linker -s 
!#

#!
For testing load this at a scsh prompt
,config ,load ../vm/ps-interface.scm
,config ,load ../vm/interfaces.scm
,config ,load ../vm/package-defs.scm
,config ,load ../vm/s48-package-defs.scm
,config ,load static.scm
,load-package static-heaps
,in static-heaps
!#

;;; Static heap package for the Scheme Shell
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Copyright (c) 1995-1996 by Brian D. Carlstrom.
;;;
;;; based on Scheme48 implementation.
;;; Copyright (c) 1993, 1994 by Richard Kelsey and Jonathan Rees.
;;;
;;; The business of this package is converting a Scheme 48 bytecode
;;; image as embodied in a .image file to a C representation. This C
;;; code is then compiled and linked in with a virtual machine. One
;;; pleasant side effect of this is reduced startup times. Another
;;; good thing is that immutable parts of the image can be shared
;;; between processes.

(define-structure static-heaps
  (export static-heap-linker)
  (open scheme heap memory data stob struct
	heap-extra
	vm-architecture
	formats
	enumerated
	signals
	tables
	defrec-package
	scsh)
  (begin
    
;;; static-heap-linker
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; the external entry point
;;; real work in static-heap-linker1
;;; argl is a list of the command line arguments
    (define (static-heap-linker argl)
      (cond ((not (= (length argl) 3))
	     (format #t 
		     "usage: ~a input-image-file output-executible-file" 
		     (car argl))
	     (exit 1)))
      (let ((temp-dir			; place for intermediate .c .o files
	     (or (getenv "TMPDIR") 
		 "@TMPDIR@"))
	    (cc-command			; command to compile a .c file
	     (or (getenv "CC")
		 "@CC@ @CFLAGS@"))
	    (ld-flags			; flags needed to link executible
	     (or (getenv "LDFLAGS")
		 "@LDFLAGS@"))
	    (libraries			; linbraries need to link executible
	     (or (getenv "LIBS")
		 "@LIBS@"))
	    (input-image		; the input scheme image file
	     (cadr argl))
	    (output-executible		; the output executible file
	     (caddr argl)))
	(static-heap-linker1 input-image temp-dir output-executible
			     cc-command ld-flags libraries)
	(exit 0)))

;;; heap structure
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

    (define-record heap
      (length    0)
      (objects '())
      )

;;; static-heap-linker1
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    (define (static-heap-linker1 input-image tempdir output-executible
				 cc-command ld-flags libraries)
      (let* ((temp-dir			; make a unique directory with pid
	      (format #f "~a/scsh~s" tempdir (pid)))
	     (output-file		; executible relateive to cwd
	      (string-append (cwd) "/" output-executible))
	     (start			; entry point of image
	      (read-heap-image input-image))) ; *** READ ***
	(receive (pure impure reloc externs)
	    (create-heaps-and-tables)	      ; *** EVAL ***
	  ;;; if directory exists blow it away
	  ;;; useful for repeated runs from within same scsh process
	  (if (file-exists? temp-dir)
	      (if (file-directory? temp-dir)
		  (with-cwd temp-dir
			    (map delete-file (directory-files temp-dir #t)))
		  (delete-file temp-dir)))
	  (create-directory temp-dir #o755 #t)
	  (with-cwd temp-dir		      ; *** PRINT ***
		    (write-c-header-file pure impure externs)
		    (write-c-image pure impure reloc externs)
		    (write-main-c-file start reloc)
		    (compile-c-files cc-command)
		    (link-files cc-command ld-flags libraries 
				output-file)
		    (map delete-file (directory-files temp-dir #t)))
	  (delete-directory temp-dir))))

;;; read-heap-image
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; reads the scheme48 bytecode image into memory.
;;; returns entry point.
    (define (read-heap-image infile)
      (let ((bytes (file-info:size (file-info infile))))
	(init (inexact->exact (floor (* 1.1 bytes))) infile)))
    ; XXX need little extra space for find-all-xs

;;; create-heaps-and-tables
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Walks over the in memory scheme 48 heap image. 
;;; Returns
;;;   1.) vector of heaps describing   pure heap objects
;;;   2.) vector of heaps describing impure heap objects
;;;   3.) vector of tables descibing relocations
;;;   4.) table of external references
    (define (create-heaps-and-tables)
      (let* ((n       (nchunks))	; number of chunks we have in image
	     (  pure  (make-vector n))	; immutable bits of each chunk
	     (impure  (make-vector n))	;   mutable bits of each chunk
	     (reloc   (make-vector n))	; relocation information
	     (externs (make-table)))	; external references
	;; create empty heaps for each chunk
	(let loop ((i 0))
	  (cond ((not (= i n))
		 (vector-set!   pure i (make-heap))
		 (vector-set! impure i (make-heap))
		 (vector-set!  reloc i (make-table))
		 (loop (+ i 1)))))
	;; here is where we iterate through all the bits
	;; we construct our own data structures describing the layout
	(scsh-for-each-stored-object
	 (lambda (chunk)
	   (format #t "Reading chunk number ~s" chunk))
	 (lambda (chunk x len)
	   (let* ((heap			; choose the appropriate heap
		   (vector-ref (if (mutable? x) impure pure) chunk)))
	     ;; add the relocation information
	     (table-set! (vector-ref reloc chunk) x (heap:length heap))
	     ;; add object reference to heap chunk
	     (set-heap:objects heap (cons x (heap:objects heap)))
	     ;; update current heap chunk length
	     (set-heap:length  heap (+ len  (heap:length  heap)))
	     ;; if we have an external reference handle add it to the list
	     (if (= (header-type (stob-header x)) (enum stob external))
		 (table-set! externs 
			     (external-value x) 
			     (vm-string->string (external-name x))))))
	 (lambda (chunk) 
	   (newline)))
	;; put all the heaps in the correct order
	(let loop ((i 0))
	  (cond ((not (= i n))
		 (let ((p (vector-ref   pure i))
		       (i (vector-ref impure i)))
		   (set-heap:objects p (reverse (heap:objects p)))
		   (set-heap:objects i (reverse (heap:objects i))))
		 (loop (+ i 1)))))
	(values pure impure reloc externs)))

;;; vm-string->string
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; converts a vm-string to a scheme one that we can handle
    (define (vm-string->string x)
      (cond ((vm-string? x)
	     (let ((len (vm-string-length x)))
	       (let loop ((i 0) 
			  (l '()))
		 (cond ((= i len) 
			(list->string (reverse l)))
		       (else
			(loop (+ i 1) (cons (vm-string-ref x i) l)))))))
	    (else
	     (message x " is not a vm-string"))))

;;; write-c-header-file
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; declares the c long arrays for each heap chunk 
;;; declares the extern references to other c functions
    (define (write-c-header-file pure impure externs)
      (message "Writing header file")
      (call-with-output-file "static.h"
	(lambda (port)
	  (format port "/* Static Heap File Automatically Generated~%")
	  (format port " * by scsh/static.scm */~%")
	  ;; declare the long arrays for each heap chunk
	  (let ((n (nchunks)))
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "extern const long p~s[~s];~%" i 
		      (quotient (heap:length (vector-ref   pure i)) 4)))
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "extern long i~s[~s];~%" i
		      (quotient (heap:length (vector-ref impure i)) 4))))
	  ;; declare the external references
	  (table-walk
	   (lambda (address name)
	     (format port "const extern ~a();~%" name))
	   externs)
	  )))

;;; write-c-image
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; responsible for writing the pure and impure heaps
    (define (write-c-image pure impure reloc externs)
      (message "Writing   pure c files")
      (write-c-image1   pure "p" "const " reloc externs)
      (message "Writing impure c files")
      (write-c-image1 impure "i" ""       reloc externs))

;;; write-c-image1
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; writes the c long array
    (define (write-c-image1 heap name const reloc externs)
      (let ((n (nchunks)))
	;; iterate over all the chunks for this part of heap
	(let chunk-loop ((c 0))
	  (cond ((not (= c n))
		 (format #t "Writing static-~a~s.c~%" name c)
		 (call-with-output-file 
		     (format #f "static-~a~s.c" name c)
		   (lambda (port)	     
		     (format port "#include \"static.h\"~%")
		     (format port "~a long ~a~s[]={~%" const name c)
		     (let ((heap (vector-ref heap c)))
		       ;; iterate over each object
		       (let heap-loop ((l (heap:objects heap)))
			 (cond ((not (null? l))
				(scsh-emit-initializer 
				 (car l) reloc externs port)
				(heap-loop (cdr l))))))
		     (display "};" port)
		     (newline port)))
		 (chunk-loop (+ 1 c)))))))

;;; write-main-c-file
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; creates the top level interfaces that scheme48 wants to see
;;;  p_count i_count
;;;    number of chunks
;;;  p_areas i_areas
;;;    pointers to each chunk
;;;  p_sizes i_sizes
;;;    sizes of each chunk
;;; entry
;;;    the starting entry point
    (define (write-main-c-file start reloc)
      (let ((n (nchunks)))
	(call-with-output-file "static.c"
	  (lambda (port)
	    (format port "#include \"static.h\"~%")
	    (format port "const long p_count = ~s;~%" n)
	    (format port "const long i_count = ~s;~%" n)
	    
	    (format port "const long * const p_areas[~s] = {" n)
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "(const long *) &p~s, " i))
	    (format port "};~%")
	    (format port "long * const i_areas[~s] = {" n)
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "(long *) &i~s, " i))
	    (format port "};~%")

	    (format port "const long p_sizes[~s] = {" n)
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "sizeof(p~s), " i))
	    (format port "};~%")
	    (format port "const long i_sizes[~s] = {" n)
	    (do ((i 0 (+ i 1)))
		((= i n))
	      (format port "sizeof(i~s), " i))
	    (format port "};~%")

	    (display "const long entry = " port)
	    (scsh-emit-descriptor start reloc port)
	    (write-char #\; port)
	    (newline port)))))

;;; compile-c-files 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; compiles the chunk .c files as well as the main .c file
    (define (compile-c-files cc-command)
      (let ((n (nchunks))
	    (cc (append (line->list cc-command) '(-c))))
	(message "Compiling main C file")
	(message (append cc '("static.c")))
	(run (,@(append cc  '("static.c"))))
	(do ((i 0 (+ i 1)))
	    ((= i n))
	  (message "Compiling C file for   pure chunk " i)
	  (message (append cc (list (format #f "static-p~s.c" i))))
	  (run (,@(append cc 
			  (list (format #f "static-p~s.c" i)))))
	  (message "Compiling C file for impure chunk " i)
	  (message (append cc (list (format #f "static-i~s.c" i))))
	  (run (,@(append cc 
			  (list (format #f "static-i~s.c" i))))))))
;;; link-files
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; links the .o's from compile-c-files
;;; uses the provided flags and libraries
;;; produces outfile as executible
    (define (link-files cc-command linker-flags libraries outfile)
      (let ((n (nchunks))
	    (ld (append (line->list cc-command)
			(line->list linker-flags)
			`(-o ,outfile)))
	    (libs (line->list libraries)))
	(message "Linking executible")
	(message (append ld
			 (let loop ((i 0)
				    (l '()))
			   (cond ((not (= i n))
				  (loop (+ i 1)
					(cons 
					 (format #f "static-i~s.o" i)
					  (cons
					   (format #f "static-p~s.o" i)
					   l))))
				 (else 
				  (reverse 		
				   (cons "static.o"
					 l)))))
			 '("@prefix@/lib/scsh/libscshvm.a")
			 libs))
	(run (,@(append 
		 ld
		 (let loop ((i 0)
			    (l '()))
		   (cond ((not (= i n))
			  (loop (+ i 1)
				 (cons 
				  (format #f "static-i~s.o" i)
				  (cons
				   (format #f "static-p~s.o" i)
				   l))))
			  (else 
			   (reverse 		
			    (cons "static.o"
				  l)))))
		 '("@prefix@/lib/scsh/libscshvm.a")
		 libs)))))

;;; scsh-emit-initializer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; see scheme48 emit-initialize below
    (define (scsh-emit-initializer x reloc externs port)
      ;; emit the header
      (write-hex port (stob-header x))
      ;; handle descriptor vectors and vm-strings. 
      ;; everything else is a byte vector
      (cond ((d-vector? x)
	     (scsh-emit-d-vector-initializer x reloc port))
	    ((vm-string? x)
	     (scsh-emit-vm-string-initializer x port))
	    (else
	     (scsh-emit-b-vector-initializer x externs port)))
      (if *comments?*
	  (begin (display " /* " port)
		 (writex x port)
		 (display " */" port)))
      (newline port))

;;; scsh-emit-d-vector
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; descriptor vectors are pretty easy given scsh-emit-descriptor
    (define (scsh-emit-d-vector-initializer x reloc port)
      (let ((len (d-vector-length x)))
	(do ((i 0 (+ i 1)))
	    ((= i len))
	  (scsh-emit-descriptor (d-vector-ref x i) reloc port)
	  (write-char #\, port))))

;;; scsh-emit-descriptor
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; for descrriptors we consult the relocation table
    (define (scsh-emit-descriptor x reloc port)
      (if (stob? x)
	  (let ((n (chunk-number x)))
	    (display "(long)(&" port)
	    (if (immutable? x)
		(display "p" port)
		(display "i" port))
	    (display n port)
	    (display "[" port)
	    (display (quotient (table-ref (vector-ref reloc n) x) 4) port)
	    (display "])+7" port))
	  (format port 
		  (if (negative? x) "-0x~a" "0x~a")
		  (number->string (abs x) 16))))

;;; scsh-emit-vm-string-initializer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; vm-strings are converted to numbers and byte order adjusted
    (define (scsh-emit-vm-string-initializer x port)
      (let* ((len (vm-string-length x))	; end is jawilson style hack
	     (end (- (cells->bytes (bytes->cells (+ len 1))) 4)))
	(do ((i 0 (+ i 4)))
	    ((= i end) 
	     (case (- len end)
	       ((0)
		(write-hex port 0))
	       ((1)
		(write-hex
		 port
		 (net-to-host-32 (arithmetic-shift 
				  (char->ascii (vm-string-ref x i)) 24))))
	       ((2)
		(write-hex 
		 port
		 (net-to-host-32 
		  (bitwise-ior
		   (arithmetic-shift
		    (char->ascii (vm-string-ref x i))       24)
		   (arithmetic-shift
		    (char->ascii (vm-string-ref x (+ i 1))) 16)))))
	       ((3)
		(write-hex
		 port
		 (net-to-host-32
		  (bitwise-ior
		   (bitwise-ior
		    (arithmetic-shift 
		     (char->ascii (vm-string-ref x i))       24)
		    (arithmetic-shift 
		     (char->ascii (vm-string-ref x (+ i 1))) 16))
		   (arithmetic-shift  
		    (char->ascii (vm-string-ref x (+ i 2)))  8)))))))
	  (write-hex port
		     (net-to-host-32 (bitwise-ior
				      (bitwise-ior
				       (arithmetic-shift 
					(char->ascii 
					 (vm-string-ref x i))       24)
				       (arithmetic-shift 
					(char->ascii 
					 (vm-string-ref x (+ i 1))) 16))
				      (bitwise-ior
				       (arithmetic-shift 
					(char->ascii 
					 (vm-string-ref x (+ i 2)))  8)
				       (char->ascii  
					(vm-string-ref x (+ i 3))))))
		     ))))

;;; scsh-emit-b-vector-initializer
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; byte vectors are byte order adjusted too
    (define (scsh-emit-b-vector-initializer x externs port)
      (cond ((and (code-vector? x)
		  (table-ref externs x)) =>
		  (lambda (name)
		    (format port "(long) *~a," name)))
	    (else 
	     (let* ((len (b-vector-length x)) ;end is jawilson style hack
		    (end (- (cells->bytes (bytes->cells (+ len 1))) 4)))
	       (do ((i 0 (+ i 4)))
		   ((= i end)
		    (case (- len end)
		      ((1)
		       (write-hex
			port
			(net-to-host-32 
			 (arithmetic-shift (b-vector-ref x i) 24))))
		      ((2)
		       (write-hex 
			port
			(net-to-host-32
			 (bitwise-ior
			  (arithmetic-shift (b-vector-ref x i)       24)
			  (arithmetic-shift (b-vector-ref x (+ i 1)) 16)))))
		      ((3)
		       (write-hex
			port
			(net-to-host-32
			 (bitwise-ior
			  (bitwise-ior
			   (arithmetic-shift (b-vector-ref x i)       24)
			   (arithmetic-shift (b-vector-ref x (+ i 1)) 16))
			  (arithmetic-shift  (b-vector-ref x (+ i 2))  8)))
			))))
		 (write-hex 
		  port
		  (net-to-host-32 (bitwise-ior
				   (bitwise-ior
				    (arithmetic-shift 
				     (b-vector-ref x i)       24)
				    (arithmetic-shift 
				     (b-vector-ref x (+ i 1)) 16))
				   (bitwise-ior
				    (arithmetic-shift 
				     (b-vector-ref x (+ i 2))  8)
				    (b-vector-ref x (+ i 3))))))))
	     )))

;;; scsh-for-each-stored-object
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; see scheme48 for-each-stored-object
;;; Image traversal utility

    (define (scsh-for-each-stored-object chunk-start proc chunk-end)
      (let ((limit (heap-pointer)))
	(let chunk-loop ((addr (newspace-begin))
			 (i 0)
			 (chunk (+ (newspace-begin) *chunk-size*)))
	  (if (addr< addr limit)
	      (begin (chunk-start i)
		     (let loop ((addr addr))
		       (if (and (addr< addr limit)
				(addr< addr chunk))
			   (let* ((d   (fetch addr))
				  (len (addr1+ (header-a-units d))))
			     (if (not (header? d))
				 (warn "heap is in an inconsistent state" d))
			     (proc i 
				   (address->stob-descriptor (addr1+ addr)) 
				   len)
			     (loop (addr+ addr len)))
			   (begin (chunk-end i)
				  (chunk-loop addr
					      (+ i 1)
					      (+ chunk *chunk-size*))))))))))
;;; write-hex
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; utility routine to print a scheme number as a c hex number
    (define (write-hex port x) 
      (format port 
	      (if (negative? x) "-0x~a," "0x~a,")
	      (number->string (abs x) 16)))

;;; line->list
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; utility that takes a string and break it into a list at whitespace
;;; rewrite using scsh stuff?
    (define (line->list line)
      (let ((len (string-length line)))
	(let loop ((start 0)
		   (end 0)
		   (l '()))
	  (cond ((>= end len)
		 (if (= start end)
		     l
		     (append l (list (substring line start end)))))
		((and (= start end)
		      (or (char=? (string-ref line start) (ascii->char 32))
			  (char=? (string-ref line start) (ascii->char 9))))
		 (loop (+ 1 start) 
		       (+ 1 end) 
		       l))
		((or (char=? (string-ref line end) (ascii->char 32))
		     (char=? (string-ref line end) (ascii->char 9)))
		 (loop (+ 1 end) 
		       (+ 1 end) 
		       (append l (list (substring line start end)))))
		((< end len)
		 (loop start 
		       (+ 1 end)
		       l))
		(else (error "unexpected case in line->list"))))))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Debugging
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

    (define (bin n)
      (number->string n 2))

    (define (oct n)
      (number->string n 8))

    (define (dec n)
      (number->string n 10))

    (define (hex n)
      (number->string n 16))
    
    ;;; Static Heap Code From Scheme48
    ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    ;;; The Scheme 48 version produced monolithic C files that even
    ;;; the GNU C Compiler couldn't handle, let alone standard vendor
    ;;; compilers...
    ;;; It also relied upon the C compiler to fill in some pointer
    ;;; information. Because I needed to break up the files, I had to
    ;;; calculate this information myself.

    ; For example:
    ;   (do-it 100000 "~/s48/debug/little.image" "little-heap.c")
    ;
    ; The first argument to do-it should be somewhat larger than the size,
    ; in bytes, of the image file to be converted (which you can obtain with
    ; "ls -l").
    ;
    ; If the image contains 0-length stored objects, then the .c file will
    ; have to be compiled by gcc, since 0-length arrays aren't allowed in
    ; ANSI C.  This wouldn't be difficult to work around.
    
    (define *comments?* #f)
    
    ; 800,000 bytes => 200,000 words => at least 100,000 objects
    ;   50 chunks => 16,000 bytes per chunk => 2,000 objects per chunk
    (define *chunk-size* 10000)

    (define (do-it bytes infile outfile)
      (let ((start (init bytes infile)))
	(call-with-output-file outfile
	  (lambda (port)
	    (format port "#define D(x) (long)(&x)+7~%")
	    (format port "#define H unsigned long~%")
	    (emit-area-declarations "p" immutable? "const " port)
	    (emit-area-declarations "i" mutable? "" port)
	    (emit-area-initializers "p" immutable? "const " port)
	    (emit-area-initializers "i" mutable? "" port)
	    (display "const long entry = " port)
	    (emit-descriptor start port)
	    (write-char #\; port)
	    (newline port)))))

    (define (init bytes infile)
      (create-memory (quotient bytes 2) quiescent) ;Output of ls -l
      (initialize-heap (memory-begin) (memory-size))
      (let ((start (read-image infile 0)))
	(message (nchunks)
		 " chunks")
	start))

    (define (nchunks) (+ (chunk-number (heap-pointer)) 1))

					; emit struct declarations for areas

    (define (emit-area-declarations name in-area? const port)
      (for-each-stored-object
       (lambda (chunk)
	 (message name chunk " declaration")
	 (display "struct " port) (display name port) (display chunk port)
	 (display " {" port) (newline port))
       (lambda (x)
	 (if (in-area? x)
	     (emit-declaration x port)))
       (lambda (chunk)
	 (display "};" port)
	 (newline port)
	 (display const port)
	 (display "extern struct " port) (display name port) (display chunk port)
	 (write-char #\space port) (display name port) (display chunk port)
	 (write-char #\; port) (newline port)
	 chunk)))

    (define (emit-declaration x port)
      (display "  H x" port)
      (writex x port)
      (cond ((d-vector? x)
	     (display "; long d" port)
	     (writex x port)
	     (write-char #\[ port)
	     (write (d-vector-length x) port))
	    ((vm-string? x)
	     (display "; char d" port)
	     (writex x port)
	     (write-char #\[ port)
	     ;; Ensure alignment (thanks Ian)
	     (write (cells->bytes (bytes->cells (b-vector-length x)))
		    port))
	    (else
	     (display "; unsigned char d" port)
	     (writex x port)
	     (write-char #\[ port)
	     ;; Ensure alignment
	     (write (cells->bytes (bytes->cells (b-vector-length x)))
		    port)))
      (display "];" port)
      (if *comments?*
	  (begin (display " /* " port)
		 (display (enumerand->name (stob-type x) stob) port)
		 (display " */" port)))
      (newline port))

					; Emit initializers for areas

    (define (emit-area-initializers name in-area? const port)
      (for-each-stored-object
       (lambda (chunk)
	 (message name chunk " initializer")

	 (display const port)
	 (display "struct " port) (display name port) (write chunk port)
	 (write-char #\space port) (display name port) (write chunk port)
	 (display " =" port) (newline port)

	 (write-char #\{ port) (newline port))
       (lambda (x)
	 (if (in-area? x)
	     (emit-initializer x port)))
       (lambda (chunk)
	 (display "};" port) (newline port)))

      (let ((n (nchunks)))
	(format port "const long ~a_count = ~s;~%" name n)
	(format port "~a long * const ~a_areas[~s] = {" const name n)
	(do ((i 0 (+ i 1)))
	    ((= i n))
	  (format port "(~a long *)&~a~s, " const name i))
	(format port "};~%const long ~a_sizes[~s] = {" name n)
	(do ((i 0 (+ i 1)))
	    ((= i n))
	  (format port "sizeof(~a~s), " name i))
	(format port "};~%")))


    (define (message . stuff)
      (for-each display stuff) (newline))

    (define (emit-initializer x port)
      (display "  " port)
      (write (stob-header x) port)
      (write-char #\, port)
      (cond ((d-vector? x)
	     (emit-d-vector-initializer x port))
	    ((vm-string? x)
	     (write-char #\" port)
	     (let ((len (vm-string-length x)))
	       (do ((i 0 (+ i 1)))
		   ((= i len) (write-char #\" port))
		 (let ((c (vm-string-ref x i)))
		   (cond ((or (char=? c #\") (char=? c #\\))
			  (write-char #\\ port))
			 ((char=? c #\newline)
			  (display "\\n\\" port)))
		   (write-char c port)))))
	    (else
	     (write-char #\{ port)
	     (let ((len (b-vector-length x)))
	       (do ((i 0 (+ i 1)))
		   ((= i len) (write-char #\} port))
		 (write (b-vector-ref x i) port)
		 (write-char #\, port)))))
      (write-char #\, port)
      (if *comments?*
	  (begin (display " /* " port)
		 (writex x port)
		 (display " */" port)))
      (newline port))

    (define (emit-d-vector-initializer x port)
      (write-char #\{ port)
      (let ((len (d-vector-length x)))
	(do ((i 0 (+ i 1)))
	    ((= i len) (write-char #\} port))
	  (emit-descriptor (d-vector-ref x i) port)
	  (write-char #\, port))))

    (define (emit-descriptor x port)
      (if (stob? x)
	  (begin (if (immutable? x)
		     (display "D(p" port)
		     (display "D(i" port))
		 (display (chunk-number x) port)
		 (display ".x" port)
		 (writex x port)
		 (write-char #\) port))
	  (write x port)))


					; Foo

    (define (writex x port)
      (write (quotient (- (- x (memory-begin)) 7) 4) port))

    (define (chunk-number x)
      (quotient (- (- x (memory-begin)) 7) *chunk-size*))


					; Image traversal utility

    (define (for-each-stored-object chunk-start proc chunk-end)
      (let ((limit (heap-pointer)))
	(let chunk-loop ((addr (newspace-begin))
			 (i 0)
			 (chunk (+ (newspace-begin) *chunk-size*)))
	  (if (addr< addr limit)
	      (begin (chunk-start i)
		     (let loop ((addr addr))
		       (if (and (addr< addr limit)
				(addr< addr chunk))
			   (let ((d (fetch addr)))
			     (if (not (header? d))
				 (warn "heap is in an inconsistent state" d))
			     (proc (address->stob-descriptor (addr1+ addr)))
			     (loop (addr1+ (addr+ addr (header-a-units d)))))
			   (begin (chunk-end i)
				  (chunk-loop addr
					      (+ i 1)
					      (+ chunk *chunk-size*))))))))))

    (define (mutable? x) (not (immutable? x)))

    ;; End begin
    ))