freebsd/sys/boot/ficl/softwords/classes.fr

\ ** ficl/softwords/classes.fr
\ ** F I C L   2 . 0   C L A S S E S
\ john sadler  1 sep 98
\ Needs oop.fr

.( loading ficl utility classes ) cr
also oop definitions

\ REF subclass holds a pointer to an object. It's
\ mainly for aggregation to help in making data structures.
\
object subclass c-ref
    cell: .class
    cell: .instance

	: get   ( inst class -- refinst refclass )
		drop 2@ ;
	: set   ( refinst refclass inst class -- )
		drop 2! ;
end-class

object subclass c-byte
	char: .payload

	: get  drop c@ ;
	: set  drop c! ;
end-class

object subclass c-2byte
	2 chars: .payload

	: get  drop w@ ;
	: set  drop w! ;
end-class

object subclass c-4byte
	cell: .payload

	: get  drop @ ;
	: set  drop ! ;
end-class


\ ** C - P T R 
\ Base class for pointers to scalars (not objects).
\ Note: use c-ref to make references to objects. C-ptr
\ subclasses refer to untyped quantities of various sizes.

\ Derived classes must specify the size of the thing
\ they point to, and supply get and set methods.

\ All derived classes must define the @size method:
\ @size ( inst class -- addr-units )
\ Returns the size in address units of the thing the pointer
\ refers to.
object subclass c-ptr
    c-4byte obj: .addr

    \ get the value of the pointer
    : get-ptr   ( inst class -- addr )
        c-ptr   => .addr  
        c-4byte => get  
    ;

    \ set the pointer to address supplied
    : set-ptr   ( addr inst class -- )
        c-ptr   => .addr  
        c-4byte => set  
    ;

    \ increment the pointer in place
    : inc-ptr   ( inst class -- )
        2dup 2dup                   ( i c i c i c )
        c-ptr => get-ptr  -rot      ( i c addr i c )
        --> @size  +  -rot          ( addr' i c )
        c-ptr => set-ptr
    ;

    \ decrement the pointer in place
    : dec-ptr    ( inst class -- )
        2dup 2dup                   ( i c i c i c )
        c-ptr => get-ptr  -rot      ( i c addr i c )
        --> @size  -  -rot          ( addr' i c )
        c-ptr => set-ptr
    ;

    \ index the pointer in place
    : index-ptr   ( index inst class -- )
        locals| class inst index |
        inst class  c-ptr => get-ptr        ( addr )
        inst class --> @size  index *  +    ( addr' )
        inst class  c-ptr => set-ptr
    ;

end-class


\ ** C - C E L L P T R 
\ Models a pointer to cell (a 32 bit scalar). 
c-ptr subclass c-cellPtr
    : @size   2drop  4  ;
    \ fetch and store through the pointer
	: get   ( inst class -- cell )
        c-ptr => get-ptr @  
    ;
	: set   ( value inst class -- )
        c-ptr => get-ptr !  
    ;
end-class


\ ** C - 2 B Y T E P T R 
\ Models a pointer to a 16 bit scalar
c-ptr subclass c-2bytePtr
    : @size   2drop  2  ;
    \ fetch and store through the pointer
	: get   ( inst class -- value )
        c-ptr => get-ptr w@  
    ;
	: set   ( value inst class -- )
        c-ptr => get-ptr w!  
    ;
end-class


\ ** C - B Y T E P T R 
\ Models a pointer to an 8 bit scalar
c-ptr subclass c-bytePtr
    : @size   2drop  1  ;
    \ fetch and store through the pointer
	: get   ( inst class -- value )
        c-ptr => get-ptr c@  
    ;
	: set   ( value inst class -- )
        c-ptr => get-ptr c!  
    ;
end-class


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