collapseos/forth/blk.fs
2020-04-14 21:04:07 -04:00

73 lines
1.4 KiB
Forth

( I/O blocks )
: BLKMEM+ 0x57 RAM+ @ + ;
( n -- Fetches block n and write it to BLK( )
: BLK@* 0 BLKMEM+ ;
( n -- Write back BLK( to storage at block n )
: BLK!* 2 BLKMEM+ ;
( Current blk pointer in ( )
: BLK> 4 BLKMEM+ ;
: BLK( 6 BLKMEM+ ;
: BLK$
H@ 0x57 RAM+ !
( 1024 for the block, 6 for variables )
1030 ALLOT
( LOAD detects end of block with ASCII EOT. This is why
we write it there. EOT == 0x04 )
4 C,
-1 BLK> !
;
: BLK@
DUP BLK> = IF DROP EXIT THEN
DUP BLK> ! BLK@* @ EXECUTE
;
: .2 DUP 10 < IF SPC THEN . ;
: LIST
BLK@
16 0 DO
I 1 + .2 SPC
64 I * BLK( + (print)
CRLF
LOOP
;
: _
(boot<)
DUP 4 = IF
DROP
( We're finished interpreting )
EXIT!
THEN
;
: LOAD
( save BLK>, CINPTR and boot< ptr to RSP )
BLK> @ >R
0x0c RAM+ @ >R
0x2e RAM+ @ >R
BLK@
( Point to beginning of BLK )
BLK( 0x2e RAM+ !
( 0c == CINPTR )
['] _ 0x0c RAM+ !
INTERPRET
R> 0x2e RAM+ !
( Before we restore CINPTR, are we restoring it to "_"?
if yes, it means we're in a nested LOAD which means we
should also load back the saved BLK>. Otherwise, we can
ignore the BLK> from RSP. )
I 0x0c RAM+ @ = IF
( nested load )
R> DROP ( CINPTR )
R> BLK@
ELSE
( not nested )
R> 0x0c RAM+ !
R> DROP ( BLK> )
THEN
;