collapseos/forth/blk.fs

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( 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+ ;
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: BLK( 6 BLKMEM+ ;
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: BLK$
H@ 0x57 RAM+ !
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( 1024 for the block, 6 for variables )
1030 ALLOT
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( LOAD detects end of block with ASCII EOT. This is why
we write it there. EOT == 0x04 )
4 C,
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-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
;
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: _
(boot<)
DUP 4 = IF
DROP
( We're finished interpreting )
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EXIT!
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THEN
;
: LOAD
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( save BLK>, CINPTR and boot< ptr to RSP )
BLK> @ >R
0x0c RAM+ @ >R
0x2e RAM+ @ >R
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BLK@
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( Point to beginning of BLK )
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BLK( 0x2e RAM+ !
( 0c == CINPTR )
['] _ 0x0c RAM+ !
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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
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;