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