mirror of
https://github.com/wwarthen/RomWBW.git
synced 2026-02-06 14:11:48 -06:00
e18014a8a7
- Credit and thanks to Ladislau Szilagyi. Co-Authored-By: ladislau szilagyi <87603175+laci1953@users.noreply.github.com>
122 lines
2.6 KiB
Plaintext
122 lines
2.6 KiB
Plaintext
const FCB_FLAG_ERROR := 1<<0;
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const FCB_FLAG_READ := 1<<1;
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const FCB_FLAG_WRITE := 1<<2;
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record FCB: RawFCB is
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pos: uint32;
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buflen: FCBIndexType;
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index: FCBIndexType;
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buffer: uint8[FCB_BUFFER_SIZE];
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flags: uint8;
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end record;
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@decl sub FCBRawRead(fcb: [FCB], pos: uint32, len: FCBIndexType): (amount: FCBIndexType);
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@decl sub FCBRawWrite(fcb: [FCB], pos: uint32, len: FCBIndexType);
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sub _fcb_init(fcb: [FCB]) is
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fcb.pos := 0;
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fcb.buflen := 0;
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fcb.index := 0;
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fcb.flags := 0;
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end sub;
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sub _fcb_advance(fcb: [FCB]) is
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fcb.index := fcb.index + 1;
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end sub;
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sub _fcb_fillbuffer(fcb: [FCB]): (b: uint8) is
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var bufpos := fcb.pos + (fcb.index as uint32);
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fcb.buflen := FCBRawRead(fcb, bufpos, FCB_BUFFER_SIZE);
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b := 0;
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if (fcb.flags & FCB_FLAG_ERROR) != 0 then
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return;
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end if;
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fcb.flags := FCB_FLAG_READ;
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fcb.pos := bufpos;
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fcb.index := 0;
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if fcb.buflen != 0 then
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b := fcb.buffer[0];
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_fcb_advance(fcb);
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end if;
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end sub;
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sub FCBFlush(fcb: [FCB]) is
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var bufpos := fcb.pos;
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if (fcb.flags & FCB_FLAG_WRITE) != 0 then
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FCBRawWrite(fcb, bufpos, fcb.index);
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if (fcb.flags & FCB_FLAG_ERROR) != 0 then
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return;
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end if;
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end if;
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fcb.pos := bufpos + (fcb.index as uint32);
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fcb.flags := 0;
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fcb.index := 0;
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fcb.buflen := 0;
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end sub;
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sub _fcb_flushbuffer(fcb: [FCB], b: uint8) is
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FCBFlush(fcb);
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if (fcb.flags & FCB_FLAG_ERROR) != 0 then
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return;
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end if;
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fcb.flags := FCB_FLAG_WRITE;
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fcb.buffer[0] := b;
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_fcb_advance(fcb);
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end sub;
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sub FCBGetChar(fcb: [FCB]): (b: uint8) is
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if (fcb.flags & FCB_FLAG_WRITE) != 0 then
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FCBFlush(fcb);
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end if;
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var i := fcb.index;
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if i == fcb.buflen then
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b := _fcb_fillbuffer(fcb);
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else
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b := fcb.buffer[i];
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_fcb_advance(fcb);
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end if;
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end sub;
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sub FCBPutChar(fcb: [FCB], b: uint8) is
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if (fcb.flags & FCB_FLAG_READ) != 0 then
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FCBFlush(fcb);
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end if;
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var i := fcb.index;
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if i == FCB_BUFFER_SIZE then
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_fcb_flushbuffer(fcb, b);
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else
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fcb.buffer[i] := b;
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_fcb_advance(fcb);
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end if;
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fcb.flags := fcb.flags | FCB_FLAG_WRITE;
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end sub;
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sub FCBPos(fcb: [FCB]): (pos: uint32) is
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pos := fcb.pos + (fcb.index as uint32);
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end sub;
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sub FCBError(fcb: [FCB]): (e: uint8) is
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e := 0;
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if (fcb.flags & FCB_FLAG_ERROR) != 0 then
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e := 1;
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end if;
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end sub;
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sub FCBSeek(fcb: [FCB], pos: uint32) is
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var delta := pos - fcb.pos;
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if (fcb.flags & FCB_FLAG_READ) != 0 then
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if delta < (fcb.buflen as uint32) then
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fcb.index := delta as FCBIndexType;
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return;
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end if;
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elseif (fcb.flags & FCB_FLAG_WRITE) != 0 then
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if delta <= (fcb.index as uint32) then
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fcb.index := delta as FCBIndexType;
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return;
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end if;
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end if;
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FCBFlush(fcb);
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fcb.pos := pos;
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end sub;
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