Single linked list unit

darktemplar (Piotr) — Sun, 07 Jan 2007 17:58:21 GMT

This code is a simple pascal library to handle single-linked-lists

function llsGetItem(id: cardinal; var start: pointer): pointer;

Returns an item of specified ID, it remains in list

function llsTakeOutItem(id: cardinal; var start: pointer): pointer;

Returns an item of specified ID, it is removed from list

procedure llsInsertItem(item: pointer; var start: pointer);

Inserts an item to list(item is a valid header)

function llsGetItemCount(start: pointer): cardinal;

Gets number of items

function llsNewSLLHeader: PSLLItem;

Allocates list item header

procedure llsKillSLLHeader(hdr: pointer);

Deallocated list item header



unit SLLMan;

interface

type

  PSLLItem = ^TSLLItem;

  TSLLItem = record

    Next: pointer;

    Data: pointer;

   end;



function llsGetItem(id: cardinal; var start: pointer): pointer;

function llsTakeOutItem(id: cardinal; var start: pointer): pointer;

procedure llsInsertItem(item: pointer; var start: pointer);

function llsGetItemCount(start: pointer): cardinal;

function llsNewSLLHeader: PSLLItem;

procedure llsKillSLLHeader(hdr: pointer);

       // These ids are numbered from 0

implementation

function malloc(size: cardinal): pointer;

begin

  GetMem(result,size);

end;

function llsGetItemCount(start: pointer): cardinal;

var

  cur: PSLLItem;

  tmp: cardinal;

begin

  if start = nil then begin llsGetItemCount := 0; Exit; end;

  tmp := 1;  cur := start;

  while (cur^.Next <> nil) do

  begin

    Inc(tmp);

    cur := cur^.Next;

  end;

  llsGetItemCount := tmp;

end;

procedure llsKillSLLHeader(hdr: pointer);

begin

  if hdr = nil then Exit;

  Free(hdr);

end;

function llsNewSLLHeader: PSLLItem;

var

  tmp: PSLLItem;

begin

  tmp := malloc(sizeof(TSLLItem));

  tmp^.Next := nil;

  tmp^.Data := nil;

  llsNewSLLHeader := tmp;

end;

function llsGetItem(id: cardinal; var start: pointer): pointer;

var

  cur: PSLLItem;

begin

  if start = nil then begin llsGetItem := nil; Exit; end;

  cur := start;

  while (id<>0) do

  begin

    if cur^.Next <> nil then

        begin

          Dec(id);

          cur := cur^.Next;

        end else

        begin

          llsGetItem := nil;

          Exit;

        end;

  end;

  llsGetItem := cur;

end;



function llsTakeOutItem(id: cardinal; var start: pointer): pointer;

var

  tmp: PSLLItem;

  last: PSLLItem;

begin

  if start = nil then begin llsTakeOutItem := nil; Exit; end;

  if (id = 0) then

    begin

      tmp := start;

      if tmp^.Next = nil then start := nil else start := tmp^.Next;

      llsTakeOutItem := tmp;

      Exit;

    end;

  tmp := start;

  repeat

    dec(id);

    last := tmp;

    tmp := tmp^.Next;

  until (id = 0);

  last^.Next := tmp^.Next;

  llsTakeOutitem := tmp;

end;

procedure llsInsertItem(item: pointer; var start: pointer);

var

  cur: PSLLItem;

begin

 if start = nil then

  begin

    start := item;

    exit;

  end;

 cur := start;

 while (cur^.Next<>nil) do cur := cur^.Next;

 cur^.Next := item;

end;



end.

Converting diskette LBA to CHS

darktemplar (Piotr) — Tue, 12 Dec 2006 02:05:46 GMT

// description of your code here

Put LBA address in AX and get your results in CL, CH and DH.



;-----------------------------------------------------------------------------;

;		DISKETTE_LBA_TO_CHS(AX LBA) CL Head, CH Cylinder, DH Sector   ;

;-----------------------------------------------------------------------------;

diskette_lba_to_chs:

	xor dx, dx

	mov bx, 18

        div bx

	push dx				; = Stack(1)			

	mov dx, ax

        shr ax, 2

	mov cl, al

	mov ch, dl

	pop dx				; = Stack(0)

	inc dl

	mov dh, dl

	ret

[ASM]Write String only using BIOS

darktemplar (Piotr) — Tue, 12 Dec 2006 02:02:47 GMT

First, set starting address of text into DS:SI registers. Procedure writes text until null-character is met.



;-----------------------------------------------------------------------------;

;		WRITE_STRING(DS:SI Text)                                      ;

;-----------------------------------------------------------------------------;

;	Writes string from DS:SI until character #0 is met		      ;

Write_String:		

	mov ah, 0xE	

	xor bh, bh	

	mov bl, 0x7

.nextchar	

	lodsb		

	or al,al

	jz .return

	int 10h	

	jmp .nextchar

.return		

	ret

DZone Snippets: Darktemplar's Code Snippets

Single linked list unit

Converting diskette LBA to CHS

[ASM]Write String only using BIOS