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@@ -1,101 +0,0 @@
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-Program sel_des;
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-
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-uses crt,
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- go32;
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-
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-const maxx = 80;
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- maxy = 25;
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- bytespercell = 2;
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- screensize = maxx * maxy * bytespercell;
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-
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- linB8000 = $B800 * 16;
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-
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-type string80 = string[80];
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-
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-var
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- text_save : array[0..screensize-1] of byte;
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- text_oldx, text_oldy : Word;
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-
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- text_sel : Word;
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-
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-procedure status(s : string80);
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-begin
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- gotoxy(1, 1);
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- clreol;
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- write(s);
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- readkey;
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-end;
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-
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-procedure selinfo(sel : Word);
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-begin
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-gotoxy(1, 24);
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-clreol;
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-writeln('Descriptor base address : $',
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- hexstr(get_segment_base_address(sel), 8));
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-clreol;
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-write('Descriptor limit : ',
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- get_segment_limit(sel));
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-end;
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-
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-function makechar(ch : char; color : byte) : Word;
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-begin
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- result := byte(ch) or (color shl 8);
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-end;
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-
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-begin
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-seg_move(dosmemselector, linB8000,
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- get_ds, longint(@text_save), screensize);
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-text_oldx := wherex; text_oldy := wherey;
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-seg_fillword(dosmemselector, linB8000,
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- screensize div 2,
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- makechar(' ', Black or (Black shl 4)));
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-status('Creating selector ' +
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- '''text_sel'' to a part of text screen memory');
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-text_sel := allocate_ldt_descriptors(1);
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-set_segment_base_address(text_sel, linB8000
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- + bytespercell * maxx * 1);
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-set_segment_limit(text_sel,
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- screensize-1-bytespercell*maxx*3);
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-selinfo(text_sel);
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-
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-status('and clearing entire memory ' +
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- 'selected by ''text_sel'' descriptor');
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-seg_fillword(text_sel, 0,
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- (get_segment_limit(text_sel)+1) div 2,
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- makechar(' ', LightBlue shl 4));
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-
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-status('Notice that only the memory described'+
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- ' by the descriptor changed, nothing else');
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-
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-status('Now reducing it''s limit and base and '+
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- 'setting it''s described memory');
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-set_segment_base_address(text_sel,
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- get_segment_base_address(text_sel)
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- + bytespercell * maxx);
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-set_segment_limit(text_sel,
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- get_segment_limit(text_sel)
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- - bytespercell * maxx * 2);
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-selinfo(text_sel);
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-status('Notice that the base addr increased by '+
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- 'one line but the limit decreased by 2 lines');
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-status('This should give you the hint that the '+
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- 'limit is relative to the base');
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-seg_fillword(text_sel, 0,
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- (get_segment_limit(text_sel)+1) div 2,
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- makechar(#176, LightMagenta or Brown shl 4));
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-
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-status('Now let''s get crazy and copy 10 lines'+
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- ' of data from the previously saved screen');
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-seg_move(get_ds, longint(@text_save),
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- text_sel, maxx * bytespercell * 2,
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- maxx * bytespercell * 10);
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-
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-status('At last freeing the descriptor and '+
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- 'restoring the old screen contents..');
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-status('I hope this little program may give '+
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- 'you some hints on working with descriptors');
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-free_ldt_descriptor(text_sel);
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-seg_move(get_ds, longint(@text_save),
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- dosmemselector, linB8000, screensize);
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-gotoxy(text_oldx, text_oldy);
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-end.
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michael