[Coco] Question on MINTED internals
Neal Crook
foofoobedoo at gmail.com
Wed Dec 23 18:32:07 EST 2015
Here's my contribution towards raising the technical tone of the
conversation...
I am working on a port of Luis Antoniosi's MINTED editor to produce a
version that uses ANSI control sequences. The idea is that it would work
across an rs232 link from a terminal emulator to a real Coco or (and more
importantly for me) work on a virtual terminal on my NitrOS9 multicomp
system.
Here's a fragment of the original source code (I added the line numbers for
reference):
1: _rename pshs a,b,x,y
2: @repeat clra
3: ldb <height+1
4: decb
5: lbsr _gotoxy
6: lbsr _clrlin
7: ldb <height+1
8: lbsr _gotoxy
9: lbsr _clrlin
Assume that the output device is 80 col by 25 row and the height is stored
as a 16-bit value, so
that line 3 loads "25" into B.
The call in line 5 has A=0, B=24
The call in line 8 has A=0 (assuming A is preserved), B=25
Questions:
1/ why not do this:
1: _rename pshs a,b,x,y
2: @repeat clra
3: ldb <height+1
4:
5: lbsr _gotoxy
6: lbsr _clrlin
7: decb
8: lbsr _gotoxy
9: lbsr _clrlin
2/ is the corner of the screen 0,0 or 1,1 (or something else? I'm puzzled
by the A=0, B=25 which seems contradictory)
3/ is the corner (0,0 or whatever) the top-left corner or some other corner?
(For reference, an ANSI screen has the top-left corner as 1,1)
Thanks in advance for any enlightenment
Neal.
More information about the Coco
mailing list