From:	"Mr A Appleyard" <MCLSSAA2 AT fs2 DOT mt DOT umist DOT ac DOT uk>
Organization:	Materials Science Centre
To:	DJGPP AT delorie DOT com
Date:	Thu, 21 May 1998 10:13:11 GMT
Subject:	BUG in Gnu C++ (djgpp v2) mouse access under Windows 95: PS
Message-ID:	<152388C785A@fs2.mt.umist.ac.uk>

> From:     Self <UMIST-MT-FS2/MCLSSAA2>
> To:       Gnu C email circular
> Subject:  BUG in Gnu C++ (djgpp v2) mouse access under Windows 95
> Date: Thu, 21 May 1998 09:56:57 GMT
> 
>   I posted about this fault before; but since then I have deleted all my mouse
> software and bought a new mouse and installed its software, but I still have
> the fault.
>   I wrote two Gnu C++ (djgpp v2) programs that use the mouse, not by polling
> it but by supplying a mouse handler interrupt routine, by the function
> settrap() appended below, which Eli Zaretski kindly wrote for me some time
> ago. They worked OK for ages in DOS 6.22 and previous, both plain and when
> called from within Windows 3.1.1. The two programs are:-
>   AAEMACS.EXE, runs with the screen in DOS mode 3 (ordinary 80*25 char text)
>   SPATRL.EXE, runs with the screen in various graphics modes.
> 
>   But under Windows 95 (which I changed to a few weeks ago) I get faults:-
>   In `shutdown and restart in DOS mode' (= plain DOS 7), both still OK.
>   When called from Win95, or from DOS 7 which was called in a Win95 window:-
>     SPATRL works OK.
>     AAEMACS.EXE often totally misunderstands where the mouse pointer is, and
> sometimes crashes out when I touch or handle the mouse. That is a great
> nuisance.
>   (Under DOS 6.22 and previous, AAEMACS.EXE gave similar mouse faults if I ran
> it in enlarged text modes such as 132*43 character mode.)
> /*-----*/
> void mouse::settrap(uns long mask,void (*func)(__dpmi_regs *)) {
> /* This is tricky in protected-mode. We must allocate a real-mode wrapper
>    function which will be called by the mouse driver, and which in turn will
>    switch to protected-mode and call our protected-mode handler function. */
> if(!Jerry.nbuttons) return;
> if(!func) {Jerry.handlerInstalled=0; /* remove handler */
>     _go32_dpmi_free_real_mode_callback(&cb_info); R.dx=R.es=0;}
> else { /* Allocate real-mode call-back. Find real-mode address of handler */
>     cb_info.pm_offset=(uns long)func; Jerry.handlerInstalled=1;
>     if(_go32_dpmi_allocate_real_mode_callback_retf(&cb_info,
>       (__dpmi_regs*)&cb_regs)) return;
>     R.dx=cb_info.rm_offset; R.es=cb_info.rm_segment;}
> R.ax=12; R.cx=mask; Int(0x33);}

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