Re: [Freedos-devel] [Freedos-cvs] freecom/lib c16.mac, NONE, 1.1 app_get.c, 1.2, 1.3 beep_l.c, 1.2, 1.3 beep_n.c, 1.2, 1.3 cd_dir.c, 1.6, 1.7 cmdinput.c, 1.5, 1.6 critrchk.c, 1.2, 1.3 farread.c, 1.2, 1.3 fcompl2.c, 1.2, 1.3 fdattr.c, 1.2, 1.3 fdsattr.c, 1.3, 1.4 goxy.c, 1.2, 1.3 hdlrctxt.c, 1.1, 1.2 inputdos.c, 1.3, 1.4 keyprsd.c, 1.2, 1.3 mk_rddir.c, 1.4, 1.5 msg_dps.c, 1.3, 1.4 msg_prmp.c, 1.2, 1.3 mux_ae.c, 1.5, 1.6 prprompt.c, 1.3, 1.4 showcmds.c, 1.3, 1.4 timeget.c, 1.2, 1.3 timeset.c, 1.2, 1.3 truncate.c, 1.2, 1.3 vcgetch.c, 1.2, 1.3 vcgetstr.c, 1.2, 1.3

[Alain M.]

HI Blair,

This is a nice discovery from Arkady: from his explanation below, intr() 
has CY=1 for int 21h :)

Arkady, see below

Arkady V.Belousov escreveu:
> AM> Yes. it leaves it uninitialized!
> 
>      No, CF state _always_ initialized, but initialization value depends
> from (internal) code of int*() function.
> 
>      And quick observation of intr() source code shows, that before calling
> interrupt, CF is 1 before INT 0-25 and 0 before INT 26-FF (see cmp/jb and
> cmp/ja below):
> 
> asm     cmp     al, 025h
> asm     jb      NormalIntr
> asm     cmp     al, 026h
> asm     ja      NormalIntr
> [...a lot of "asm mov"...]
> asm     jmp     SetRegs
> NormalIntr:
> asm     mov     byte ptr Code+5, 0CAh
> asm     mov     word ptr Code+6, 2
> SetRegs:
> [...a lot of "asm lds/push/mov"...]
>         /* Call the interrupt routine */
>         (* Vector)();
> 
>>> AB> Of course using asm{} is more efficient, but is not C++.
>>>      This depends. First, yes - in OW asm{} forces saving all registers on
>>> stack (even if in asm{} no registers used), but TC/BC is smarter in this
>>> (they check, which registers mentioned in instructions).
> AM> IMHO, for portability, there could be an asm function to do those
> AM> things.
> 
>      (Inline) asm function does _not_ better for portability (unless there
> is no C-like way to perform required task).

Well, it can help if used judiciously: Andreas made a lib that I use 
which is BC31 16 bits and OW 32 bits. What he did is to have a very 
limited set of functions that perform special tasks and are inline asm 
with conditionals. It works, but for too many functions it could be a PITA

> AM> It is just too bad that just one bit got left out of the
> AM> Standard/Borland functions...
> 
>      ?

The CY bit was consireded as not-important by someone.

Alain


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