12 Oct
2006
12 Oct
'06
3:18 p.m.
actually we are both wrong, the macro was used to make the call external if needed. The
near declaration was required to tell the assembler what addressing to use. If the label
was in the module being assembled, then the assembler knew what size to use.
-----Original Message-----
From: Chuck Guzis <cclist at sydex.com>
Sent: Oct 12, 2006 4:07 PM
To: cctalk at classiccmp.org
Subject: Re: MSDOS Source code leaked
On 10/12/2006 at 3:34 PM Steve Thatcher wrote:
invoke is a macro that allows for handling small
code model versus large
code model...
The INVOKE macro cited merely declares the target of the call to be NEAR if
not already defined.
By the time MASM 6 (aka ML) came out, extended INVOKE was well internalized
into MASM--and allowed parameter passing (as well as simplified segment
definitions, procedure prototypes, procedure-local labels and a host of
other worthwhile features). But this was just a formalization of what many
programmers were already doing via macros.
Cheers,
Chuck
12 Oct
12 Oct
3:45 p.m.
On 10/12/2006 at 6:18 PM Steve Thatcher wrote:
actually we are both wrong, the macro was used to make
the call external
if needed. The near declaration was required to tell the assembler what
addressing to use. If the label was in the module being assembled, then
the assembler knew what size to use.
Let's see--I said:
>The INVOKE macro cited merely declares the target
of the call to be NEAR
>if not already defined.
Which is pretty much the same thing--right? If the symbol's not already
defined (at pass 2), then it doesn't exist in the same module and is
therefore defined as an external NEAR by the macro.
If the symbol was defined later in the same module, it would be defined as
of pass 2 (hence, the IF2 conditional--a plain old IF would cause serious
problems by defining the symbol during pass 1, only to have the darned
thing crop up later).
If the CALL target needed is FAR, it would have to be defined as such.
Later versions of MASM use the PROTO definition to define things in
advance, not only with regard to the NEAR or FAR call distance, but also as
to the type and number of arguments.
Cheers,
Chuck
4:31 p.m.
let's see - I said that the external was the important declaration.
The assembler would declare it unreachable if the symbol did not
exist in the current module unless you used external, SO it is not
the same thing...
At 03:45 PM 10/12/2006, Chuck Guzis wrote:
On 10/12/2006 at 6:18 PM Steve Thatcher wrote:
actually we are both wrong, the macro was used to
make the call external
if needed. The near declaration was required to tell the assembler what
addressing to use. If the label was in the module being assembled, then
the assembler knew what size to use.
Let's see--I said:
>The INVOKE macro cited merely declares the
target of the call to be NEAR
>if not already defined.
Which is pretty much the same thing--right? If the symbol's not already
defined (at pass 2), then it doesn't exist in the same module and is
therefore defined as an external NEAR by the macro.
If the symbol was defined later in the same module, it would be defined as
of pass 2 (hence, the IF2 conditional--a plain old IF would cause serious
problems by defining the symbol during pass 1, only to have the darned
thing crop up later).
If the CALL target needed is FAR, it would have to be defined as such.
Later versions of MASM use the PROTO definition to define things in
advance, not only with regard to the NEAR or FAR call distance, but also as
to the type and number of arguments.
Cheers,
Chuck
4:57 p.m.
On 10/12/2006 at 4:31 PM Steve Thatcher wrote:
let's see - I said that the external was the
important declaration.
The assembler would declare it unreachable if the symbol did not
exist in the current module unless you used external, SO it is not
the same thing...
The difference eludes me. Maybe we're just trying to say the same thing.
If a call target isn't defined by pass 2, it isn't in the module. If the
symbol didn't exist in the current module after pass 2, the assembler
wouldn't declare it as unreachable; it would declare it as "undefined".
EXTERN declares it at pass 2 time and solves the problem--at least as far
as the assembly is concerned. If the symbol name is a typo, then there
will be a LINK error.
Note that you can't do this in MASM 6 or 7 native mode. IF2 isn't allowed
unless you specify MASM 5 compatiblity (/Zm).
Cheers,
Chuck
8:59 p.m.
most all the assemblers I have worked with required explicit
declarations for external. The assembler could certainly assume
external if not found, but it was not typical.
At 04:57 PM 10/12/2006, you wrote:
On 10/12/2006 at 4:31 PM Steve Thatcher wrote:
let's see - I said that the external was the
important declaration.
The assembler would declare it unreachable if the symbol did not
exist in the current module unless you used external, SO it is not
the same thing...
The difference eludes me. Maybe we're just trying to say the same thing.
If a call target isn't defined by pass 2, it isn't in the module. If the
symbol didn't exist in the current module after pass 2, the assembler
wouldn't declare it as unreachable; it would declare it as "undefined".
EXTERN declares it at pass 2 time and solves the problem--at least as far
as the assembly is concerned. If the symbol name is a typo, then there
will be a LINK error.
Note that you can't do this in MASM 6 or 7 native mode. IF2 isn't allowed
unless you specify MASM 5 compatiblity (/Zm).
Cheers,
Chuck
9:19 p.m.
On 10/12/2006 at 8:59 PM Steve Thatcher wrote:
most all the assemblers I have worked with required
explicit
declarations for external. The assembler could certainly assume
external if not found, but it was not typical.
...and that's why I think MASM 6 and 7 are heads above MASM 5 and its
predecessors.
For instance:
.model small,c
.code
Flip proto Hither:word
Flap proto Yonder:word
Flip proc Hither:word
invoke Flap,Hither
Flip endp
end
"Flap" is automatically assumed to be external. Simplifies life so much...
Cheers,
Chuck
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