Article: Q34466
Product(s): See article
Version(s): 5.10 | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_masm
Last Modified: 12-JAN-1989
The following information was taken from the MASM 5.10 MACRO.DOC file.
Calling Macros in DOS.INC and BIOS.INC
You are responsible for saving and restoring registers used in macros.
The "Registers used" field identifies registers to save.
Macros that accept address parameters use internal macros that allow
you to specify addresses in several ways. The macro automatically
identifies the type of the argument and handles it appropriately. For
example, assume the following declarations:
String DB "test$"
pString DW Str
fpString DD Str
Given these values, the macro @DispStr (which displays the string at
DS:DX) has the following effects:
Kind of argument Example Value loaded
Label of byte variable @DispStr String DS:OFFSET String
Near pointer variable @DispStr pString DS:pString
Far pointer variable @DispStr fpString
fpString[2]:fpString[0]
Constant @DispStr 0 DS:0
Pointer in register @DispStr si DS:SI
Near Pointer with segment @DispStr pString,es ES:pString
Constant with segment @DispStr 0,es ES:0
Register with segment @DispStr di,es ES:DI
Note that if a far pointer or a segment is given, DS must be saved
before the macro call and restored afterward. Segments may be given as
registers, constants, or word variables.
In syntax, parameters enclosed in brackets are optional. Paramaters
sometimes have a leading symbol to indicate that the argument must
have a certain type, as shown below:
Leading Symbol Example Limitation
# #return Must be constant
& &vector Must be offset address as described
above
$ $terminator May be constant or register, but not
memory
Parameters with no leading symbol may be constants, registers, or
variables. Parameters are 16-bit except where noted in the
description.
Symbols must be previously defined before they can be passed as
arguments to most of the DOS macros. Generally this means that data
must be declared before code in the source file.