Converting Mixed-Language Source Files
This directory contains mixed-language example programs and macros.
The following source files are the sample programs from Chapter 6,
"Assembly-to-High-Level Interface," of the Mixed-Language Programming
Guide:
BA.ASM Assembly module to be called from BASIC
CA.ASM Assembly module to be called from C
FA.ASM Assembly module to be called from FORTRAN
PA.ASM Assembly module to be called from Pascal
BAMAIN.BAS BASIC main program that calls assembly module
CAMAIN.C C main program that calls assembly module
FAMAIN.FOR FORTRAN main program that calls assembly module
PAMAIN.PAS Pascal main program that calls assembly module
In addition, the following files are provided:
POWER2.ASM Macro version of assembly module that can be called
from BASIC, C, FORTRAN, or Pascal.
MIXED.INC Mixed language macros.
MIXED.DOC This file.
The version of MIXED.INC provided with MASM 5.1 is smaller than the
MASM 5.0 version because most of the functionality has now been built
into MASM and the macros are no longer needed. The following macros
are still supported in MIXED.INC:
Macro Purpose
ifFP Assembles statement if the memory model uses far data
FP Provides ES override if the memory model uses far data
pLes Loads data (through ES for far data)
pLds Loads data (through DS for far data)
To use these macros with MASM 5.1, you should include MIXED.INC after
using .MODEL. The macro syntax is shown below:
ifFP statement
Assembles the statement if the memory model uses far data. This
macro can be used to push segment registers or take other
action that is only required for far data. For example,
ifFP push ds
pushes the DS register in compact, large, and huge memory
models, but has no effect in small and medium models.
FPoperand
Gives an ES override if the memory model uses far data. In
models that use near data, FP is null. For example,
mov ax,FP[bx]
assembles as
mov ax,es:[bx]
in compact, large, and huge memory models, but as
mov ax,[bx]
in small and medium models.
pLes register,address
pLds register,address
Loads a pointer from the specified address to the specified
register. If the memory model uses far data, the segment
portion of the address will be moved into ES or DS, depending
on the macro used. For example,
pLes bx,arg1
is assembled as
les bx,arg1
in compact, large, and huge memory models, but as
mov bx,arg1
in small and medium models.
The other macros in the MASM 5.0 version of MIXED.INC are provided for
compatibility with MASM 5.0, but are not documented. The rest of this
file discusses compatibility options for source code that uses 5.0
high-level-language macros. If you did not own MASM 5.0, you should
ignore the rest of this file. Do not use the other macros in
MIXED.INC.
You can use the following macros if you have source code that uses the
macros provided with MASM 5.0.
Macro Purpose
setModel Sets memory model passed from a DOS command line.
No longer needed because the expression operator
now enables you to evaluate text macros passed
from the command line directly.
hProc Initializes a procedure. Replaced by new
attributes of the PROC directive when you
specify a language argument to the .MODEL
directive.
hLocal Initializes local variables. Replaced by new
functionality of the LOCAL directive.
hRet Returns from a procedure. Replaced by new
functionality of the RET instruction.
hEndp Terminates a procedure. Replaced by new
functionality of the ENDP directive.
The 5.1 versions of these macros are different than the MASM 5.0
versions. The new macros use new MASM features to simulate the same
functionality more efficiently. Do not use the MIXED.INC provided with
MASM 5.0. It will not work under MASM 5.1.
Rather than use the old macros, you may want to convert your source
files to use the built-in mixed language features of MASM 5.1. The
conversion is straightforward and can be done easily with a text
editor.
The following changes can be made to source files that use macros from
the 5.0 MIXED.INC. The source file POWER2.ASM on the MASM 5.1
distribution disk is an example of a converted source file. You can
compare it with the POWER2.ASM supplied with MASM 5.0.
o You must define a a memory model argument and a language argument
to the .MODEL directive to use the new mixed-language features of
MASM 5.1. You can do this within the source file:
.MODEL small, c
Alternately, you can pass the arguments in from the command line
using /D. In MASM 5.0, you had to use the setModel macro to
receive a model argument passed on the command line. You only
needed to define the language symbol "cLang" for C; no
definition was needed for other languages.
The 5.0 source line to accept the argument would be:
setModel
For MASM 5.1, change to:
% .MODEL model,lang
Notice that the expression operator (%) is required so that MASM
can evaluate text arguments passed from the command line.
The 5.0 command line to define C small model would be:
MASM /MX /Dmodel=small /DcLang power2;
For MASM 5.1, change this to:
MASM /MX /Dmodel=small /Dlang=C power2;
o Replace references to the hProc macro with the PROC directive.
Remember, new features of the PROC directive only work when a
language argument is given for the .MODEL directive. The 5.0
macro syntax was:
hProc <name [NEAR|FAR]> [,<USES reglist>] [,arglist]
The 5.1 syntax is:
name PROC [NEAR|FAR] [,USES reglist] [,arglist]
The syntax for each MASM 5.0 argument in the arglist was
argument[:[NEAR|FAR] type]
where the type could be BYTE, WORD, DWORD, FWORD, QWORD, TBYTE, or
PTR (to indicate that the variable is a pointer).
The syntax for each MASM 5.1 argument is:
argument[:[[NEAR|FAR] PTR] type]
where the type can be BYTE, WORD, DWORD, FWORD, QWORD, TBYTE, or a
structure type. Note that structure types can now be given. Also,
PTR is part of the syntax rather than a type. If PTR is given with
a type, then it means that the variable is a pointer to a variable
of the given type. This information makes no difference in what
MASM assembles, but it can be used by the CodeView debugger.
For example, consider the following MASM 5.0 source line:
hProc <doTask FAR>, <USES si di>, count:BYTE, array:PTR, number
It should be changed to the following for MASM 5.1:
doTask PROC FAR USES si di, count:BYTE, array:PTR WORD, number
Notice that the array is now declared as pointer to a word (or an
array of words). In the 5.0 syntax it was simply a pointer to an
object of undefined size.
o Replace references to the hLocal macro with the LOCAL directive.
The syntax for the 5.0 hLocal macro was:
hLocal varlist
The MASM 5.1 syntax is:
LOCAL varlist
The syntax for each 5.0 variable was:
variable[:[NEAR|FAR] type]
The syntax for each 5.1 variable is:
variable[[count]][:[[NEAR|FAR] PTR] type]
The difference is the same as the difference for arguments to the
PROC directive. In addition, you can allocate local arrays by
specifying a count (in brackets) following the variable name. For
example:
LOCAL work[20]:WORD, string:PTR BYTE
This allocates a local array of 20 words called "work" and a
pointer to byte (called "string").
o Replace references to the hRet macro with the RET instruction.
o Replace references to the hEndp macro with the ENDP directive
preceded by the procedure name. For example, change
hEndp
to
procname ENDP
o Under MASM 5.1, labels within a procedure are local to the
procedure if the language argument is given for the .MODEL
directive. For example, if you use the label "exit:" in one
procedure, you can use it again in another procedure. A label
inside a procedure can be made global to the source file by
putting two colons after it (example, "glabel::"). Under MASM
5.0 all labels were global to the source file.
o Note that the 5.0 macros did not automatically handle 80386
features such as 32-bit pointers. The 5.1 features do. For
example, if you use the .386 directive before the .MODEL directive
to enable 32-bit segments, near pointers declared with PTR will be
32 bits wide and far pointers will be 48 bits wide.
