Tracing register contents, have you gone crazy trying to trace register contents? It happens when writing assembly programs.

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80x86 Register Equates
by te987
[email protected]

Have you ever had to debug a program where most of the data was
contained in registers? (As it should be in a good assembly program.)
Have you gone crazy trying to trace register usage? (Yeah, I know that
being crazy helps when writing assembly programs!) The following
technique makes tracing register usage easy...

Simply create an equate for each register. Place the equates in an
include file and "include register.inc" at the top of every file.

Now, assemble your program using the following Turbo Assembler
command line:

tasm /l/c somefile

The /l switch instructs TASM to generate a listing, and the /c says
to create a cross reference.

(An aside: I also use MASM 6.xx, but have never been able to find
the correct switch(es) in either MASM.EXE or ML.EXE to make it
generate a cross reference. "masm /l/c somefile" generates a symbol
table, but it doesn't give the LINE NUMBERS where the symbol is used.
Most useless... If anyone knows how to do so, I would appreciate
hearing from you...)

The following three files show how to use register equates. First,
the include file:

;====== start of register.inc ================================

;====== end of register.inc ================================

Next, a "Hello, world!" program showing equated registers. The first
four lines are TASM directives controlling how the listing is created.
I normally run the == line (and comments) out to column 96. This
prints the full page width in portrait when using 16.67 characters per
inch.

;====== start of hello.asm =================================

;====== end of hello.asm =================================

Finally, the (edited) listing file. Editing consisted of deleting
extra blank lines, form feeds, and narrowing column widths so that the
listing was 72 columns wide (in particular, comments were truncated).

Notice in the symbol table that registers are cross referenced,
with, for example, register _ax being defined at line 10 (in the include
file) and used at lines 20, 21, 22, and 28. Imagine how useful a cross
reference would be if a register was used 200 times!

;====== start of hello.lst ==================================

;====== end of hello.lst ==================================

I hope this technique helps. I've been using it for years, having
first learned it in an IBM 360 mainframe environment in college.