forward referencing constants

[redskull]

If my understanding is correct, then the assembler just plugs is constants as immediete values before it creates the code; if that's the case, how come you can't forward reference them?

this won't work, but it will if you swap it around (.const before .data) it will

Code Select Expand


.data
ARRAY DWORD MAX_ARRAY DUP (0)
.const
MAX_ARRAY equ 5


It seems stupid, like it should be able to work.  I'm sure there's a good reason why it doesn't, hopefully someone can enlighten me

[Ossa]

You seem to have a misunderstanding between equates and constants. Equates are "plugged in at assemble time" and are defined, as you have, with the EQU directive. Constants are values that are constant - they don't change, but are kept in the .const section and are not "plugged in" until run time. So the following is valid:

Code Select Expand

MAX_ARRAY equ 5
.data
ARRAY DWORD MAX_ARRAY DUP (0)


Having got that out of the way, your question can now be answered: MASM is a single pass assembler - that is, it starts at the beginning of the file and goes through it once, so that by the end it has finished the assembly process. As a result, it can't "plug in" equates that it doesn't yet know about.

Ossa

[redskull]

MASM is a single pass assembler...

Constants are values that are constant - they don't change, but are kept in the .const section and are not "plugged in" until run time

You learn something new everyday. Thanks! :U