Re: Assembly Help!!

From: John Williams (jwilliams_at_itee.uq.edu.au)
Date: 07/22/03 

Date: Tue, 22 Jul 2003 10:44:04 +1000

Marty wrote:
> 1) It's a MMU page table making code. I don't understand '->' marked
> parts.
> It seems like to me that they're macro commands in macro definition. I
> mean, It seems like using macro command even though PT_ENTRY macro
> definition is not yet finished. and why they need some arguments
> within double quote??? What does that mean???

It's a recursive macro. Here's a simple example:

.MACRO RECURSIVE_TEST value
.if \value
   .long \value
   RECURSIVE_TEST "(\value-1)"
.else
   .long 0x9999
.endif
.ENDM

Write out by hand what will be generated if you call this RECURSIVE_TEST
macro with a value of, say, 4... it will create the following output:

.long 4
.long 3
.long 2
.long 1
.long 0x9999

When you understand why, you'll be able to understand the PT_ENTRY macro.

The quotes are probably just to get around some text substitution rules
in the assember input format.

Cheers,

John

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