gnupic: gpasm numbers
Subject:
gpasm numbers
From:
Craig Franklin ####@####.####
Date:
24 Aug 2004 05:52:37 +0100
Message-Id: <4129DA4D.40905@users.sourceforge.net>
A few questions have come up recently about gpasm number representations.
Section 3.2.3 of the gputils manual covers numbers for gpasm. This
section recommends that you represent all numbers using the formats:
base general syntax 21 decimal written as
===============================================
binary B'[01]*' B'10101'
octal O'[0-7]*' O'25'
decimal D'[0-9]*' D'21'
hex H'[0-F]*' H'15'
hex 0x[0-F]* 0x15
There are several other legacy formats that gpasm supports for mpasm
compatibility. Most of these formats have shortcomings. For example
"21d" is another way to represent "21 decimal". The problem is that 'd'
is a hex character so "21d" could also mean "0x21d". So gpasm uses the
same hack that mpasm does, if the default radix is hex, "21d" is a hex
number, otherwise it is decimal 21. This is one example, there are many
more. So please don't use the other representations.
Using the numbers above are also immune to an inadvertent default radix
change. I don't recommend relying on the default radix for your code to
assemble correctly. There are too many ways that it can cause problems.
There is one real bug in gpasm's number representations. Certain
numbers like "14000" are treated as processor names instead of numbers.
This is a hack that really needs to be fixed. I haven't had time.
Although if you use one of the recommended representations in the table
above you won't have a problem.
