One good option for more portable macros in assembly is to use the C preprocessor. It doesn't always provide all the features you might like, but its behavior is defined by a standard, so it is very predictable.
The iOS toolchain applies the C preprocessor to assembly sources by default; it's been a while since I've used the mainline gnu tools, but I think it is automatically applied to .S (capital S) files by default there.
If you have more questions or issues with the iOS toolchain, please file bugs and/or post your question to the devforums. There are plenty of people who use assembler everyday who will be happy to help out.
And just to echo grandparent: the unified assembler language has been standard on ARM for several years now; pre-unified mnemonics like strneb are deprecated.
I do use C preprocessor whenever I can. But since ARM assembler uses # to refer to constants, and C preprocessor uses # for different purpose, you can't use it most of the time. I'd love to know if you have a work around.
>If you have more questions or issues with the iOS toolchain, please file bugs and/or post your question to the devforums. There are plenty of people who use assembler everyday who will be happy to help out.
Thanks. Didn't know that..
>And just to echo grandparent: the unified assembler language has been standard on ARM for several years now; pre-unified mnemonics like strneb are deprecated.
I just spent a few hours cleaning up the code to be UAL compatible. Android NDK seems to support both ".syntax unified" and ".syntax divided", but iOS assembler from xcode4.5 can only support unified. Besides the conditional instructions, with UAL enabled you can't assemble the following instruction with Android NDK's assembler:
> I do use C preprocessor whenever I can. But since ARM assembler uses # to refer to constants, and C preprocessor uses # for different purpose, you can't use it most of the time. I'd love to know if you have a work around.
My "work around", such as it is, is that the C standard says that # shall be followed by a macro parameter; if it isn't (as will be the case with # in ARM assembly) the behavior is undefined by the standard, and it happens that LLVM does the "right thing" (from the perspective of someone who wants to get things done without a lot of hassle) and simply passes the # through unchanged.
This is obviously imperfect, but it works for my purposes. It may not be sufficient for your needs.
The inability of (some builds of?) gas to support implicit sources under .syntax unified has also annoyed me.
The iOS toolchain applies the C preprocessor to assembly sources by default; it's been a while since I've used the mainline gnu tools, but I think it is automatically applied to .S (capital S) files by default there.
If you have more questions or issues with the iOS toolchain, please file bugs and/or post your question to the devforums. There are plenty of people who use assembler everyday who will be happy to help out.
And just to echo grandparent: the unified assembler language has been standard on ARM for several years now; pre-unified mnemonics like strneb are deprecated.