Android/ARM UMULL support

[charles]

Hi,

I am working on an application built around my Android port of PARI/GP (computer algebra system for number theory), and was wondering if Android (or ARM platforms in general) consistently provide 32x32 -> 64 bit unsigned multiplication (UMULL).

If so, would this perform better than four MUL?

The maintainer of PARI/GP has written an ARM assembly level0 kernel for libpari, but does not know if it is usable since it is "very hard to know" if an ARM platform supports UMULL.

https://code.google.com/p/paridroid/ (Project page)

(Is this an appropriate question for android-ndk, or would it be better to ask about this on android-platform?)

Thanks.

- Charles

[Dave Butcher]

The simple answer is yes, UMULL will be available.  There is some detail though:

The NDK supports ARMv5TE or ARMv7 - in the form of armeabi and armeabi-v7a, both of these are

capable of UMULL instructions.

For armeabi binaries you will need to be in ARM state (the instruction is not supported by Thumb), for armeabi-v7 either

ARM or Thumb2 provide the instruction.

Hope that helps.

  Dave.