Can i use the same ARM assembly for different ARM processors (Cortex,Tegra and so on)?

Question

I'm interested if ARM assembly common for all types of ARM's? For example if I write some function in ARM assembly will it works the same on Cortex, Nvidia Tegra, Qualcomm etc? Can I use the same instruction set or SIMD engines or NEON on different ARM processors (like in x86-64 assembly)?

Answer 1

You list Cortex, Nvidia Tegra, and Qualcomm in one sentence which is sort of mixing concepts - Cortex is the name of the CPU core family developed by ARM, while Tegra names a system-on-chip using ARM CPU, e.g. Tegra 2/3 chips use Cortex-A9 cores.

What's important for you is the instruction set supported by each of the target chips, which in turn depends on ARM core used. This overview of existing ARM cores can be a good starting point. Also, this diagram from ARM's page gives a great, quick overview.

Another good document to check is ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition (you need to register for a free account to access it).

As of NEON, according to ARM web page, Cortex-A7, Cortex-A8 and Cortex-A15 cores are equipped with NEON by default, while for Cortex-A5 and Cortex-A9 it's optional feature (i.e. chip manufacturer decides about including it). Again, you have to consult the chip's datasheet in this case to check if NEON is supported.