• Cortex A code / function alignment

    Hi !

    I am writing assembly code for some ARMv7a and ARMv8a CPU. I know that code has to be 4 bytes aligned, but I saw in several places (uboot/linux) the ".align 4" GCC directive, which will align to 2**4 = 16 bytes.

    When writing code that will…

  • The madman strikes again - ADD/SUB SP

    Is there something special in the instructions ADD (SP plus register, ARM) and SUB (SP minus register)?

    I didn't find anything different from the basic ADD  (register) and SUB (register) except the documentation:

    <Rd> The destination register…

  • How many states for an ARM Cortex A8?

    Hi,

    When I read about Thumb2 instructions, I have such a question: How many states for a Coretx A8? I know it has ARM and Thumb states. Thumb2 instruction is belong to Thumb state? Then does A8 have a pure Thumb instruction besides Thumb2 set?

    Thanks,

  • What does it mean 'IT can be omitted'?

    Hi,

    When I read the following on ARM website, I don't understand the first line. When I change ITTE to TE (as 'IT can be omitted"), the assembler complains an error of this line.

    Could you explain it to me?

    Thanks,

      ITTE NE ; IT can be omit…