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ARM Assembly Language Reference Card

• Notes about the ARM assembly language reference card:

  • cd is used for B and other instructions

  • S forces the CCR to be set based on the instruction being executed.

  • um (Skip because we will be using PUSH and POP instructions.)

  • reg refers to registers r0 to r15 or SP, LR, or PC.

  • arg refers to #imm``8 or reg or reg, shift.

  • mem (Will get to this when we get to the addressing modes.)

  • shift referes to method: logical, arithmetic, rotate and direction: right, left.

  Do NOT use STM and LDM since these might not work properly (?). Instead, use push and pop respectively.

• Byte addressing, half-word addressing, word addressing

  • LDRB, LDRH, LDR, respectively

  • You cannot directly read half-byte.

    • To do that, first read the full byte and mask off the other half-bytes.

• Bit banding

  • ARM supports special way to directly access a bit.

    xxxxxxxxxx
    3
    1
    LDRB R0, [AD]
    2
              --
    3
              bit band alias address (each bit in a byte has its own alias)
    

  • This bit banding feature is only available for SRAM(only the first 1 MB) and Peripheral(only the first 1 MB) region of the (virtual) memory.

  • Bit banding provides atomic operations to bit data.

    • Those operations will not be interrupted by the system exceptions or interrupts of the processor.