This document assumes some familiarity with assembly language programming and should be read after studying the tutorial <pyboard_tutorial_assembler>. For a detailed description of the instruction set consult the Architecture Reference Manual detailed below. The inline assembler supports a subset of the ARM Thumb-2 instruction set described here. The syntax tries to be as close as possible to that defined in the above ARM manual, converted to Python function calls.
Instructions operate on 32 bit signed integer data except where stated otherwise. Most supported instructions operate on registers R0-R7 only: where R8-R15 are supported this is stated. Registers R8-R12 must be restored to their initial value before return from a function. Registers R13-R15 constitute the Link Register, Stack Pointer and Program Counter respectively.
Where possible the behaviour of each instruction is described in Python, for example
- add(Rd, Rn, Rm)
Rd = Rn + Rm
This enables the effect of instructions to be demonstrated in Python. In certain case this is impossible because Python doesn't support concepts such as indirection. The pseudocode employed in such cases is described on the relevant page.
The following sections details the subset of the ARM Thumb-2 instruction set supported by MicroPython.
asm_thumb2_mov.rst asm_thumb2_ldr.rst asm_thumb2_str.rst asm_thumb2_logical_bit.rst asm_thumb2_arith.rst asm_thumb2_compare.rst asm_thumb2_label_branch.rst asm_thumb2_stack.rst asm_thumb2_misc.rst asm_thumb2_float.rst asm_thumb2_directives.rst
These sections provide further code examples and hints on the use of the assembler.
asm_thumb2_hints_tips.rst
Assembler Tutorial <pyboard_tutorial_assembler>- Wiki hints and tips
- uPy Inline Assembler source-code, emitinlinethumb.c
- ARM Thumb2 Instruction Set Quick Reference Card
- RM0090 Reference Manual
- ARM v7-M Architecture Reference Manual (Available on the ARM site after a simple registration procedure. Also available on academic sites but beware of out of date versions.)