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Diffstat (limited to 'docs/reference/asm_thumb2_mov.rst')
| -rw-r--r-- | docs/reference/asm_thumb2_mov.rst | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/docs/reference/asm_thumb2_mov.rst b/docs/reference/asm_thumb2_mov.rst new file mode 100644 index 0000000000..e42460881e --- /dev/null +++ b/docs/reference/asm_thumb2_mov.rst @@ -0,0 +1,28 @@ +Register move instructions +========================== + +Document conventions +-------------------- + +Notation: ``Rd, Rn`` denote ARM registers R0-R15. ``immN`` denotes an immediate +value having a width of N bits. These instructions affect the condition flags. + +Register moves +-------------- + +Where immediate values are used, these are zero-extended to 32 bits. Thus +``mov(R0, 0xff)`` will set R0 to 255. + +* mov(Rd, imm8) ``Rd = imm8`` +* mov(Rd, Rn) ``Rd = Rn`` +* movw(Rd, imm16) ``Rd = imm16`` +* movt(Rd, imm16) ``Rd = (Rd & 0xffff) | (imm16 << 16)`` + +movt writes an immediate value to the top halfword of the destination register. +It does not affect the contents of the bottom halfword. + +* movwt(Rd, imm30) ``Rd = imm30`` + +movwt is a pseudo-instruction: the MicroPython assembler emits a ``movw`` and a ``movt`` +to move a zero extended 30 bit value into Rd. Where the full 32 bits are required a +workround is to use the movw and movt operations. |