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asm_thumb2_mov.rst
asm_thumb2_mov.rst 944 B
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.