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, imm32) Rd = imm32

movwt is a pseudo-instruction: the MicroPython assembler emits a movw followed by a movt to move a 32-bit value into Rd.