1. Register shift instruction

1.1. File specification

Symbol： Rd, Rn means ARM registers R0-R15. immN means instant value with width N. These instructions affect the condition flags.

1.2. Register shift

When using immediate value, it changes from zero padding to 32 bits. So mov(R0, 0xff) 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 first half-word of the target register, which does not affect the content of the second half-word.

• movwt(Rd, imm32) Rd = imm32

movwt is a virtual instruction：The MicroPython assembler sends movw and then movt to move the 32-bit value into Rd. Move a 32-bit value into Rd with a movt.