RPi_Assembly/ch-02/movexamps.s

@
@ Examples of the MOV instruction.
@
.global _start      @Provide program starting address

@ Load R2 with 0x4F5D6E3A first using MOV and MOVT
_start:
    MOV     R2, #0x6E3A
    MOVT    R2, #0x4F5D

@ Just move R2 into R1
    MOV     R1, R2

@ Now let's see all the shift versions of MOV
    MOV     R1, R2, LSL #1      @ Logical shift left
    MOV     R1, R2, LSR #1      @ Logical shift right
    MOV     R1, R2, ASR #1      @ Arithmetic shift right
    MOV     R1, R2, ROR #1      @ Rotate right
    MOV     R1, R2, RRX         @ Rotate extended right

@ Repeat the above shifts using
@       the Assembler mnemonics
    LSL     R1, R2, #1          @ Logical shift left
    LSR     R1, R2, #1          @ Logical shift right
    ASR     R1, R2, #1          @ Arithmetic shift right
    ROR     R1, R2, #1          @ Rotate right
    RRX     R1, R2              @ Rotate extended right

@ Example that works with 8 bit immediate and shift
    MOV     R1, #0xAB000000     @ Too big for #imm16

@ Example that can't be represented and
@       results in an error
@ Uncomment the instruction if you want to
@       see the error
@   MOV     R1, #X0ABCDEF11     @ Too big for #imm16

@ Example of MVN
    MVN     R1, #45

@ Example of a MOV that the Assembler will
@       change to MVN
    MOV     R1, #0xFFFFFFFE     @ (-2)

@ Set the parameters to exit the program
@ and then call Linux to do it.
    MOV     R0, #0              @ Use 0 return code
    MOV     R7, #1              @ Service command code 1
    SVC     0                   @ Call Linux to terminate