Earthbound Health Incrementer

checkHealth:            ; Check the health
    lda $9A13           ; Load the value stored in address 9A13 into the accumulator
    cmp #$FF            ; Compare the value in the accumulator to 255
    bne incrementHealth ; Branch to incrementHealth if the value is not 255
    rts                 ; Return to the place where the subroutine was called if the health is 255

incrementHealth:        ; Increment the health
    inc a               ; Increment the value in the accumulator by 1
    sta $9A13           ; Store the value in the accumulator into memory address 9A13
    rts                 ; Return to the place where checkHealth was called