MOV .w #0h, DIGITS ; Initialise DIGIT to 0
cmp.w #0h, Result ; Check if Result count=0
jeq calc_over ; Exit if 0
call #Mul100 ; Multiply Result count by 100
call #Divide ; Divide the result with #06d
call #Hex2bcd ; Convert 16bit binary to BCD number
; Result xx.xx
calc_over ret ; Return from subroutine
;******************************************************************************
Mul100 ;subroutine for multiplying Result with 100d
;inputs Result 16bit and constant 64h (100d) 16bit
;output 32bit htX100_msw & htX100_lsw
;******************************************************************************
MOV .w #100,IROP1 ; Load IROP1 with 100 (multiplier)
mpyu clr.w htX100_lsw ; Clear buffer for least
; signifiCANt word
clr.w htX100_msw ; Clear buffer for most
; significant word
macu clr.w IROP2M ; Clear multiplier high word
L$002 bit.w #1,IROP1 ; Test actual bit
jz L$01 ; If 0: do nothing
add.w Result,htX100_lsw ; If 1: Add multiplier to Result
addc.w IROP2M,htX100_msw ;
L$01 rla.w Result ; Multiplier X 2
rlc.w IROP2M ;
rrc.w IROP1 ; Next bit to test
jnz L$002 ; If bit in carry : finished
ret
;******************************************************************************
Divide ;Subroutine for 32/16 bits division
;inputs 32bit htX100_msw & htX100_lsw and #06 16bit, output DIGIT 16bit
;******************************************************************************
clr.w DIGITS ; Clear buffer to hold new Result
MOV .w #17,IRBT ; Initialize loop counter
div1 cmp.w #06,htX100_msw ; Compare divisor with dividend high word
jlo div2 ; If less : jump to div2
sub.w #06,htX100_msw ; Subtract 6 from high word
div2 rlc.w DIGITS ; Rotate result left through carry 1 bit
jc div4 ; If carry set: finished
dec.w IRBT ; Decrement bit counter
jz div3 ; If counter = 0 : finished
rla.w htX100_lsw ; Dividend X 2
rlc.w htX100_msw ;
jnc div1 ; If carry not set jump to step div1
sub.w #06,htX100_msw ; Subtract 6 from high word
setc ; Set carry
jmp div2 ; Jump to repeat
div3 clrc ; Clear carry
div4 ret ; Return from subroutine
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本文关键字：超声波 MSP430单片机，单片机-工控设备 - MSP430单片机
