MSP430组件中的移位加法乘法

问题描述

我正在编写一个程序，该程序计算2的幂，并使用答案填充两个数组（一个数组使用硬件乘法器，第二个数组使用软件乘法）。在这种情况下，软件乘法需要使用Shift-and-Add算法。我迷失在如何在我的代码中实际实现这一点。如果有人可以提供帮助，我将永远感激不已。

            .cdecls C,LIST,"msp430.h"       ;Include device header file

        .def    RESET                   ;Export program entry-point to
                                        ;make it kNown to linker.
        .def    hcalc_power
        .def    scalc_power
        .def    SW_Mult
        .def    HW_Mult

        .text                           ;Assemble into program memory.
        .retain                         ;Override ELF conditional linking
                                        ;and retain current section.
        .retainrefs                     ;And retain any sections that have
                                        ;references to current section.
        .data
b:      .int    2                       ;Create variable and initialize it to 2
hval:   .int    1                       ;Create variable for product placement init 0
sval:   .int    1                       ;Create variable for product placement init 0
hwarr:  .int    2,2,2           ;hw mult array
swarr:  .int    1,1,1           ;sw mult array

RESET:  mov.w   #__STACK_END,SP         ;Initialize stack pointer
        mov.w   #WDTPW|WDTHOLD,&WDTCTL  ;Stop watchdog timer

;-------------------------------------------------------------------------------
; Main loop
;-------------------------------------------------------------------------------
main:   mov.w   #hwarr,R7      ;starting address of hwarr to R7
        mov.w   #swarr,R8      ;starting address of swarr to R8
        clr.w   R9
        mov.w   b,R5           ;pass b to R5 for calc_power

hwnext: mov.b   @R7+,R9        ;get next hwarr element
        cmp     #2,R9          ;is it a 2?
        jne     swnext          ;if not,go to swnext
        call    #hcalc_power    ;calculate powers of 2 -- takes 36 cc
        mov.w   hval,0(R7)     ;put product into current array element
        inc.w   R7              ;increment R7 or it won't fully move to next element
        jmp     hwnext          ;loop

swnext: mov.b   @R8+,R9        ;get next swarr element
        cmp     #1,R9          ;is it a 1?
        jne     lend            ;if not,go to end
        call    #scalc_power    ;calculate powers of 2 again -- takes
        mov.w   sval,0(R8)     ;put product into current array element
        inc.w   R8              ;increment R8 or it won't fully move to next element
        jmp     swnext          ;loop

hcalc_power:
        mov.w   hval,R6        ;pass hval to R6 for HW_Mult
        call    #HW_Mult
        ret

scalc_power:
        mov.w   sval,R6        ;pass sval to R6 for SW_Mult
        call    #SW_Mult
        ret

HW_Mult:
        mov.w   R5,&MPY        ;get R5
        mov.w   R6,&OP2        ;get R6
        nop                     ;3 clock cycles
        nop
        nop
        mov     RESLO,&hval    ;multiply and put product in hval
        ret

SW_Mult:
    
        ret

lend:   nop

;-------------------------------------------------------------------------------
; Stack Pointer deFinition
;-------------------------------------------------------------------------------
        .global __STACK_END
        .sect   .stack

;-------------------------------------------------------------------------------
; Interrupt Vectors
;-------------------------------------------------------------------------------
         .sect   ".reset"               ; MSP430 RESET Vector
         .short  RESET
         .end

解决方法

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