16、32bit integral number square root.txt

实用的单片机开发与应用程序

16位整型数开方

.include "8515def.inc"
          .def    numlo    = r16
          .def    numhi    = r17
          .def    sqrt     = r18
          .def    suber    = r24
          .def    suberh   = r25
; enter with the 16 bit Number in r16,r17
          .org    0x00
          rjmp    reset
          .org    0x20
reset:    ldi     r16,0x02       ; Stack Pointer Setup 
          out     SPH,r16        ; Stack Pointer High Byte 
          ldi     r16,0x5f       ; Stack Pointer Setup 
          out     SPL,r16        ; Stack Pointer Low Byte 
loopm:
          ldi     r16,0x64
          ldi     r17,0x01
          rcall   sqrt
          nop
          rjmp    loopm

Sqrt:
          clr     sqrt
          ldi     suber,1        ; initialize the seed to be subtracted
          clr     suberh         ; for each iteration
loop:    sub     numlo,suber
          sbc     numhi,suberh
          brlo    exit
          inc     sqrt
          adiw    suber,2        ; keep the number to subtract ODD.
          rjmp loop
exit: 
          ret                   ; the sqrt(num) on exit is stored in r18


.

32位整型数开方

;input r15:r14:r13:r12 (it make a copy from r3::r0)
;output r25:r24
;use r20,r21,r22,r26,r28
;输入返回数据：lsqrt(0x5300164) = 0x2471
;对应于8M晶振时开方所用时间为 48.38us;

.include "8515def.inc"
         .org 0x00
          rjmp     reset
         .org 0x20
          reset:
          ldi      r16,0x02       ; Stack Pointer Setup 
          out      SPH,r16        ; Stack Pointer High Byte 
          ldi      r16,0x5F       ; Stack Pointer Setup 
          out      SPL,r16        ; Stack Pointer Low Byte
; 验证 
;test r25:r24 = lsqrt(0x5300164)
loopm:
          ldi      r16,0x64
          mov      r12,r16
          ldi      r16,0x01
          mov      r13,r16
          ldi      r16,0x30
          mov      r14,r16
          ldi      r16,0x05
          mov      r15,r16
          rcall    lsqrt
          nop
          rjmp     loopm
         
lsqrt:
          clr      r20
          clr      r21
          clr      r22
          clr      r24
          clr      r25
          clr      r26
          ldi      r28,16
   m03:
          rol      r15
          rol      r20
          rol      r21
          rol      r22
          rol      r15
          rol      r20
          rol      r21
          rol      r22
         
          lsl      r24
          rol      r25
          rol      r26
         
          cp       r24,r20
          cpc      r25,r21
          cpc      r26,r22
          brsh     m01
          sbc      r20,r24
          sbc      r21,r25
          sbc      r22,r26
          subi     r24,-2
    m05:
    m01:
          dec      r28
          sbrs     r28,0
          sbrc     r28,1
          rjmp     m03
          breq     m08
          mov      r15,r14
          mov      r14,r13
          mov      r13,r12
          rjmp     m03
    m08:
          lsr      r26
          ror      r25
          ror      r24
          ret