.include"8535def.inc"    
       rjmp  RESET
tab:.dw 0,40,78,117,157,197,236,276,314,353,393,428,466,504,541,580,616,654
    .dw 692,730,769,808,847,887,927,968,1009,1050,1092,1134,1177,1221,1266
RESET:mov  r20,r16         ;A/D結(jié)果低5位送r20
      andi r20,$1f
      rol  r16             ;取A/D結(jié)果高5位送r17
      rol  r17
      rol  r16
      rol  r17
      rol  r16
      rol  r17
      add  r17,r17         ;r17*2
      ldi  Zh,high(tab*2)  ;取y1送r19:r18
      ldi  Zl,low(tab*2)      
      add  Zl,r17
      lpm
      mov  r18,r0
      adiw Zl,1
      lpm
      mov  r19,r0
      adiw Zl,1            ;取y2送r17:r16
      lpm
      mov  r16,r0
      adiw Zl,1
      lpm
      mov  r17,r0
      sub  r16,r18         ;求y2-y1
      sbc  r17,r19
      mov  r23,r18         ;保存y1送r24:r23
      mov  r24,r19
      mov  r18,r20         ;求（y2-y1)*(x-x1)/32
      clr  r19
      rcall mpy16s
      rol  r18
      rol  r19
      rol  r20
      rol  r18
      rol  r19
      rol  r20
      rol  r18
      rol  r19
      rol  r20
      add  r23,r19         ;求y
      adc  r24,r20
here: rjmp here

mpy16s:	                   ;16位*16位帶符號乘法
      clr	r21        ;清結(jié)果和進位位
      sub	r20,r20	
      ldi	r22,16	   ;初始化循環(huán)計數(shù)器
m16s_1:
      brcc	m16s_2	   ;進位位為 0 ，跳至m16s-2	
      add	r20,r16	   ;進位位為 1 
      adc	r21,r17	   ;結(jié)果3字節(jié)2字節(jié)加被乘數(shù)
m16s_2:
      sbrc	r18,0	   ;如果當前位置位
      sub	r20,r16	   ;從結(jié)果字節(jié)2中減被乘數(shù)低字節(jié)
      sbrc	r18,0	   ;如果當前位置位
      sbc	r21,r17	   ;從結(jié)果字節(jié)2中減被乘數(shù)低字節(jié)
      asr	r21        ;算術(shù)右移結(jié)果和乘數(shù)
      ror	r20
      ror	r19
      ror	r18
      dec	r22        ;循環(huán)計數(shù)器減 1 
      brne	m16s_1     ;如沒完成，再循環(huán)	
      ret