汇编请教。。8位机汇编32位乘法算法。。。

pdwdzz · 发表于 2018-9-1 22:58:37

用到一低端8位MCU ,有一个8位乘法器，能一个周期计算8位*8位，结果存放在RH,RL两个8位寄存器中。有于MCU资源有限，想请教有没有比较节省RAM和ROM的算法。计算32位*32位 DATA1:4 * DATA2:4 -> RESULT:8

edmund1234 · 发表于 2018-9-1 22:58:38

本帖最后由 edmund1234 于 2018-9-2 14:17 编辑

以51为例， Z = X * Y , 这是UNSIGNED，不检测OVERFLOW

      MOV             A,X_0
      MOV             B,Y_0
      MUL             AB
      MOV             Z_0,A             ; Z_01 = X_0 * Y_0
      MOV             Z_1,B
      ;
      MOV             A,X_0
      MOV             B,Y_1
      MUL             AB
      ADD       A,Z_1
      MOV             Z_1,A
      MOV             A,B
      ADC             A,#0
      MOV             Z_2,A             ; Z_12 += X_0 * Y_1
      ;
      MOV             A,X_1
      MOV             B,Y_0
      MUL             AB
      ADD       A,Z_1
      MOV             Z_1,A
      MOV             A,B
      ADC             A,Z_2
      MOV             Z_2,A             ; Z_12 += X_1 * Y_0
      ;
      MOV             A,X_1
      MOV             B,Y_1
      MUL             AB
      ADD       A,Z_2
      MOV             Z_2,A
      MOV             A,B
      ADC             A,#0
      MOV             Z_3,A             ; Z_23 += X_1 * Y_1
      ;
      " " " "                               ; Z_34 += X_1 * Y_2
      " " " "                               ; Z_34 += X_2 * Y_1
      " " " "                               ; Z_45 += X_2 * Y_2
      " " " "                               ; Z_56 += X_2 * Y_3
      " " " "                               ; Z_56 += X_3 * Y_2
      " " " "                               ; Z_67 += X_3 * Y_3