什么情况下会是右移呢?

1万 · 2015-6-14 21:35

//I/O定义
sbit AD_DOUT  P1^5;
...
...
//语句
signed int AD_Value;
...
AD_Value |= AD_DOUT;
...

//反汇编结果如下:
74:       AD_Value |= AD_DOUT;
75:
C:0x09AC A295    MOV    C,AD_DOUT(0x90.5)
C:0x09AE E4    CLR    A
C:0x09AF 33    RLC    A  //左移,什么情况下是右移??
C:0x09B0 4207    ORL    0x07,A

请问语句 AD_Value |= AD_DOUT; 什么情况下会是右移呢?

2万 · 2015-6-14 21:35

//I/O定义
sbit AD_DOUT  P1^5;
...
...
//语句
signed int AD_Value;
...
AD_Value |= AD_DOUT;
...

//反汇编结果如下:
74:       AD_Value |= AD_DOUT;
75:
C:0x09AC A295    MOV    C,AD_DOUT(0x90.5)
C:0x09AE E4    CLR    A
C:0x09AF 33    RLC    A  //左移,什么情况下是右移??
C:0x09B0 4207    ORL    0x07,A

请问语句 AD_Value |= AD_DOUT; 什么情况下会是右移呢?

2万 · 2015-6-14 21:36

好办：  CY=AD_DOUT;
      CY=ACC&0X01;  //产生右移指令
      AD_Value=ACC;
      ……

编译结果：
      MOV       C,AD_DOUT
      RRC       A    ；右移
      MOV       R7,A
      MOV       R6,#00H
;---- Variable 'AD_Value?041' assigned to Register 'R6/R7' ----