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rev

rev R

指令格式

rev R

影响标志

无

伪代码描述

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R = (R >> 4) & 0x0f
  | (R << 4) & 0xf0;

指令描述

寄存器R内容的高4位和低4位交换，结果存储到寄存器R中。

指令执行前：
       7    6    5    4    3    2    1    0
    +----+----+----+----+----+----+----+----+
R = | b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 |
    +----+----+----+----+----+----+----+----+
指令执行后：
       7    6    5    4    3    2    1    0
    +----+----+----+----+----+----+----+----+
R = | b3 | b2 | b1 | b0 | b7 | b6 | b5 | b4 |
    +----+----+----+----+----+----+----+----+

范例

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mov A, #0x34    //A = 0x34
mov R, A        //R = 0x34
rev R           //R = 0x43

rev A, R

指令格式

rev A, R

影响标志

无

伪代码描述

1
2
A = (R >> 4) & 0x0f
  | (R << 4) & 0xf0;

指令描述

寄存器R内容的高4位和低4位交换，结果存储到累加器A中。

指令执行前：
       7    6    5    4    3    2    1    0
    +----+----+----+----+----+----+----+----+
R = | b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 |
    +----+----+----+----+----+----+----+----+
指令执行后：
       7    6    5    4    3    2    1    0
    +----+----+----+----+----+----+----+----+
A = | b3 | b2 | b1 | b0 | b7 | b6 | b5 | b4 |
    +----+----+----+----+----+----+----+----+

范例

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mov A, #0xC5    //A = 0xC5
mov R, A        //R = 0xC5
rev A, R        //A = 0x5C