AVR起步教程:从51到AVR编程篇

//tmp1 = 0x0B 0000 1011

"mov %2,%1""nt" //tmp2 = 0x0B

"andi %2,0x03""nt" //tmp2 = 0x03 0000 0011

"lsl %1""nt"

"lsl %1""nt" //tmp1 = 0x02 0000 0010

"eor %1,%2""nt" //tmp1 = 0x01 0000 0001

"mov %2,%1""nt" //tmp2 = 0x01

"andi %2,0x01 ""nt" //tmp2 = 0x01 0000 0001

"lsl %1""nt" //tmp1 = 0x00 0000 0000

"eor %1,%2 ""nt" //tmp1 = 0x00 0000 0001

"andi %1,0x0f""nt" //tmp1 = 0x01

: "=d" (Data),"=d" (tmp1),"=d" (tmp2)

: "0" (Data),"1" (tmp1),"2" (tmp2)

);

return tmp1;

}

这个方法中，我们加上return共花了15条指令，比方法2来讲，又省了7条指令。