In-depth understanding of computer system second exercise answers CSAPP 2.10, csapp2.10

In-depth understanding of computer system second exercise answers CSAPP 2.10, csapp2.10

For any bitwise vector a, there is a ^ a = 0. Consider the following program:

1 void inplace_swap(int *x, int *y)2 {3     *y = *x ^ *y;4     *x = *x ^ *y;5     *y = *x ^ *y;6 }

Assume that x and y point to a and B respectively. Complete the following table:

Procedure	* X	* Y
Initial	A	B
Step 1	A	A ^ B
Step 2	A ^ (a ^ B)	A ^ B
Step 3	A ^ (a ^ B)	A ^ (a ^ B)

Because the exclusive or operation satisfies the exchange rate and combination rate, and a ^ 0 = 0, a ^ = ~ A. So there are

Procedure	* X	* Y
Initial	A	B
Step 1	A	A ^ B
Step 2	B	A ^ B
Step 3	B	A