Clever Use of consortium and location segments

When I was a beginner at the C-language union, I was always wondering where to use it. Even a year before my work, I basically thought union was useless until I saw a lot of code written by cool, I am deeply impressed with the endless learning experience!

For more information about the code, see the following application scenarios:

In hardware programming, bitwise operations are often performed, assuming that the Register is 8 bits (here it is a bit too lazy to write 32 bits ), and the address of a register is 0x10. Now I want to read and write the register.

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1. Typedef unsigned char uchar;
2. Uchar * ADDR = (uchar *) 0x10;
4. If I want to view the value of a bit in the register
5. (1) uchar value = * ADDR;
6. (2) perform bitwise operations on the value to view the value of a bit.
8. If I want to write a value to a bit in the register
9. Follow these steps:
10. (1) Value = * ADDR;
11. (2) modify the value of value through bitwise operation
12. (3) * ADDR = value; then write the value back to the Register.
14. Bit operations are troublesome and it is not intuitive to write code.

Until you see such code ~!

 

 

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1. Typedef struct {
2. Uchar bit0: 1;
3. Uchar bit1: 1;
4. Uchar bit2: 1;
5. Uchar bit3: 1;
6. Uchar bit4: 1;
7. Uchar bit5: 1;
8. Uchar bit6: 1;
9. Uchar bit7: 1;
10. } Bits;
11. Typedef Union {
12. Uchar data_char;
13. Bits data_bits;
14. } Utype;
16. Uchar * ADDR = (uchar *) 0x10;
17. Utype value;
18. Value. data_char = * ADDR;
20. If you want to view a bit, such as 3rd bits
21. You can view value. data_bits.bit3 directly.
24. If you want to set a bit, for example, set 0th bits to 1 and 7th bits to 0
25. Value. data_bits.bit0 = 1;
26. Value. data_bits.bit7 = 0;
27. * ADDR = value. data_char;