Fundamentals of embedded programming

Solution

#include <stdio.h>

#include <stdlib.h>

#define BITSET(reg, pos) (reg | (1 << (pos)))

#define BITCLEAR(reg, pos) (reg & (~(1 << (pos))))

#define BITTEST(reg, pos) (reg & (1 << (pos)))

int main(int argc, char* argv[])

{

unsigned char reg = 0;

int i = 0;

char buffer [9];

printf("Test bit setting\n");

for(i = 0; i < sizeof(unsigned char) * 8; ++i){

itoa (reg, buffer, 2);

printf("Before setting bit at pos %d, register status: 0b%08s\n",i, buffer);

reg = BITSET(reg, i);

itoa (reg, buffer, 2);

printf("After setting bit at pos %d, register status : 0b%08s\n",i, buffer);

}

unsigned char reg1 = 0x5A;

itoa (reg1, buffer, 2);

printf("\nTest bit testing 0b%08s\n",buffer);

for(i = 0; i < sizeof(unsigned char) * 8; ++i){

int status = BITTEST(reg1, i);

if(status){

printf("Bit at pos %d of register is set\n", i);

}

else{

printf("Bit at pos %d of register is NOT set\n", i);

}

}

printf("\nTest bit clearing\n");

for(i = 0; i < sizeof(unsigned char) * 8; ++i){

itoa (reg, buffer, 2);

printf("Before clearing bit at pos %d, register status: 0b%08s\n",i, buffer);

reg = BITCLEAR(reg, i);

itoa (reg, buffer, 2);

printf("After clearing bit at pos %d, register status : 0b%08s\n",i, buffer);

}

return 0;

}

Output

Test bit setting

Before setting bit at pos 0, register status: 0b00000000

After setting bit at pos 0, register status : 0b00000001

Before setting bit at pos 1, register status: 0b00000001

After setting bit at pos 1, register status : 0b00000011

Before setting bit at pos 2, register status: 0b00000011

After setting bit at pos 2, register status : 0b00000111

Before setting bit at pos 3, register status: 0b00000111

After setting bit at pos 3, register status : 0b00001111

Before setting bit at pos 4, register status: 0b00001111

After setting bit at pos 4, register status : 0b00011111

Before setting bit at pos 5, register status: 0b00011111

After setting bit at pos 5, register status : 0b00111111

Before setting bit at pos 6, register status: 0b00111111

After setting bit at pos 6, register status : 0b01111111

Before setting bit at pos 7, register status: 0b01111111

After setting bit at pos 7, register status : 0b11111111

Test bit testing 0b01011010

Bit at pos 0 of register is NOT set

Bit at pos 1 of register is set

Bit at pos 2 of register is NOT set

Bit at pos 3 of register is set

Bit at pos 4 of register is set

Bit at pos 5 of register is NOT set

Bit at pos 6 of register is set

Bit at pos 7 of register is NOT set

Test bit clearing

Before clearing bit at pos 0, register status: 0b11111111

After clearing bit at pos 0, register status : 0b11111110

Before clearing bit at pos 1, register status: 0b11111110

After clearing bit at pos 1, register status : 0b11111100

Before clearing bit at pos 2, register status: 0b11111100

After clearing bit at pos 2, register status : 0b11111000

Before clearing bit at pos 3, register status: 0b11111000

After clearing bit at pos 3, register status : 0b11110000

Before clearing bit at pos 4, register status: 0b11110000

After clearing bit at pos 4, register status : 0b11100000

Before clearing bit at pos 5, register status: 0b11100000

After clearing bit at pos 5, register status : 0b11000000

Before clearing bit at pos 6, register status: 0b11000000

After clearing bit at pos 6, register status : 0b10000000

Before clearing bit at pos 7, register status: 0b10000000

After clearing bit at pos 7, register status : 0b00000000

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