How to check how a bit is set in c?

[vinothmct]

How to check a bit in a variable whether it is set or not using C language

 

[tpetar]

**broken link removed**

https://www.mikroe.com/chapters/view/16/chapter-3-pic16f887-microcontroller/


Read and other chapters.

 

[alexan_e]

Read https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=37871

 

[spudboy488]

This is what I use for 8-bit testing.

bit bit_test(unsigned char Tval, unsigned char B) {

	unsigned char TestVal=1;
	
	TestVal=TestVal<<B;
	
	if (Tval & TestVal)
		return 1;
	else
		return 0;
}

 

[alexan_e]

A set of macro can do that without spending any resources

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// add this defines
#define SETBIT(ADDRESS,BIT) (ADDRESS |= (1<<BIT)) 
#define CLEARBIT(ADDRESS,BIT) (ADDRESS &= ~(1<<BIT)) 
#define FLIPBIT(ADDRESS,BIT) (ADDRESS ^= (1<<BIT)) 
#define CHECKBIT(ADDRESS,BIT) (ADDRESS & (1<<BIT)) 
#define WRITEBIT(RADDRESS,RBIT,WADDRESS,WBIT) (CHECKBIT(RADDRESS,RBIT) ? SETBIT(WADDRESS,WBIT) : CLEARBIT(WADDRESS,WBIT))
 
// and then you can use
SETBIT(PORTX,2);  // set bit2 of portx (set to 1)
SETBIT(PORTY,0);  // set bit0 of porty
 
CLEARBIT(PORTX,5); // clear bit5 of portx (set to 0)
 
FLIPBIT(PORTX,2);  // invert bit2 of portX, if it was 1 it becomes 0, and if 0 becomes 1
                    // example for portx 0x10101010 the result is 0x10101110
                    
if (CHECKBIT(PORTX,4)) {} else {} // result is true if bit4 of portx is 1, false if it is 0
if (!CHECKBIT(PORTX,4)) {} else {} // result is true if bit4 of portx is 0, false if it is 1
 
 
WRITEBIT(PORTX,0,PORTY,2);   // copy the bit0 of portx to bit2 of porty

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All the examples are for ports but they work for variables too