Thread: Logic to set more than one bits

I wanted to discuss a situation where we need to set more than two bits in a 8-bit or 16-bit or 32-bit register and explore a suitable logic

By using below approach, we can set multiple bits in a 8 -bit register

Code:

 #include<stdio.h>

void set_Bits ( char num, char set_mask)
{
	num = num | set_mask;           // 00000010 OR 00000101 = 0000 0111 = 7
	
	printf("num : %d \n", num);     // Print value 7
	
}


int main()
{
	unsigned char num = 2; // binary 0000 0010  [MSB7 -LSB0] 
	unsigned char set_mask; 
	set_mask  = (1 << 0)| (1 << 2);  // 00000001 OR 00000100 = 00000101
    printf("mask value %d \n", set_mask);
	set_Bits( num, set_mask );
	return 0;
}

This logic is adaptable to different situations like 16 bit or 32 bit

but its matter of suitable suggest good way How to set 16 bits in 32 bit register

Please let me know your thoughts on this proposed logic, if you want to offer any efficent logic

C doesn't really have the concept of "registers". You can declare variables of specific sizes, though, with types from stdint.h:

• int8_t/uint8_t: signed/unsigned 8 bits
• int16_t/uint16_t: signed/unsigned 16 bits
• int32_t/uint32_t: signed/unsigned 32 bits

The logic to set bits is the same, regardless of size. But if you're left-shifting a 1 to make a mask, cast the 1 to the appropriate type first, as in (uint32_t)1 << 18, otherwise it may not work on systems where int is smaller than the type you're using (smaller/older/embedded systems will often have 16-bit int).

Edit: yes, C does have a register keyword, but that's a hint to the compiler to keep a variable in a register. Other than that, the C language doesn't know what registers are.

I'd like to clarify that my question about setting multiple bits is within the context of embedded systems, where we can use 8-bit, 16-bit, or 32-bit microcontrollers.

I've demonstrated how I would do it for one-byte variables in an 8-bit microcontroller. Would you recommend any alternative methods for 32-bit microcontrollers?

The basic method doesn't change, whether you're on an 8-bit, 16-bit, or 32-bit microcontroller. Why do you think your code wouldn't work on a 32-bit or even a 64-bit CPU?

Setting bits is just about the simplest thing you can do, and there's not many "better" ways to do it.