Construct UART Data Frame with Parity Bit

Code

#include <stdio.h>
#include <stdint.h>

typedef struct {
    uint8_t parity_enable : 1;
    uint8_t parity_type   : 1;
    uint8_t reserved      : 6;
} UART_Control;

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    if(!ctrl->parity_enable)
    {
        return data;
    }

    else
    {   
        // check if odd parity
        if(ctrl->parity_type==1)
        {
            uint8_t count=0;

            for(uint8_t i=0;i<7;i++)
            {
                if((1<<0)&(data>>i))
                {
                    count++;
                }
            }

            if(count%2==0)
            {
                data|=(1<<7);
            }

            else
            {
                data&=~(1<<7);
            }

            
        }

        // else even parity
        else
        {
            uint8_t count=0;

            for(uint8_t i=0;i<7;i++)
            {
                if((1<<0)&(data>>i))
                {
                    count++;
                }

            }

            if(count%2!=0)
            {
                data|=(1<<7);
            }

            else
            {
                data&=~(1<<7);
            }
        }
    }

    return data;
    
}

int main() {
    uint8_t data;
    scanf("%hhu", &data);  // 7-bit input

    uint8_t parity_enable, parity_type;
    scanf("%hhu %hhu", &parity_enable, &parity_type);

    UART_Control ctrl;
    ctrl.parity_enable = parity_enable;
    ctrl.parity_type = parity_type;

    uint8_t frame = create_uart_frame(data, &ctrl);
    printf("frame = 0x%02X", frame);

    return 0;
}

Solving Approach

• Count how many 1's in from (0-6)

• for odd parity check If number of 1's is even add 1 at the 7th position else 0.
• for even parity check If number of 1's is odd add 1 at the 7th position else 0.
• else if the parity check if disabled return the same packet