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;

int count_ones(uint8_t data){
    int count = 0;
    for(int i=0;i<7;i++){
        if(data&0x01){
            count++;
        }
        data >>= 1;
    }
    return count;
}

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    // Your logic here
    if(ctrl->parity_enable == 0){
        return (~(1<<7)) & data;
    }
    
    int ones = count_ones(data);
    int parity_bit;

    if(ctrl->parity_type == 0){
        parity_bit = (ones%2==0) ? 0: 1;
    } else{
        parity_bit = (ones%2==0) ? 1: 0;
    }

    return (parity_bit<<7) | 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

Use . for structures when dealing with copy of value or pass by value(copy)

Use -> for structures when dealing with pass by reference (pointers)