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 count_ones(uint8_t data) {
    uint8_t count = 0;

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

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    uint8_t ones;

    // Check parity_enable
    if (ctrl->parity_enable == 0) {
        // Writing data without parity
        return data & ~(1 << 7);
    }
    else {
        // Compute number of ones
        ones = count_ones(data);

        // Check parity_type
        if (ctrl->parity_type) {
            // Odd parity
            if ((ones % 2 == 0) && (ones != 0)) {
                // Even --> 0
                return data & ~(1 << 7);
            }
            else {
                // Odd --> 1
                return data | (1 << 7);
            }
        }
        else {
            // Even parity
            if ((ones % 2 == 0) && (ones != 0)) {
                // Even --> 1
                return data | (1 << 7);
            }
            else {
                // Odd --> 0
                return data & ~(1 << 7);
            }
        }
    }
}

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