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 reg) {
    uint8_t count = 0;
    while (reg) {
        count += (reg & 1);
        reg >>= 1;
    }
    return count;
}

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    data &= 0x7F;
    int parity_bit;
    if (!(ctrl->parity_enable)) {
        return data;
    } else {
        int count = count_ones(data);
        if (ctrl->parity_type) {
            parity_bit = (count % 2) ? 0 : 1;
        } else {
            parity_bit = (count % 2) ? 1 : 0;
        }
    }
    return data | (parity_bit << 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