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) {
    int tmp = data & ~(1 << 7);
    int cnt = 0;
    if (ctrl->parity_enable) {
        while (tmp) {
            if (tmp & 0x1)
                cnt++;
            tmp >>= 1;
        }
        if ( ( ctrl->parity_type && !(cnt & 0x1)) ||
             (!ctrl->parity_type &&  (cnt & 0x1)) )
            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