Construct UART Data Frame with Parity Bit

Code

#include <stdio.h>
#include <stdint.h>
/*
Examples:
Input-> data = 85, parity_enable = 1, parity_type = 0
Output: frame = 0x55 (0101_0101)

what is happening here?
data: 85 (7 bit data) -> (1111 )

----
Input: data = 3, parity_enable = 1, parity_type = 1
Output: frame = 0x83

data: 3 -> 00000011 (2 ones -> parity = 1 -> 1000_0011)
1000_0011 -> 0x83

----
Input: data = 25, parity_enable = 0, parity_type = 0
Output: frame = 0x19

data: 25 -> 1010_1111 -> 0010_1111 -> (4+15) -> 0x19
*/
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;
    data &= 0x7F; // Ensure only 7 bits
    while (data) {
        count += data & 1;
        data >>= 1;
    }
    return count;
}

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    data &= 0x7F; // Only 7 bits
    if (!ctrl->parity_enable) {
        return data; // MSB is 0
    }
    uint8_t ones = count_ones(data);
    uint8_t parity_bit = 0;
    if (ctrl->parity_type == 0) { // Even parity
        parity_bit = (ones % 2) ? 1 : 0;
    } else { // Odd parity
        parity_bit = (ones % 2) ? 0 : 1;
    }
    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