Construct UART Data Frame with Parity Bit

Code

#include <stdio.h>
#include <stdint.h>

typedef struct {
    uint8_t parity_enable : 1;  // 1 = use parity
    uint8_t parity_type   : 1;  // 0 = even, 1 = odd
    uint8_t reserved      : 6;
} UART_Control;

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    uint8_t parity;
    if (ctrl->parity_enable) {
        parity = 0;
        for (uint8_t d = data; d; d &= (d - 1))
            parity++;

        parity = (parity & 1) ^ ctrl->parity_type;
        return (parity << 7) | (data & 0x7F);       
    }
    return data & 0x7F;
}

int main() {
    uint8_t data;
    scanf("%hhu", &data);  // 7-bit data (0–127)

    uint8_t parity_enable, parity_type;
    scanf("%hhu %hhu", &parity_enable, &parity_type);  // 0/1 for each

    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\n", frame);

    return 0;
}

Solving Approach