76. Construct UART Data Frame with Parity Bit

#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) {
    unsigned set_count = 0;
    uint8_t val = data;

    if (ctrl->parity_enable) {
        while (val) {
            set_count += (val & 1U);
            val >>= 1U;
        }

        unsigned is_even = set_count % 2 == 0; 

        if (ctrl->parity_type) {  // odd
            if (is_even) {
                data |= (0x01U << 7);
            }
        } else {  // even
            if (!is_even) {
                data |= (0x01U << 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;
}