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) {
    uint8_t frame = 0;

    if (ctrl->parity_enable == 0) {
        // Parity disabled: MSB = 0, lower 7 bits = data
        frame = data & 0x7F; // mask to 7 bits
    } else {
        // Parity enabled
        uint8_t ones = 0;
        uint8_t temp = data & 0x7F; // ensure only 7 bits

        // Count number of 1s in the 7-bit data
        for (int i = 0; i < 7; i++) {
            if (temp & (1 << i)) {
                ones++;
            }
        }

        uint8_t parity_bit;
        if (ctrl->parity_type == 0) {
            // Even parity
            parity_bit = (ones % 2 == 0) ? 0 : 1;
        } else {
            // Odd parity
            parity_bit = (ones % 2 == 0) ? 1 : 0;
        }

        // Place parity bit in MSB, data in lower 7 bits
        frame = (parity_bit << 7) | temp;
    }

    return frame;
}

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