76. Construct UART Data Frame with Parity Bit

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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;
int count_ones(unsigned int bits){
int count=0;
for(int i=0;i<8;i++){
    if(bits&(1<<i))count++;
}
return count;
}
uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    // Your logic here
    data=data&0x7F;
    if(ctrl->parity_enable==0)return data;
    int ones=count_ones(data);
    int parity_bit;
    // the parity_bit + 1s in data should be even 
   if(ctrl->parity_type==0){   
    if(ones%2)//odd    
    parity_bit=1;
    else parity_bit=0;    
   }
   else{
    if(ones%2)parity_bit=0;
    else parity_bit=1;
   }

    return (parity_bit<<7)|data;
}
//           128 64 32 16 8 4 2 1
//           0   0  0   1  1 0 0 1 
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

 

 

 

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