1 #include <stdio.h> 2 3 #define MASK_RXCIE 0x80 4 #define MASK_TXCIE 0x40 5 #define MASK_UDRIE 0x20 6 #define MASK_RXEN 0x10 7 #define MASK_TXEN 0x08 8 #define MASK_CHR9 0x04 9 #define MASK_RXB8 0x02 10 #define MASK_TXB8 0x01 11 12 #define SHIFT_RXCIE 7 13 #define SHIFT_TXCIE 6 14 #define SHIFT_UDRIE 5 15 #define SHIFT_RXEN 4 16 #define SHIFT_TXEN 3 17 #define SHIFT_CHR9 2 18 #define SHIFT_RXB8 1 19 #define SHIFT_TXB8 0 20 21 #define MSG_TX_COMPLETE "Transmission Completed" 22 #define MSG_TX_UNCOMPLETE "Transmission Incomplete" 23 24 typedef unsigned char uchar; 25 typedef enum { LO, HI } bit_t; 26 typedef enum { FALSE, TRUE } bool_t; 27 typedef enum { 28 OK, 29 ERROR_TRANSMISSION_UNCOMPLETE, 30 ERROR_NULL_POINTER 31 } status_t; 32 33 bit_t tx_complete(uchar); 34 status_t tx_complete2(uchar, bit_t *state); 35 36 void print_reg(uchar reg) 37 { 38 for(size_t i = ((sizeof(reg) * 8)); i > 0; i--) 39 putchar((reg & (0x01 << (i - 1))) ? '1' : '0'); 40 41 putchar('\n'); 42 } 43 44 int main (void) 45 { 46 uchar reg = 0x42; 47 status_t st; 48 bit_t tx; 49 50 print_reg(reg); 51 52 printf("%s\n", tx_complete(reg) ? MSG_TX_UNCOMPLETE : MSG_TX_COMPLETE); 53 54 if((st = tx_complete2(reg, &tx))) return st; 55 printf("%s\n", tx ? MSG_TX_COMPLETE : MSG_TX_UNCOMPLETE); 56 57 return OK; 58 } 59 60 bit_t tx_complete(uchar reg) 61 { 62 return ((reg & MASK_TXCIE) >> SHIFT_TXCIE) ? LO : HI; 63 } 64 65 status_t tx_complete2(uchar reg, bit_t *state) 66 { 67 if(!state) return ERROR_NULL_POINTER; 68 69 *state = ((reg & MASK_TXCIE) >> SHIFT_TXCIE); 70 71 return OK; 72 }
