/* www.MicroDigitalEd.com
 * p4_5.c C library Console I/O using UART0
 *
 * This program demonstrates the use of C library console I/O.
 * The functions fputc() and fgetc() are implemented using
 * UART0Tx() and UART0Rx() for character I/O.
 * In the fgetc(), the received charater is echoed and if a '\r'
 * is received, it is substituted by a '\n' but both characters are
 * echoed.
 * In fputc() and fgetc(), the file descripter is not checked. All
 * file I/O's are directed to the console.
 *
 * By default the subsystem master clock is 3 MHz.
 * Setting EUSCI_A0->BRW=26 with oversampling disabled yields 115200 Baud.
 *
 * Tested with Keil 5.20 and MSP432 Device Family Pack V2.2.0.
 */

#include "msp.h"
#include <stdio.h>

void UART0_init(void);
unsigned char UART0Rx(void);
int UART0Tx(unsigned char c);

int main(void) {
    int n;
    char str[80];

    UART0_init();

    printf("Test stdio library console I/O functions\r\n");
    fprintf(stdout, "    test for stdout\r\n");
    fprintf(stderr, "    test for stderr\r\n");

    while (1) {
        printf("please enter a number: ");
        scanf("%d", &n);
        printf("the number entered is: %d\r\n", n);
        printf("please type a string: ");
        gets(str);
        printf("the string entered is: ");
        puts(str);
        printf("\r\n");
    }
}

/* initialize UART0 to 115200 Baud at 3 MHz system clock */
void UART0_init(void) {
    EUSCI_A0->CTLW0 |= 1;       /* put in reset mode for config */
    EUSCI_A0->MCTLW = 0;        /* disable oversampling */
    EUSCI_A0->CTLW0 = 0x0081;   /* 1 stop bit, no parity, SMCLK, 8-bit data */
    EUSCI_A0->BRW = 26;         /* 3000000 / 115200 = 26 */
    P1->SEL0 |= 0x0C;           /* P1.3, P1.2 for UART */
    P1->SEL1 &= ~0x0C;
    EUSCI_A0->CTLW0 &= ~1;      /* take UART out of reset mode */
}

/* read a character from UART0 */
unsigned char UART0Rx(void) {
    char c;

    while(!(EUSCI_A0->IFG & 0x01)) ;
    c = EUSCI_A0->RXBUF;
    return c;
}

/* write a character to UART */
int UART0Tx(unsigned char c) {
    while(!(EUSCI_A0->IFG&0x02)) ;
    EUSCI_A0->TXBUF = c;
    return c;
}

/* The code below is the interface to the C standard I/O library.
 * All the I/O are directed to the console, which is UART0.
 */
struct __FILE { int handle; };
FILE __stdin  = {0};
FILE __stdout = {1};
FILE __stderr = {2};

/* Called by C library console/file input
 * This function echoes the character received.
 * If the character is '\r', it is substituted by '\n'.
 */
int fgetc(FILE *f) {
    int c;

    c = UART0Rx();      /* read the character from console */

    if (c == '\r') {    /* if '\r', replace with '\n' */
        UART0Tx(c);     /* echo */
        c = '\n';
    }

    UART0Tx(c);         /* echo */

    return c;
}

/* Called by C library console/file output */
int fputc(int c, FILE *f) {
    return UART0Tx(c);  /* write the character to console */
}