File content as of revision 0:fc1642aade4a:

/*
 * Set time into RTC
 *
 * Copyright (c) 2019 Kenji Arai / JH1PJL
 *  http://www.page.sannet.ne.jp/kenjia/index.html
 *  http://mbed.org/users/kenjiArai/
 *      Created:    April     27th, 2019
 *      Revised:    June      29th, 2019
 */
 
#include "mbed.h"
 
extern Serial pc;
 
static void chk_and_set_time(char *ptr);
static int32_t  xatoi (char **str, int32_t *res);
static void get_line (char *buff, int len);
 
void time_enter_mode(void)
{
    char *ptr;
    char linebuf[64];
 
    pc.printf("\r\nSet time into RTC\r\n");
    pc.printf(" e.g. >19 6 29 10 11 12 -> June 29th,'19, 10:11:12\r\n");
    pc.printf(" If time is fine, just hit enter\r\n");
    pc.putc('>');
    ptr = linebuf;
    get_line(ptr, sizeof(linebuf));
    pc.printf("\r");
    chk_and_set_time(ptr);
}
 
static void get_line (char *buff, int len)
{
    char c;
    uint32_t idx = 0;
 
    while(true) {
        c = pc.getc();
        if (c == '\r') {
            buff[idx++] = c;
            break;
        }
        if ((c == '\b') && idx) {
            idx--;
            pc.putc(c);
            pc.putc(' ');
            pc.putc(c);
        }
        if (((uint8_t)c >= ' ') && (idx < len - 1)) {
            buff[idx++] = c;
            pc.putc(c);
        }
    }
    buff[idx] = 0;
    pc.puts("\r\n");
}
 
static void chk_and_set_time(char *ptr)
{
    int32_t p1;
    struct tm t;
    time_t seconds;
 
    if (xatoi(&ptr, &p1)) {
        t.tm_year       = (uint8_t)p1 + 100;
        pc.printf("Year:%d ",p1);
        xatoi( &ptr, &p1 );
        t.tm_mon        = (uint8_t)p1 - 1;
        pc.printf("Month:%d ",p1);
        xatoi( &ptr, &p1 );
        t.tm_mday       = (uint8_t)p1;
        pc.printf("Day:%d ",p1);
        xatoi( &ptr, &p1 );
        t.tm_hour       = (uint8_t)p1;
        pc.printf("Hour:%d ",p1);
        xatoi( &ptr, &p1 );
        t.tm_min        = (uint8_t)p1;
        pc.printf("Min:%d ",p1);
        xatoi( &ptr, &p1 );
        t.tm_sec        = (uint8_t)p1;
        pc.printf("Sec: %d \r\n",p1);
    } else {
        return;
    }
    seconds = mktime(&t);
    set_time(seconds);
    pc.printf(
        "Date: %04d/%02d/%02d, %02d:%02d:%02d\r\n",
        t.tm_year + 1900, t.tm_mon + 1, t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec
    );
}
 
static int32_t xatoi (char **str, int32_t *res)
{
    int32_t val;
    uint8_t c, radix, s = 0;
 
    while ((c = **str) == ' ') {
        (*str)++;
    }
    if (c == '-') {
        s = 1;
        c = *(++(*str));
    }
    if (c == '0') {
        c = *(++(*str));
        if (c <= ' ') {
            *res = 0;
            return 1;
        }
        if (c == 'x') {
            radix = 16;
            c = *(++(*str));
        } else {
            if (c == 'b') {
                radix = 2;
                c = *(++(*str));
            } else {
                if ((c >= '0')&&(c <= '9')) {
                    radix = 8;
                } else {
                    return 0;
                }
            }
        }
    } else {
        if ((c < '1')||(c > '9')) {
            return 0;
        }
        radix = 10;
    }
    val = 0;
    while (c > ' ') {
        if (c >= 'a') {
            c -= 0x20;
        }
        c -= '0';
        if (c >= 17) {
            c -= 7;
            if (c <= 9) {
                return 0;
            }
        }
        if (c >= radix) {
            return 0;
        }
        val = val * radix + c;
        c = *(++(*str));
    }
    if (s) {
        val = -val;
    }
    *res = val;
    return 1;
}