Proper RTC emulation based on work by Mahod.
Updated README.md. Updated AMD makefile.
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OBattler
261
src/rtc.c
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261
src/rtc.c
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/* Emulation of:
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Dallas Semiconductor DS12C887 Real Time Clock
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http://datasheets.maximintegrated.com/en/ds/DS12885-DS12C887A.pdf
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http://dev-docs.atariforge.org/files/MC146818A_RTC_1984.pdf
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "nvr.h"
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#include "rtc.h"
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int enable_sync;
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typedef struct
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{
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int sec;
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int min;
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int hour;
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int mday;
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int mon;
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int year;
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}
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internal_clock_t;
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internal_clock_t internal_clock;
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/* When the RTC was last updated */
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time_t rtc_set_time = 0;
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/* Table for days in each month */
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int rtc_days_in_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
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/* Called to determine whether the year is leap or not */
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static int rtc_is_leap(int org_year)
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{
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if (org_year % 400 == 0) return 1;
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if (org_year % 100 == 0) return 0;
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if (org_year % 4 == 0) return 1;
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return 0;
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}
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/* Called to determine the days in the current month */
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static int rtc_get_days(int org_month, int org_year)
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{
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if (org_month != 2)
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{
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return rtc_days_in_month[org_month];
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}
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else
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{
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return rtc_is_leap(org_year) ? 29 : 28;
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}
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}
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/* Called when the internal clock gets updated */
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static void rtc_recalc()
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{
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if (internal_clock.sec == 60)
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{
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internal_clock.sec = 0;
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internal_clock.min++;
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}
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if (internal_clock.min == 60)
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{
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internal_clock.min = 0;
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internal_clock.hour++;
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}
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if (internal_clock.hour == 24)
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{
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internal_clock.hour = 0;
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internal_clock.mday++;
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}
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if (internal_clock.mday == (rtc_get_days(internal_clock.mon, internal_clock.year) + 1))
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{
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internal_clock.mday = 1;
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internal_clock.mon++;
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}
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if (internal_clock.mon == 13)
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{
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internal_clock.mon = 1;
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internal_clock.year++;
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}
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nvr_dosave = 1;
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}
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/* Called when ticking the second */
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void rtc_tick()
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{
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internal_clock.sec++;
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rtc_recalc();
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}
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/* Called when modifying the NVR registers */
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void time_update(char *nvrram, int reg)
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{
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int temp;
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switch(reg)
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{
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case RTCSECONDS:
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internal_clock.sec = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCSECONDS] : DCB(nvrram[RTCSECONDS]);
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break;
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case RTCMINUTES:
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internal_clock.min = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCMINUTES] : DCB(nvrram[RTCMINUTES]);
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break;
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case RTCHOURS:
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temp = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCHOURS] : DCB(nvrram[RTCHOURS]);
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if (nvrram[RTCREGB] & RTC2412)
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{
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internal_clock.hour = temp;
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}
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else
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{
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internal_clock.hour = ((temp & ~RTCAMPM) % 12) + ((temp & RTCAMPM) ? 12 : 0);
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}
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break;
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case RTCDOM:
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internal_clock.mday = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCDOM] : DCB(nvrram[RTCDOM]);
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break;
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case RTCMONTH:
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internal_clock.mon = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCMONTH] : DCB(nvrram[RTCMONTH]);
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break;
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case RTCYEAR:
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internal_clock.year = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCYEAR] : DCB(nvrram[RTCYEAR]);
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internal_clock.year += (nvrram[RTCREGB] & RTCDM) ? 1900 : (DCB(nvrram[RTCCENTURY]) * 100);
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break;
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case RTCCENTURY:
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if (nvrram[RTCREGB] & RTCDM) return;
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internal_clock.year %= 100;
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internal_clock.year += (DCB(nvrram[RTCCENTURY]) * 100);
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break;
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case 0xFF: /* Load the entire internal clock state from the NVR. */
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internal_clock.sec = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCSECONDS] : DCB(nvrram[RTCSECONDS]);
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internal_clock.min = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCMINUTES] : DCB(nvrram[RTCMINUTES]);
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temp = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCHOURS] : DCB(nvrram[RTCHOURS]);
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if (nvrram[RTCREGB] & RTC2412)
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{
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internal_clock.hour = temp;
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}
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else
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{
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internal_clock.hour = ((temp & ~RTCAMPM) % 12) + ((temp & RTCAMPM) ? 12 : 0);
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}
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internal_clock.mday = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCDOM] : DCB(nvrram[RTCDOM]);
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internal_clock.mon = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCMONTH] : DCB(nvrram[RTCMONTH]);
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internal_clock.year = (nvrram[RTCREGB] & RTCDM) ? nvrram[RTCYEAR] : DCB(nvrram[RTCYEAR]);
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internal_clock.year += (nvrram[RTCREGB] & RTCDM) ? 1900 : (DCB(nvrram[RTCCENTURY]) * 100);
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break;
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}
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}
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/* Called to obtain the current day of the week based on the internal clock */
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static int time_week_day()
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{
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int day_of_month = internal_clock.mday;
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int month2 = internal_clock.mon;
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int year2 = internal_clock.year % 100;
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int century = ((internal_clock.year - year2) / 100) % 4;
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int sum = day_of_month + month2 + year2 + century;
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/* (Sum mod 7) gives 0 for Saturday, we need it for Sunday, so +6 for Saturday to get 6 and Sunday 0 */
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int raw_wd = ((sum + 6) % 7);
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return raw_wd;
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}
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/* Called to get time into the internal clock */
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static void time_internal(struct tm **time_var)
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{
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if (*time_var == NULL) *time_var = (struct tm *) malloc(sizeof(struct tm));
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(*time_var)->tm_sec = internal_clock.sec;
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(*time_var)->tm_min = internal_clock.min;
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(*time_var)->tm_hour = internal_clock.hour;
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(*time_var)->tm_wday = time_week_day();
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(*time_var)->tm_mday = internal_clock.mday;
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(*time_var)->tm_mon = internal_clock.mon - 1;
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(*time_var)->tm_year = internal_clock.year - 1900;
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}
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/* Periodic RTC update function
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See also: nvr_onesec() in nvr.c
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*/
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void time_get(char *nvrram)
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{
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time_t cur_time;
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struct tm* cur_time_tm;
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int dow, mon, year;
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if (enable_sync)
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{
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cur_time = time(NULL);
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/* Mingw doesn't support localtime_r */
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#if __MINGW32__
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cur_time_tm = localtime(&cur_time);
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#else
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#if __MINGW64__
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cur_time_tm = localtime(&cur_time);
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#else
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localtime_r(&cur_time, &cur_time_tm);
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#endif
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#endif
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}
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else
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{
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time_internal(&cur_time_tm);
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}
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if (nvrram[RTCREGB] & RTCDM)
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{
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nvrram[RTCSECONDS] = cur_time_tm->tm_sec;
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nvrram[RTCMINUTES] = cur_time_tm->tm_min;
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nvrram[RTCDOW] = cur_time_tm->tm_wday + 1;
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nvrram[RTCDOM] = cur_time_tm->tm_mday;
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nvrram[RTCMONTH] = cur_time_tm->tm_mon + 1;
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nvrram[RTCYEAR] = cur_time_tm->tm_year % 100;
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if (nvrram[RTCREGB] & RTC2412)
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{
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nvrram[RTCHOURS] = cur_time_tm->tm_hour;
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}
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else
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{
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nvrram[RTCHOURS] = (cur_time_tm->tm_hour % 12) ? (cur_time_tm->tm_hour % 12) : 12;
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if (cur_time_tm->tm_hour > 11)
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{
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nvrram[RTCHOURS] |= RTCAMPM;
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}
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}
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}
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else
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{
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nvrram[RTCSECONDS] = BCD(cur_time_tm->tm_sec);
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nvrram[RTCMINUTES] = BCD(cur_time_tm->tm_min);
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nvrram[RTCDOW] = BCD(cur_time_tm->tm_wday + 1);
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nvrram[RTCDOM] = BCD(cur_time_tm->tm_mday);
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nvrram[RTCMONTH] = BCD(cur_time_tm->tm_mon + 1);
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nvrram[RTCYEAR] = BCD(cur_time_tm->tm_year % 100);
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if (nvrram[RTCREGB] & RTC2412)
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{
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nvrram[RTCHOURS] = BCD(cur_time_tm->tm_hour);
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}
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else
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{
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nvrram[RTCHOURS] = (cur_time_tm->tm_hour % 12) ? BCD(cur_time_tm->tm_hour % 12) : BCD(12);
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if (cur_time_tm->tm_hour > 11)
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{
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nvrram[RTCHOURS] |= RTCAMPM;
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}
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}
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}
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}
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