38 lines
1.4 KiB
C
38 lines
1.4 KiB
C
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/* rtc_get_time_ms.c - get_time_ms implementation using platform RTC.
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* The generic implementation of these functions can be used for architectures
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* or platforms that do not have a more specialized implementation. */
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/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 2008 Free Software Foundation, Inc.
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*
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* GRUB is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GRUB is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <grub/time.h>
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#include <grub/misc.h>
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/* Calculate the time in milliseconds since the epoch based on the RTC. */
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grub_uint64_t
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grub_rtc_get_time_ms (void)
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{
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/* By dimensional analysis:
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1000 ms N rtc ticks 1 s
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------- * ----------- * ----------- = 1000*N/T ms
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1 s 1 T rtc ticks
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*/
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grub_uint64_t ticks_ms_per_sec = ((grub_uint64_t) 1000) * grub_get_rtc ();
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return grub_divmod64 (ticks_ms_per_sec, GRUB_TICKS_PER_SECOND, 0);
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}
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