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timing.c
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timing.c
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/*
* This file is part of the Black Magic Debug project.
*
* Copyright (C) 2016 Black Sphere Technologies Ltd.
* Written by Gareth McMullin <gareth@blacksphere.co.nz>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "general.h"
void platform_timeout_set(platform_timeout_s *const t, uint32_t ms)
{
if (ms < SYSTICKMS)
ms = SYSTICKMS;
t->time = platform_time_ms() + ms;
}
bool platform_timeout_is_expired(const platform_timeout_s *const t)
{
/* Cache the current time for the whole calculation */
const uint32_t counter = platform_time_ms();
/*
* Check for the tricky overflow condition and handle that properly -
* when time_ms approaches UINT32_MAX and we try to set a timeout that
* overflows to a low t->time value, if we simply compare with `<`, we will
* erroneously consider the timeout expired for a few ms right at the start of
* the valid interval. Instead, force that region of time to be considered
* not expired by checking the MSb's of the two values and handling that specially.
*/
if ((counter & UINT32_C(0x80000000)) && !(t->time & UINT32_C(0x80000000)))
return false;
return counter > t->time;
}