pios_inlinedelay.h

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/*
 * 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/>
 *
 * Additional note on redistribution: The copyright and license notices above
 * must be maintained in each individual source file that is a derivative work
 * of this source file; otherwise redistribution is prohibited.
 */

#ifndef _PIOS_INLINEDELAY_H
#define _PIOS_INLINEDELAY_H

#include <pios.h>

static inline void PIOS_INLINEDELAY_AssertClockSpeed()
{
        RCC_ClocksTypeDef clocks;

        RCC_GetClocksFreq(&clocks);
        uint32_t us_ticks = clocks.SYSCLK_Frequency / 1000000;
        PIOS_DEBUG_Assert(us_ticks > 1);

        uint32_t other_us_ticks = PIOS_SYSCLK / 1000000;

        PIOS_Assert(us_ticks = other_us_ticks);
}

static inline uint32_t PIOS_INLINEDELAY_NsToCycles(uint32_t ns)
{
        /* assumptions: integral number of MHz. */

        /* compute the number of system clocks per microsecond */

        uint32_t ticks = PIOS_SYSCLK / 1000;

        ticks <<= 10;           /* 22.10 KHz */

        ticks += 500000;

        ticks /= 1000000;       /* 22.10 GHz */

        ticks *= ns;            /* 22.10 GHz * ns = 22.10 cycles */

        return (ticks + 512) >> 10;
}

static inline uint32_t PIOS_INLINEDELAY_GetCycleCnt()
{
        CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
        return DWT->CYCCNT;
}

static inline void PIOS_INLINEDELAY_TillCycleCnt(uint32_t whence)
{
        uint32_t value;

        /* DWT access should have been enabled to get value already */

        do {
                value = whence - DWT->CYCCNT;
        } while (value < 0xe0000000);           // Windowed against overflow.
}

#endif /* _PIOS_INLINEDELAY_H */