esp-idf/components/freertos/xtensa_init.c

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        XTENSA INITIALIZATION ROUTINES CODED IN C

This file contains miscellaneous Xtensa RTOS-generic initialization functions
that are implemented in C.

*******************************************************************************/


#ifdef XT_BOARD
#include    <xtensa/xtbsp.h>
#endif

#include    "xtensa_rtos.h"

#ifdef XT_RTOS_TIMER_INT

unsigned _xt_tick_divisor = 0;  /* cached number of cycles per tick */

/*
Compute and initialize at run-time the tick divisor (the number of 
processor clock cycles in an RTOS tick, used to set the tick timer).
Called when the processor clock frequency is not known at compile-time.
*/
void _xt_tick_divisor_init(void)
{
#ifdef XT_CLOCK_FREQ

    _xt_tick_divisor = (XT_CLOCK_FREQ / XT_TICK_PER_SEC);

#else

    #ifdef XT_BOARD
    _xt_tick_divisor = xtbsp_clock_freq_hz() / XT_TICK_PER_SEC;
    #else
    #error "No way to obtain processor clock frequency"
    #endif  /* XT_BOARD */

#endif /* XT_CLOCK_FREQ */
}

#endif /* XT_RTOS_TIMER_INT */