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//==========================================================================
//
//      hal_intr.c
//
//      PowerPC interrupt handlers
//
//==========================================================================
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//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    jskov
// Contributors: jskov
// Date:         1999-02-20
// Purpose:      PowerPC interrupt handlers
// Description:  This file contains code to handle interrupt related issues
//               on the PowerPC.
//
//####DESCRIPTIONEND####
//
//==========================================================================
 
#include <pkgconf/hal.h>
 
#include <cyg/hal/hal_intr.h>
 
static unsigned long ticks_per_us;
 
externC void
hal_IRQ_init(void)
{
    // No architecture general initialization, but the variant may have
    // provided some.
    hal_variant_IRQ_init();
 
    // Initialize real-time clock (for delays, etc, even if kernel doesn't use it)
    HAL_CLOCK_INITIALIZE(CYGNUM_HAL_RTC_PERIOD);
 
    // Pre-calculate this factor to avoid the extra calculations on each delay
    ticks_per_us = ((long long)1 * (CYGNUM_HAL_RTC_PERIOD * 100)) / 1000000;
}
 
// Delay for some number of useconds.
externC void 
hal_delay_us(int us)
{
    cyg_int32 old_dec, new_dec;
    long ticks;
    int diff;
 
    // Note: the system constant CYGNUM_HAL_RTC_PERIOD corresponds to 10,000us
    // Scale the desired number of microseconds to be a number of decrementer ticks
    if (ticks_per_us > 0) {
        ticks = us * ticks_per_us;
    } else {
        ticks = ((long long)us * (CYGNUM_HAL_RTC_PERIOD * 100)) / 1000000;
    }
    asm volatile("mfdec  %0;" : "=r"(old_dec) : );
    while (ticks > 0) {
        do {
            asm volatile("mfdec  %0;" : "=r"(new_dec) : );        
        } while (old_dec == new_dec);
        if (new_dec < 0) {
            HAL_CLOCK_RESET(0, CYGNUM_HAL_RTC_PERIOD);
        }
        diff = (old_dec - new_dec);
        if (diff < 1) diff = 1;
        old_dec = new_dec;
        ticks -= diff;
    }
}
 
// -------------------------------------------------------------------------
// EOF hal_intr.c