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/*
* %HEADER%
*
* Simple PWM controller
*
* Copyright (c) 2018-2020 Michael Buesch <m@bues.ch>
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* PWM low frequency / high resolution software interrupt handler */
ISR(TIMER%INDEX%_OVF_vect)
{
uint16_t delay_count;
uint32_t tmp;
/* Calculate the duty-cycle-high time duration.
* The calculated value is a CPU delay loop value and thus
* depends on the CPU frequency. */
memory_barrier();
tmp = pwm.active_setpoint[%INDEX%];
tmp = (tmp * pwm_sp_to_cpucyc_mul(%INDEX%)) / pwm_sp_to_cpucyc_div(%INDEX%);
delay_count = lim_u16(tmp);
port_out_set(%INDEX%, false);
/* Switch the PWM output high, then delay, then switch the output low.
* (It it Ok to delay for a short time in this interrupt). */
if (delay_count == 1u) {
/* 1 clock delay */
__asm__ __volatile__ (
ASM_PWM%INDEX%_OUT_HIGH
ASM_PWM%INDEX%_OUT_LOW
: : ASM_INPUTS
: );
#if FEAT_HIGHRES
} else if (delay_count == 2u) {
#else
} else if (delay_count == 2u || delay_count == 3u) {
#endif
/* 2 clocks delay */
__asm__ __volatile__ (
ASM_PWM%INDEX%_OUT_HIGH
" nop \n"
ASM_PWM%INDEX%_OUT_LOW
: : ASM_INPUTS
: );
#if FEAT_HIGHRES
} else if (delay_count / 3u <= 0xFFu) {
/* 3 clocks per loop iteration
* -> divide count */
uint8_t delay_count8 = (uint8_t)(delay_count / 3u);
if (delay_count > 0u) {
__asm__ __volatile__ (
ASM_PWM%INDEX%_OUT_HIGH
"1: dec %[_delay_count8] \n"
" brne 1b \n"
ASM_PWM%INDEX%_OUT_LOW
: [_delay_count8] "=d" (delay_count8)
: "0" (delay_count8),
ASM_INPUTS
: );
}
#endif /* FEAT_HIGHRES */
} else {
/* 4 clocks per loop iteration
* -> divide count */
delay_count /= 4u;
if (delay_count > 0u) {
__asm__ __volatile__ (
ASM_PWM%INDEX%_OUT_HIGH
"1: sbiw %[_delay_count], 1 \n"
" brne 1b \n"
ASM_PWM%INDEX%_OUT_LOW
: [_delay_count] "=w" (delay_count)
: "0" (delay_count),
ASM_INPUTS
: );
}
}
pwm.irq_count++;
/* We don't want to re-trigger right now,
* just in case the delay took long.
* Clear the interrupt flag. */
pwm_hw_clear_irq_flag(%INDEX%);
memory_barrier();
}
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