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/* Copyright 2021 QMK
*
* 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/>.
*/
#ifndef __OPTIMIZE__
# pragma message "Compiler optimizations disabled; wait_cpuclock() won't work as designed"
#endif
#define CLOCK_DELAY_NOP8 "nop\n\t nop\n\t nop\n\t nop\n\t nop\n\t nop\n\t nop\n\t nop\n\t"
__attribute__((always_inline)) static inline void wait_cpuclock(unsigned int n) { /* n: 1..135 */
/* The argument n must be a constant expression.
* That way, compiler optimization will remove unnecessary code. */
if (n < 1) {
return;
}
if (n > 8) {
unsigned int n8 = n / 8;
n = n - n8 * 8;
switch (n8) {
case 16:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 15:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 14:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 13:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 12:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 11:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 10:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 9:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 8:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 7:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 6:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 5:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 4:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 3:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 2:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 1:
asm volatile(CLOCK_DELAY_NOP8::: "memory");
case 0:
break;
}
}
switch (n) {
case 8:
asm volatile("nop" ::: "memory");
case 7:
asm volatile("nop" ::: "memory");
case 6:
asm volatile("nop" ::: "memory");
case 5:
asm volatile("nop" ::: "memory");
case 4:
asm volatile("nop" ::: "memory");
case 3:
asm volatile("nop" ::: "memory");
case 2:
asm volatile("nop" ::: "memory");
case 1:
asm volatile("nop" ::: "memory");
case 0:
break;
}
}
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