90 lines
3.1 KiB
C
90 lines
3.1 KiB
C
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/* Copyright 2021 QMK
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __OPTIMIZE__
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# pragma message "Compiler optimizations disabled; wait_cpuclock() won't work as designed"
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#endif
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#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"
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__attribute__((always_inline)) static inline void wait_cpuclock(unsigned int n) { /* n: 1..135 */
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/* The argument n must be a constant expression.
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* That way, compiler optimization will remove unnecessary code. */
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if (n < 1) {
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return;
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}
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if (n > 8) {
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unsigned int n8 = n / 8;
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n = n - n8 * 8;
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switch (n8) {
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case 16:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 15:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 14:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 13:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 12:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 11:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 10:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 9:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 8:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 7:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 6:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 5:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 4:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 3:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 2:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 1:
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asm volatile(CLOCK_DELAY_NOP8::: "memory");
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case 0:
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break;
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}
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}
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switch (n) {
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case 8:
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asm volatile("nop" ::: "memory");
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case 7:
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asm volatile("nop" ::: "memory");
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case 6:
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asm volatile("nop" ::: "memory");
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case 5:
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asm volatile("nop" ::: "memory");
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case 4:
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asm volatile("nop" ::: "memory");
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case 3:
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asm volatile("nop" ::: "memory");
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case 2:
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asm volatile("nop" ::: "memory");
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case 1:
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asm volatile("nop" ::: "memory");
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case 0:
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break;
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}
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}
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