75 lines
2.8 KiB
C
75 lines
2.8 KiB
C
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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2021 Jim Mussared
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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// This is a translation of the cycle counter implementation in ports/stm32/machine_bitstream.c.
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#include "py/mpconfig.h"
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#include "py/mphal.h"
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#include "hardware/structs/systick.h"
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#if MICROPY_PY_MACHINE_BITSTREAM
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#define MP_HAL_BITSTREAM_NS_OVERHEAD (9)
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void __time_critical_func(machine_bitstream_high_low)(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const uint8_t *buf, size_t len) {
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uint32_t fcpu_mhz = mp_hal_get_cpu_freq() / 1000000;
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// Convert ns to clock ticks [high_time_0, period_0, high_time_1, period_1].
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for (size_t i = 0; i < 4; ++i) {
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timing_ns[i] = fcpu_mhz * timing_ns[i] / 1000;
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if (timing_ns[i] > (2 * MP_HAL_BITSTREAM_NS_OVERHEAD)) {
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timing_ns[i] -= MP_HAL_BITSTREAM_NS_OVERHEAD;
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}
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if (i % 2 == 1) {
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// Convert low_time to period (i.e. add high_time).
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timing_ns[i] += timing_ns[i - 1] - MP_HAL_BITSTREAM_NS_OVERHEAD;
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}
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}
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mp_hal_pin_output(pin);
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// Enable the systick counter, source CPU clock.
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systick_hw->csr = 5;
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uint32_t irq_state = mp_hal_quiet_timing_enter();
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for (size_t i = 0; i < len; ++i) {
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uint8_t b = buf[i];
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for (size_t j = 0; j < 8; ++j) {
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uint32_t *t = &timing_ns[b >> 6 & 2];
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uint32_t start_ticks = systick_hw->cvr = SYSTICK_MAX;
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mp_hal_pin_high(pin);
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while ((start_ticks - systick_hw->cvr) < t[0]) {
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}
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b <<= 1;
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mp_hal_pin_low(pin);
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while ((start_ticks - systick_hw->cvr) < t[1]) {
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}
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}
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}
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mp_hal_quiet_timing_exit(irq_state);
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}
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#endif // MICROPY_PY_MACHINE_BITSTREAM
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