79 lines
2.9 KiB
C
79 lines
2.9 KiB
C
/*
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The MIT License (MIT)
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Copyright (c) 2016 Fred Sundvik
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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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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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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 THE
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SOFTWARE.
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*/
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#include "serial_link/protocol/triple_buffered_object.h"
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#include "serial_link/system/serial_link.h"
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#include <stdbool.h>
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#include <stddef.h>
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#define GET_READ_INDEX() object->state & 3
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#define GET_WRITE_INDEX() (object->state >> 2) & 3
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#define GET_SHARED_INDEX() (object->state >> 4) & 3
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#define GET_DATA_AVAILABLE() (object->state >> 6) & 1
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#define SET_READ_INDEX(i) object->state = ((object->state & ~3) | i)
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#define SET_WRITE_INDEX(i) object->state = ((object->state & ~(3 << 2)) | (i << 2))
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#define SET_SHARED_INDEX(i) object->state = ((object->state & ~(3 << 4)) | (i << 4))
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#define SET_DATA_AVAILABLE(i) object->state = ((object->state & ~(1 << 6)) | (i << 6))
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void triple_buffer_init(triple_buffer_object_t* object) {
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object->state = 0;
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SET_WRITE_INDEX(0);
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SET_READ_INDEX(1);
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SET_SHARED_INDEX(2);
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SET_DATA_AVAILABLE(0);
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}
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void* triple_buffer_read_internal(uint16_t object_size, triple_buffer_object_t* object) {
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serial_link_lock();
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if (GET_DATA_AVAILABLE()) {
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uint8_t shared_index = GET_SHARED_INDEX();
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uint8_t read_index = GET_READ_INDEX();
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SET_READ_INDEX(shared_index);
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SET_SHARED_INDEX(read_index);
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SET_DATA_AVAILABLE(false);
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serial_link_unlock();
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return object->buffer + object_size * shared_index;
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}
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else {
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serial_link_unlock();
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return NULL;
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}
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}
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void* triple_buffer_begin_write_internal(uint16_t object_size, triple_buffer_object_t* object) {
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uint8_t write_index = GET_WRITE_INDEX();
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return object->buffer + object_size * write_index;
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}
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void triple_buffer_end_write_internal(triple_buffer_object_t* object) {
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serial_link_lock();
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uint8_t shared_index = GET_SHARED_INDEX();
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uint8_t write_index = GET_WRITE_INDEX();
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SET_SHARED_INDEX(write_index);
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SET_WRITE_INDEX(shared_index);
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SET_DATA_AVAILABLE(true);
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serial_link_unlock();
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}
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