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Working triple buffering

This commit is contained in:
Fred Sundvik 2016-02-21 01:07:44 +02:00
parent 8e2d70d11f
commit b7059d35f9
4 changed files with 74 additions and 10 deletions

View file

@ -23,6 +23,7 @@ SOFTWARE.
*/ */
#include "protocol/triple_buffered_object.h" #include "protocol/triple_buffered_object.h"
#include "system/system.h"
#define GET_READ_INDEX() object->state & 3 #define GET_READ_INDEX() object->state & 3
#define GET_WRITE_INDEX() (object->state >> 2) & 3 #define GET_WRITE_INDEX() (object->state >> 2) & 3
@ -42,11 +43,21 @@ void triple_buffer_init(triple_buffer_object_t* object) {
SET_DATA_AVAILABLE(0); SET_DATA_AVAILABLE(0);
} }
static void triple_buffer_begin_read(uint16_t object_size, triple_buffer_object_t* object) { static bool triple_buffer_begin_read(uint16_t object_size, triple_buffer_object_t* object) {
uint8_t shared_index = GET_SHARED_INDEX(); serial_link_lock();
uint8_t read_index = GET_READ_INDEX(); if (GET_DATA_AVAILABLE()) {
SET_READ_INDEX(shared_index); uint8_t shared_index = GET_SHARED_INDEX();
SET_SHARED_INDEX(read_index); uint8_t read_index = GET_READ_INDEX();
SET_READ_INDEX(shared_index);
SET_SHARED_INDEX(read_index);
SET_DATA_AVAILABLE(false);
serial_link_unlock();
return true;
}
else {
serial_link_unlock();
return false;
}
} }
static void triple_buffer_actual_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) { static void triple_buffer_actual_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) {
@ -61,13 +72,21 @@ void triple_buffer_write(uint16_t object_size, triple_buffer_object_t* object, v
uint8_t write_index = GET_WRITE_INDEX(); uint8_t write_index = GET_WRITE_INDEX();
memcpy(object->buffer + object_size * write_index, src, object_size); memcpy(object->buffer + object_size * write_index, src, object_size);
serial_link_lock();
uint8_t shared_index = GET_SHARED_INDEX(); uint8_t shared_index = GET_SHARED_INDEX();
SET_SHARED_INDEX(write_index); SET_SHARED_INDEX(write_index);
SET_WRITE_INDEX(shared_index); SET_WRITE_INDEX(shared_index);
SET_DATA_AVAILABLE(true);
serial_link_unlock();
} }
void triple_buffer_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) { bool triple_buffer_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) {
triple_buffer_begin_read(object_size, object); if (triple_buffer_begin_read(object_size, object)) {
triple_buffer_actual_read(object_size, object, dst); triple_buffer_actual_read(object_size, object, dst);
triple_buffer_end_read(object_size, object); triple_buffer_end_read(object_size, object);
return true;
}
else {
return false;
}
} }

View file

@ -30,8 +30,9 @@ typedef struct {
uint8_t buffer[]; uint8_t buffer[];
}triple_buffer_object_t; }triple_buffer_object_t;
void triple_buffer_init(triple_buffer_object_t* object);
void triple_buffer_write(uint16_t object_size, triple_buffer_object_t* object, void* src); void triple_buffer_write(uint16_t object_size, triple_buffer_object_t* object, void* src);
void triple_buffer_read(uint16_t object_size, triple_buffer_object_t* object, void* dst); bool triple_buffer_read(uint16_t object_size, triple_buffer_object_t* object, void* dst);
#endif #endif

View file

@ -0,0 +1,36 @@
/*
The MIT License (MIT)
Copyright (c) 2016 Fred Sundvik
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#ifndef SERIAL_LINK_SYSTEM_H
#define SERIAL_LINK_SYSTEM_H
void serial_link_lock() {
}
void serial_link_unlock() {
}
#endif

View file

@ -47,6 +47,12 @@ Ensure(TripleBufferedObject, writes_and_reads_object) {
assert_that(dst, is_equal_to(src)); assert_that(dst, is_equal_to(src));
} }
Ensure(TripleBufferedObject, does_not_read_empty) {
uint32_t dst;
bool res = triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst);
assert_that(res, is_equal_to(false));
}
Ensure(TripleBufferedObject, writes_and_reads_object_decomposed) { Ensure(TripleBufferedObject, writes_and_reads_object_decomposed) {
uint32_t src = 0x3456ABCC; uint32_t src = 0x3456ABCC;
uint32_t dst; uint32_t dst;
@ -79,6 +85,7 @@ Ensure(TripleBufferedObject, performs_another_write_in_the_middle_of_read) {
assert_that(dst, is_equal_to(1)); assert_that(dst, is_equal_to(1));
triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst); triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst);
assert_that(dst, is_equal_to(2)); assert_that(dst, is_equal_to(2));
assert_that(triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst), is_equal_to(false));
} }
Ensure(TripleBufferedObject, performs_two_writes_in_the_middle_of_read) { Ensure(TripleBufferedObject, performs_two_writes_in_the_middle_of_read) {
@ -95,4 +102,5 @@ Ensure(TripleBufferedObject, performs_two_writes_in_the_middle_of_read) {
assert_that(dst, is_equal_to(1)); assert_that(dst, is_equal_to(1));
triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst); triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst);
assert_that(dst, is_equal_to(3)); assert_that(dst, is_equal_to(3));
assert_that(triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst), is_equal_to(false));
} }