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Updates to triple buffer

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This commit is contained in:
Fred Sundvik 2016-02-20 23:40:52 +02:00
parent 50edb3d90c
commit 4bb5733cdc
2 changed files with 94 additions and 8 deletions
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54
serial_link/protocol/triple_buffered_object.c
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@ -24,10 +24,60 @@ SOFTWARE.
#include "protocol/triple_buffered_object.h"
#define GET_READ_INDEX() object->state & 3
#define GET_WRITE1_INDEX() (object->state >> 2) & 3
#define GET_WRITE2_INDEX() (object->state >> 4) & 3
#define GET_FREE_INDEX() (object->state >> 6) & 3
#define SET_READ_INDEX(i) object->state = ((object->state & ~3) | i)
#define SET_WRITE1_INDEX(i) object->state = ((object->state & ~(3 << 2)) | (i << 2))
#define SET_WRITE2_INDEX(i) object->state = ((object->state & ~(3 << 4)) | (i << 4))
#define SET_FREE_INDEX(i) object->state = ((object->state & ~(3 << 6)) | (i << 6))
void triple_buffer_init(triple_buffer_object_t* object) {
object->state = 0;
SET_WRITE1_INDEX(0);
SET_WRITE2_INDEX(0);
SET_READ_INDEX(1);
SET_FREE_INDEX(2);
}
static void triple_buffer_begin_read(uint16_t object_size, triple_buffer_object_t* object) {
uint8_t newest = GET_WRITE2_INDEX();
uint8_t free_index = GET_READ_INDEX();
SET_READ_INDEX(newest);
SET_FREE_INDEX(free_index);
}
static void triple_buffer_actual_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) {
uint8_t read_index = GET_READ_INDEX();
memcpy(dst, object->buffer + object_size*read_index, object_size);
}
static void triple_buffer_end_read(uint16_t object_size, triple_buffer_object_t* object) {
}
void triple_buffer_write(uint16_t object_size, triple_buffer_object_t* object, void* src) {
memcpy(object->buffer, src, object_size);
uint8_t write1_index = GET_WRITE1_INDEX();
uint8_t write2_index = GET_WRITE2_INDEX();
uint8_t read_index = GET_READ_INDEX();
uint8_t free_index = GET_FREE_INDEX();
if (write2_index == read_index) {
// We are reading from the other write index
SET_WRITE1_INDEX(free_index);
memcpy(object->buffer + object_size * free_index, src, object_size);
SET_WRITE2_INDEX(free_index);
}
else {
SET_WRITE1_INDEX(write2_index);
memcpy(object->buffer + object_size * write2_index, src, object_size);
SET_WRITE2_INDEX(write2_index);
}
}
void triple_buffer_read(uint16_t object_size, triple_buffer_object_t* object, void* dst) {
memcpy(dst, object->buffer, object_size);
triple_buffer_begin_read(object_size, object);
triple_buffer_actual_read(object_size, object, dst);
triple_buffer_end_read(object_size, object);
}

48
serial_link/tests/triple_buffered_object_tests.c
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@ -25,20 +25,56 @@ SOFTWARE.
#include <cgreen/cgreen.h>
#include "protocol/triple_buffered_object.c"
Describe(TripleBufferedObject);
BeforeEach(TripleBufferedObject) {}
AfterEach(TripleBufferedObject) {}
typedef struct {
uint8_t state;
uint32_t buffer[3];
}test_object_t;
Ensure(TripleBufferedObject, writes_and_and_reads_object) {
test_object_t test_object;
test_object_t test_object;
Describe(TripleBufferedObject);
BeforeEach(TripleBufferedObject) {
triple_buffer_init((triple_buffer_object_t*)&test_object);
}
AfterEach(TripleBufferedObject) {}
Ensure(TripleBufferedObject, writes_and_reads_object) {
uint32_t src = 0x3456ABCC;
uint32_t dst;
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst);
assert_that(dst, is_equal_to(src));
}
Ensure(TripleBufferedObject, writes_and_reads_object_decomposed) {
uint32_t src = 0x3456ABCC;
uint32_t dst;
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
triple_buffer_begin_read(4, (triple_buffer_object_t*)&test_object);
triple_buffer_actual_read(4, (triple_buffer_object_t*)&test_object, &dst);
triple_buffer_end_read(4, (triple_buffer_object_t*)&test_object);
assert_that(dst, is_equal_to(src));
}
Ensure(TripleBufferedObject, writes_twice_and_reads_object) {
uint32_t src = 0x3456ABCC;
uint32_t dst;
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
src = 0x44778899;
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
triple_buffer_read(4, (triple_buffer_object_t*)&test_object, &dst);
assert_that(dst, is_equal_to(src));
}
Ensure(TripleBufferedObject, performs_another_write_in_the_middle_of_read) {
uint32_t src = 1;
uint32_t dst;
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
src = 2;
triple_buffer_begin_read(4, (triple_buffer_object_t*)&test_object);
triple_buffer_write(4, (triple_buffer_object_t*)&test_object, &src);
triple_buffer_actual_read(4, (triple_buffer_object_t*)&test_object, &dst);
triple_buffer_end_read(4, (triple_buffer_object_t*)&test_object);
assert_that(dst, is_equal_to(1));
}