From 4bb5733cdca62350c900ce094e1cbbaae59f2246 Mon Sep 17 00:00:00 2001 From: Fred Sundvik Date: Sat, 20 Feb 2016 23:40:52 +0200 Subject: [PATCH] Updates to triple buffer --- serial_link/protocol/triple_buffered_object.c | 54 ++++++++++++++++++- .../tests/triple_buffered_object_tests.c | 48 ++++++++++++++--- 2 files changed, 94 insertions(+), 8 deletions(-) diff --git a/serial_link/protocol/triple_buffered_object.c b/serial_link/protocol/triple_buffered_object.c index f5600364f..a82cef5a6 100644 --- a/serial_link/protocol/triple_buffered_object.c +++ b/serial_link/protocol/triple_buffered_object.c @@ -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); } diff --git a/serial_link/tests/triple_buffered_object_tests.c b/serial_link/tests/triple_buffered_object_tests.c index 66dcefa7f..bf0e3ca67 100644 --- a/serial_link/tests/triple_buffered_object_tests.c +++ b/serial_link/tests/triple_buffered_object_tests.c @@ -25,20 +25,56 @@ SOFTWARE. #include #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)); +}