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Implement receive of valid small byte stuffed frames

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This commit is contained in:
Fred Sundvik 2016-02-14 14:04:51 +02:00
parent 8a991a266e
commit ce3a21cbea
3 changed files with 95 additions and 6 deletions
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36
serial_link/protocol/byte_stuffer.c
View file

@ -25,5 +25,39 @@ SOFTWARE.
#include "protocol/byte_stuffer.h"
#include "protocol/frame_validator.h"
void recv_byte(uint8_t data) {
// This implements the "Consistent overhead byte stuffing protocol"
// https://en.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing
// http://www.stuartcheshire.org/papers/COBSforToN.pdf
typedef struct byte_stuffer_state {
uint16_t next_zero;
uint16_t data_pos;
uint8_t data[256];
}byte_stuffer_state_t;
void init_byte_stuffer_state(byte_stuffer_state_t* state) {
state->next_zero = 0;
state->data_pos = 0;
}
void recv_byte(byte_stuffer_state_t* state, uint8_t data) {
if (state->next_zero == 0) {
state->next_zero = data;
state->data_pos = 0;
return;
}
state->next_zero--;
if (data == 0) {
recv_frame(state->data, state->data_pos);
}
else {
if (state->next_zero == 0) {
state->next_zero = data;
state->data[state->data_pos++] = 0;
}
else {
state->data[state->data_pos++] = data;
}
}
}

4
serial_link/protocol/byte_stuffer.h
View file

@ -22,4 +22,6 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
void recv_byte(uint8_t data);
typedef struct byte_stuffer_state byte_stuffer_state_t;
void init_byte_stuffer_state(byte_stuffer_state_t* state);
void recv_byte(byte_stuffer_state_t* state, uint8_t data);

61
serial_link/tests/byte_stuffer_tests.c
View file

@ -28,8 +28,12 @@ SOFTWARE.
#include "protocol/byte_stuffer.c"
#include "protocol/frame_validator.h"
byte_stuffer_state_t state;
Describe(ByteStuffer);
BeforeEach(ByteStuffer) {}
BeforeEach(ByteStuffer) {
init_byte_stuffer_state(&state);
}
AfterEach(ByteStuffer) {}
void recv_frame(uint8_t* data, uint16_t size) {
@ -38,15 +42,64 @@ void recv_frame(uint8_t* data, uint16_t size) {
Ensure(ByteStuffer, receives_no_frame_for_a_single_zero_byte) {
never_expect(recv_frame);
recv_byte(0);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_no_frame_for_a_single_FF_byte) {
never_expect(recv_frame);
recv_byte(0xFF);
recv_byte(&state, 0xFF);
}
Ensure(ByteStuffer, receives_no_frame_for_a_single_random_byte) {
never_expect(recv_frame);
recv_byte(0x4A);
recv_byte(&state, 0x4A);
}
Ensure(ByteStuffer, receives_single_byte_valid_frame) {
uint8_t expected[] = {0x37};
expect(recv_frame,
when(size, is_equal_to(1)),
when(data, is_equal_to_contents_of(expected, 1))
);
recv_byte(&state, 2);
recv_byte(&state, 0x37);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_three_bytes_valid_frame) {
uint8_t expected[] = {0x37, 0x99, 0xFF};
expect(recv_frame,
when(size, is_equal_to(3)),
when(data, is_equal_to_contents_of(expected, 3))
);
recv_byte(&state, 5);
recv_byte(&state, 0x37);
recv_byte(&state, 0x99);
recv_byte(&state, 0xFF);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_single_zero_valid_frame) {
uint8_t expected[] = {0};
expect(recv_frame,
when(size, is_equal_to(1)),
when(data, is_equal_to_contents_of(expected, 1))
);
recv_byte(&state, 1);
recv_byte(&state, 1);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_valid_frame_with_zeroes) {
uint8_t expected[] = {5, 0, 3, 0};
expect(recv_frame,
when(size, is_equal_to(4)),
when(data, is_equal_to_contents_of(expected, 4))
);
recv_byte(&state, 2);
recv_byte(&state, 5);
recv_byte(&state, 2);
recv_byte(&state, 3);
recv_byte(&state, 1);
recv_byte(&state, 0);
}