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Bytestuffer recv handling of long frames

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This commit is contained in:
Fred Sundvik 2016-02-14 15:28:57 +02:00
parent eefb5b5634
commit e8cb6d8023
2 changed files with 112 additions and 6 deletions
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20
serial_link/protocol/byte_stuffer.c
View File

@ -24,26 +24,35 @@ SOFTWARE.
#include "protocol/byte_stuffer.h"
#include "protocol/frame_validator.h"
#include <stdio.h>
// This implements the "Consistent overhead byte stuffing protocol"
// https://en.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing
// http://www.stuartcheshire.org/papers/COBSforToN.pdf
#define MAX_FRAME_SIZE 1024
typedef struct byte_stuffer_state {
uint16_t next_zero;
uint16_t data_pos;
uint8_t data[256];
bool long_frame;
uint8_t data[MAX_FRAME_SIZE];
}byte_stuffer_state_t;
void init_byte_stuffer_state(byte_stuffer_state_t* state) {
state->next_zero = 0;
state->data_pos = 0;
state->long_frame = false;
}
static void start_frame(byte_stuffer_state_t* state, uint8_t data) {
}
void recv_byte(byte_stuffer_state_t* state, uint8_t data) {
// Start of a new frame
if (state->next_zero == 0) {
state->next_zero = data;
state->long_frame = data == 0xFF;
state->data_pos = 0;
return;
}
@ -56,16 +65,21 @@ void recv_byte(byte_stuffer_state_t* state, uint8_t data) {
}
else {
// The frame is invalid, so reset
state->next_zero = 0;
state->data_pos = 0;
init_byte_stuffer_state(state);
}
}
else {
if (state->next_zero == 0) {
if (state->long_frame) {
state->next_zero = data;
state->long_frame = data == 0xFF;
}
else {
// Special case for zeroes
state->next_zero = data;
state->data[state->data_pos++] = 0;
}
}
else {
state->data[state->data_pos++] = data;
}

92
serial_link/tests/byte_stuffer_tests.c
View File

@ -154,3 +154,95 @@ Ensure(ByteStuffer, receives_valid_frame_after_unexpected_non_zero) {
recv_byte(&state, 7);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_a_valid_frame_with_over254_non_zeroes_and_then_end_of_frame) {
uint8_t expected[254];
int i;
for (i=0;i<254;i++) {
expected[i] = i + 1;
}
expect(recv_frame,
when(size, is_equal_to(254)),
when(data, is_equal_to_contents_of(expected, 254))
);
recv_byte(&state, 0xFF);
for (i=0;i<254;i++) {
recv_byte(&state, i+1);
}
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_a_valid_frame_with_over254_non_zeroes_next_byte_is_non_zero) {
uint8_t expected[255];
int i;
for (i=0;i<254;i++) {
expected[i] = i + 1;
}
expected[254] = 7;
expect(recv_frame,
when(size, is_equal_to(255)),
when(data, is_equal_to_contents_of(expected, 255))
);
recv_byte(&state, 0xFF);
for (i=0;i<254;i++) {
recv_byte(&state, i+1);
}
recv_byte(&state, 2);
recv_byte(&state, 7);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_a_valid_frame_with_over254_non_zeroes_next_byte_is_zero) {
uint8_t expected[255];
int i;
for (i=0;i<254;i++) {
expected[i] = i + 1;
}
expected[254] = 0;
expect(recv_frame,
when(size, is_equal_to(255)),
when(data, is_equal_to_contents_of(expected, 255))
);
recv_byte(&state, 0xFF);
for (i=0;i<254;i++) {
recv_byte(&state, i+1);
}
recv_byte(&state, 1);
recv_byte(&state, 1);
recv_byte(&state, 0);
}
Ensure(ByteStuffer, receives_two_long_frames_and_some_more) {
uint8_t expected[515];
int i;
int j;
for (j=0;j<2;j++) {
for (i=0;i<254;i++) {
expected[i+254*j] = i + 1;
}
}
for (i=0;i<7;i++) {
expected[254*2+i] = i + 1;
}
expect(recv_frame,
when(size, is_equal_to(515)),
when(data, is_equal_to_contents_of(expected, 510))
);
recv_byte(&state, 0xFF);
for (i=0;i<254;i++) {
recv_byte(&state, i+1);
}
recv_byte(&state, 0xFF);
for (i=0;i<254;i++) {
recv_byte(&state, i+1);
}
recv_byte(&state, 8);
recv_byte(&state, 1);
recv_byte(&state, 2);
recv_byte(&state, 3);
recv_byte(&state, 4);
recv_byte(&state, 5);
recv_byte(&state, 6);
recv_byte(&state, 7);
recv_byte(&state, 0);
}