w2

hdlc/hdlc.c

@@ -0,0 +1,261 @@
+#include "hdlc.h"
+
+// HDLC Control field bit positions
+#define HDLC_CONTROL_S_OR_U_FRAME_BIT 0
+#define HDLC_CONTROL_SEND_SEQ_NO_BIT 1
+#define HDLC_CONTROL_S_FRAME_TYPE_BIT 2
+#define HDLC_CONTROL_POLL_BIT 4
+#define HDLC_CONTROL_RECV_SEQ_NO_BIT 5
+
+// HDLC Control type definitions
+#define HDLC_CONTROL_TYPE_RECEIVE_READY 0
+#define HDLC_CONTROL_TYPE_RECEIVE_NOT_READY 1
+#define HDLC_CONTROL_TYPE_REJECT 2
+#define HDLC_CONTROL_TYPE_SELECTIVE_REJECT 3
+
+static hdlc_state_t hdlc_state = {
+        .control_escape = 0,
+        .fcs = FCS_INIT_VALUE,
+        .start_index = -1,
+        .end_index = -1,
+        .src_index = 0,
+        .dest_index = 0,
+};
+
+int hdlc_set_state(hdlc_state_t *state) {
+    if (!state) {
+        return -EINVAL;
+    }
+
+    hdlc_state = *state;
+    return 0;
+}
+
+
+int hdlc_get_state(hdlc_state_t *state) {
+    if (!state) {
+        return -EINVAL;
+    }
+
+    *state = hdlc_state;
+    return 0;
+}
+
+void hdlc_escape_value(char value, char *dest, int *dest_index) {
+    // Check and escape the value if needed
+    if ((value == HDLC_FLAG_SEQUENCE) || (value == HDLC_CONTROL_ESCAPE)) {
+        dest[(*dest_index)++] = HDLC_CONTROL_ESCAPE;
+        value ^= 0x20;
+    }
+
+    // Add the value to the destination buffer and increment destination index
+    dest[(*dest_index)++] = value;
+}
+
+hdlc_control_t hdlc_get_control_type(unsigned char control) {
+    hdlc_control_t value;
+
+    // Check if the frame is a S-frame (or U-frame)
+    if (control & (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT)) {
+        // Check if S-frame type is a Receive Ready (ACK)
+        if (((control >> HDLC_CONTROL_S_FRAME_TYPE_BIT) & 0x3)
+            == HDLC_CONTROL_TYPE_RECEIVE_READY) {
+            value.frame = S_FRAME;
+        } else {
+            // Assume it is an NACK since Receive Not Ready, Selective Reject and U-frames are not supported
+            value.frame = S_FRAME_NACK;
+        }
+
+        // Add the receive sequence number from the S-frame (or U-frame)
+        value.seq_no = (control >> HDLC_CONTROL_RECV_SEQ_NO_BIT);
+    } else {
+        // It must be an I-frame so add the send sequence number (receive sequence number is not used)
+        value.frame = I_FRAME;
+        value.seq_no = (control >> HDLC_CONTROL_SEND_SEQ_NO_BIT);
+    }
+
+    return value;
+}
+
+unsigned char hdlc_frame_control_type(hdlc_control_t *control) {
+    unsigned char value = 0;
+
+    switch (control->frame) {
+        case I_FRAME:
+            // Create the HDLC I-frame control byte with Poll bit set
+            value |= (control->seq_no << HDLC_CONTROL_SEND_SEQ_NO_BIT);
+            value |= (1 << HDLC_CONTROL_POLL_BIT);
+            break;
+        case S_FRAME:
+            // Create the HDLC Receive Ready S-frame control byte with Poll bit cleared
+            value |= (control->seq_no << HDLC_CONTROL_RECV_SEQ_NO_BIT);
+            value |= (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT);
+            break;
+        case S_FRAME_NACK:
+            // Create the HDLC Receive Ready S-frame control byte with Poll bit cleared
+            value |= (control->seq_no << HDLC_CONTROL_RECV_SEQ_NO_BIT);
+            value |= (HDLC_CONTROL_TYPE_REJECT << HDLC_CONTROL_S_FRAME_TYPE_BIT);
+            value |= (1 << HDLC_CONTROL_S_OR_U_FRAME_BIT);
+            break;
+    }
+
+    return value;
+}
+
+void hdlc_get_data_reset() {
+    hdlc_get_data_reset_with_state(&hdlc_state);
+}
+
+void hdlc_get_data_reset_with_state(hdlc_state_t *state) {
+    state->fcs = FCS_INIT_VALUE;
+    state->start_index = state->end_index = -1;
+    state->src_index = state->dest_index = 0;
+    state->control_escape = 0;
+}
+
+//int hdlc_get_data(hdlc_control_t *control, const char *src,
+//                    unsigned int src_len, char *dest, unsigned int *dest_len)
+int hdlc_get_data(hdlc_control_t *control, uint8_t *src,
+                  size_t src_len, uint8_t *dest, size_t *dest_len){
+    return hdlc_get_data_with_state(&hdlc_state, control, src, src_len, dest, dest_len);
+}
+
+//int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, const char *src,
+//                               unsigned int src_len, char *dest, unsigned int *dest_len)
+int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, uint8_t *src,
+                             size_t src_len, uint8_t *dest, size_t *dest_len){
+    int ret;
+    char value;
+    unsigned int i;
+
+    // Make sure that all parameters are valid
+    if (!state || !control || !src || !dest || !dest_len) {
+        return -EINVAL;
+    }
+
+    // Run through the data bytes
+    for (i = 0; i < src_len; i++) {
+        // First find the start flag sequence
+        if (state->start_index < 0) {
+            if (src[i] == HDLC_FLAG_SEQUENCE) {
+                // Check if an additional flag sequence byte is present
+                if ((i < (src_len - 1)) && (src[i + 1] == HDLC_FLAG_SEQUENCE)) {
+                    // Just loop again to silently discard it (accordingly to HDLC)
+                    continue;
+                }
+
+                state->start_index = state->src_index;
+            }
+        } else {
+            // Check for end flag sequence
+            if (src[i] == HDLC_FLAG_SEQUENCE) {
+                // Check if an additional flag sequence byte is present or earlier received
+                if (((i < (src_len - 1)) && (src[i + 1] == HDLC_FLAG_SEQUENCE))
+                    || ((state->start_index + 1) == state->src_index)) {
+                    // Just loop again to silently discard it (accordingly to HDLC)
+                    continue;
+                }
+
+                state->end_index = state->src_index;
+                break;
+            } else if (src[i] == HDLC_CONTROL_ESCAPE) {
+                state->control_escape = 1;
+            } else {
+                // Update the value based on any control escape received
+                if (state->control_escape) {
+                    state->control_escape = 0;
+                    value = src[i] ^ 0x20;
+                } else {
+                    value = src[i];
+                }
+
+                // Now update the FCS value
+                state->fcs = calc_fcs(state->fcs, value);
+
+                if (state->src_index == state->start_index + 2) {
+                    // Control field is the second byte after the start flag sequence
+                    *control = hdlc_get_control_type(value);
+                } else if (state->src_index > (state->start_index + 2)) {
+                    // Start adding the data values after the Control field to the buffer
+                    dest[state->dest_index++] = value;
+                }
+            }
+        }
+        state->src_index++;
+    }
+
+    // Check for invalid frame (no start or end flag sequence)
+    if ((state->start_index < 0) || (state->end_index < 0)) {
+        // Return no message and make sure destination length is 0
+        *dest_len = 0;
+        ret = -ENOMSG;
+    } else {
+        // A frame is at least 4 bytes in size and has a valid FCS value
+        if ((state->end_index < (state->start_index + 4))
+            || (state->fcs != FCS_GOOD_VALUE)) {
+            // Return FCS error and indicate that data up to end flag sequence in buffer should be discarded
+            *dest_len = i;
+            ret = -EIO;
+        } else {
+            // Return success and indicate that data up to end flag sequence in buffer should be discarded
+            *dest_len = state->dest_index - sizeof(state->fcs);
+            ret = i;
+        }
+
+        // Reset values for next frame
+        hdlc_get_data_reset_with_state(state);
+    }
+
+    return ret;
+}
+
+//int hdlc_frame_data(hdlc_control_t *control, const char *src,
+//                      unsigned int src_len, char *dest, unsigned int *dest_len)
+int hdlc_frame_data(hdlc_control_t *control, uint8_t *src,
+                    size_t src_len, uint8_t *dest, size_t *dest_len){
+    unsigned int i;
+    int dest_index = 0;
+    unsigned char value = 0;
+    FCS_SIZE fcs = FCS_INIT_VALUE;
+
+    // Make sure that all parameters are valid
+    if (!control || (!src && (src_len > 0)) || !dest || !dest_len) {
+        return -EINVAL;
+    }
+
+    // Start by adding the start flag sequence
+    dest[dest_index++] = HDLC_FLAG_SEQUENCE;
+
+    // Add the all-station address from HDLC (broadcast)
+    fcs = calc_fcs(fcs, HDLC_ALL_STATION_ADDR);
+    hdlc_escape_value(HDLC_ALL_STATION_ADDR, dest, &dest_index);
+
+    // Add the framed control field value
+    value = hdlc_frame_control_type(control);
+    fcs = calc_fcs(fcs, value);
+    hdlc_escape_value(value, dest, &dest_index);
+
+    // Only DATA frames should contain data
+    if (control->frame == HDLC_FRAME_DATA) {
+        // Calculate FCS and escape data
+        for (i = 0; i < src_len; i++) {
+            fcs = calc_fcs(fcs, src[i]);
+            hdlc_escape_value(src[i], dest, &dest_index);
+        }
+    }
+
+    // Invert the FCS value accordingly to the specification
+    fcs ^= FCS_INVERT_MASK;
+
+    // Run through the FCS bytes and escape the values
+    for (i = 0; i < sizeof(fcs); i++) {
+        value = ((fcs >> (8 * i)) & 0xFF);
+        hdlc_escape_value(value, dest, &dest_index);
+    }
+
+    // Add end flag sequence and update length of frame
+    dest[dest_index++] = HDLC_FLAG_SEQUENCE;
+    *dest_len = dest_index;
+
+    return 0;
+}

hdlc/hdlc.h

@@ -0,0 +1,126 @@
+//
+// Created by 79513 on 15.12.2023.
+//
+
+#ifndef HDLC_H
+#define HDLC_H
+
+#include "fcs.h"
+#include <errno.h>
+#include "stdint.h"
+
+/** HDLC start/end flag sequence */
+#define HDLC_FLAG_SEQUENCE 0x7E
+
+/** HDLC control escape value */
+#define HDLC_CONTROL_ESCAPE 0x7D
+
+/** HDLC all station address */
+#define HDLC_ALL_STATION_ADDR 0xFF
+
+/** Supported HDLC frame types */
+typedef enum {
+    I_FRAME,
+    S_FRAME,
+    S_FRAME_NACK,
+} hdlc_frame_t;
+
+/** Control field information */
+typedef struct {
+    hdlc_frame_t frame;
+    unsigned char seq_no :3;
+} hdlc_control_t;
+
+/** Variables used in hdlc_get_data and hdlc_get_data_with_state
+ * to keep track of received buffers
+ */
+typedef struct {
+    char control_escape;
+    FCS_SIZE fcs;
+    int start_index;
+    int end_index;
+    int src_index;
+    int dest_index;
+} hdlc_state_t;
+
+/**
+ * Set the hdlc state
+ *
+ * @param[in] state The new hdlc state to be used
+ * @retval 0 Success
+ * @retval -EINVAL Invalid parameter
+ */
+int hdlc_set_state(hdlc_state_t *state);
+
+/**
+ * Get current hdlc state
+ *
+ * @param[out] state Current hdlc state
+ * @retval 0 Success
+ * @retval -EINVAL Invalid parameter
+ */
+int hdlc_get_state(hdlc_state_t *state);
+
+/**
+ * Retrieves data from specified buffer containing the HDLC frame. Frames can be
+ * parsed from multiple buffers e.g. when received via UART.
+ *
+ * @param[out] control Control field structure with frame type and sequence number
+ * @param[in] src Source buffer with frame
+ * @param[in] src_len Source buffer length
+ * @param[out] dest Destination buffer (should be able to contain max frame size)
+ * @param[out] dest_len Destination buffer length
+ * @retval >=0 Success (size of returned value should be discarded from source buffer)
+ * @retval -EINVAL Invalid parameter
+ * @retval -ENOMSG Invalid message
+ * @retval -EIO Invalid FCS (size of dest_len should be discarded from source buffer)
+ *
+ * @see hdlc_get_data_with_state
+ */
+int hdlc_get_data(hdlc_control_t *control, uint8_t *src,
+                    size_t src_len, uint8_t *dest, size_t *dest_len);
+
+/**
+ * Retrieves data from specified buffer containing the HDLC frame. Frames can be
+ * parsed from multiple buffers e.g. when received via UART.
+ *
+ * This function is a variation of @ref hdlc_get_data
+ * The difference is only in first argument: hdlc_state_t *state
+ * Data under that pointer is used to keep track of internal buffers.
+ *
+ * @see hdlc_get_data
+ */
+int hdlc_get_data_with_state(hdlc_state_t *state, hdlc_control_t *control, uint8_t *src,
+                             size_t src_len, uint8_t *dest, size_t *dest_len);
+
+/**
+ * Resets values used in yahdlc_get_data function to keep track of received buffers
+ */
+void hdlc_get_data_reset();
+
+/**
+ * This is a variation of @ref hdlc_get_data_reset
+ * Resets state values that are under the pointer provided as argument
+ *
+ * This function need to be called before the first call to hdlc_get_data_with_state
+ * when custom state storage is used.
+ *
+ * @see hdlc_get_data_reset
+ */
+void hdlc_get_data_reset_with_state(hdlc_state_t *state);
+
+/**
+ * Creates HDLC frame with specified data buffer.
+ *
+ * @param[in] control Control field structure with frame type and sequence number
+ * @param[in] src Source buffer with data
+ * @param[in] src_len Source buffer length
+ * @param[out] dest Destination buffer (should be bigger than source buffer)
+ * @param[out] dest_len Destination buffer length
+ * @retval 0 Success
+ * @retval -EINVAL Invalid parameter
+ */
+int hdlc_frame_data(hdlc_control_t *control, uint8_t *src,
+                      size_t src_len, uint8_t *dest, size_t *dest_len);
+
+#endif //HDLC_H

hdlc/main.c

@@ -0,0 +1,154 @@
+//#include "hdlc.h"
+#include "stdio.h"
+#include "client.h"
+#include <stdlib.h>
+#include <inttypes.h>
+
+int main(){
+    struct Client hdlc;
+    connect(&hdlc);
+    uint8_t frame_data[8];
+    get_frame(&hdlc, frame_data, sizeof(frame_data), 0, 0);
+
+    hdlc_get_raw_data(&hdlc, frame_data, sizeof(frame_data));
+
+    uint8_t send[64];
+    uint8_t buffer[134];
+    for (int i = 0; i < sizeof(send); i++) {
+        send[i] = (uint8_t) (rand() % 0x70);
+    }
+    send_data(&hdlc, send, sizeof(send_data));
+    //get_frame(&hdlc, buffer, sizeof(buffer), send_data, sizeof(send_data));
+
+    hdlc_get_raw_data(&hdlc, buffer, sizeof(buffer));
+
+    // test 1
+
+//    int ret;
+//    uint8_t frame_data[8], recv_data[8];
+//    size_t i, frame_length = 0, recv_length = 0;
+//    hdlc_control_t control_send, control_recv;
+
+//    // Run through the supported sequence numbers (3-bit)
+//    for (i = 0; i <= 7; i++) {
+//        // Initialize the control field structure with frame type and sequence number
+//        control_send.frame = HDLC_FRAME_ACK;
+//        control_send.seq_no = i;
+//
+//        // Create an empty frame with the control field information
+//        ret = hdlc_frame_data(&control_send, NULL, 0, frame_data, &frame_length);
+//
+//        // Get the data from the frame
+//        ret = hdlc_get_data(&control_recv, frame_data, frame_length, recv_data,
+//                              &recv_length);
+//
+//        // Result should be frame_length minus start flag to be discarded and no bytes received
+//        if(ret != (int )frame_length - 1){
+//            printf("err");
+//        }
+//    }
+//    if (recv_length != 0){
+//        printf("err2");
+//    }
+//
+//    if (control_send.frame != control_recv.frame){
+//        printf("err3");
+//    }
+//
+//    if (control_send.seq_no != control_recv.seq_no){
+//        printf("err4");
+//    }
+
+    // test 2
+
+    // Run through the supported sequence numbers (3-bit)
+//    for (i = 0; i <= 7; i++) {
+//        // Initialize the control field structure with frame type and sequence number
+//        control_send.frame = HDLC_FRAME_DATA;
+//        control_send.seq_no = i;
+//
+//        char* input = "311";
+//        uint8_t data = (uint8_t)atoi(input);
+//
+//        // Create an empty frame with the control field information
+//        ret = hdlc_frame_data(&control_send, &data, 3, frame_data, &frame_length);
+//        if (ret != 0){
+//            printf("err123\n");
+//        }
+//
+//        // Get the data from the frame
+//        ret = hdlc_get_data(&control_recv, frame_data, frame_length, recv_data,
+//                            &recv_length);
+//
+//        // Result should be frame_length minus start flag to be discarded and no bytes received
+//        if(ret != (int )frame_length - 1){
+//            printf("err333\n");
+//        }
+//        if (recv_length != 0){
+//            printf("err2\n");
+//        }
+//
+//        // Verify the control field information
+//        if (control_send.frame != control_recv.frame){
+//            printf("err3\n");
+//        }
+//
+//        if (control_send.seq_no != control_recv.seq_no){
+//            printf("err4\n");
+//        }
+//    }
+
+//    int ret;
+//    hdlc_control_t control;
+//    uint8_t send_data[512], frame_data[530], recv_data[530];
+//    size_t i, frame_length = 0, recv_length = 0, buf_length = 16;
+//
+//    // Initialize data to be send with random values (up to 0x70 to keep below the values to be escaped)
+//    for (i = 0; i < sizeof(send_data); i++) {
+//        send_data[i] = (uint8_t) (rand() % 0x70);
+//    }
+//
+//    // Initialize control field structure and create frame
+//    control.frame = HDLC_FRAME_DATA;
+//    ret = hdlc_frame_data(&control, send_data, sizeof(send_data), frame_data,
+//                            &frame_length);
+//
+//    // Check that frame length is maximum 2 bytes larger than data due to escape of FCS value
+//    if(frame_length >= ((sizeof(send_data) + 6) + 2)){
+//        printf("1");
+//    }
+//    if(ret != 0){
+//        printf("2");
+//    }
+//
+//    // Run though the different buffers (simulating decode of buffers from UART)
+//    for (i = 0; i <= sizeof(send_data); i += buf_length) {
+//        // Decode the data
+//        ret = hdlc_get_data(&control, &frame_data[i], buf_length, recv_data,
+//                              &recv_length);
+//
+//        printf("%zu: %s\n", i, recv_data);
+//
+//        if (i < sizeof(send_data)) {
+//            // All chunks until the last should return no message and zero length
+//            if (ret != -ENOMSG){
+//                printf("3");
+//            }
+//            if (recv_length != 0){
+//                printf("1231");
+//            }
+//        } else {
+//            if (ret > 7){
+//                printf("332");
+//            }
+//            if (recv_length != sizeof(send_data)){
+//                printf("88888");
+//            }
+//            // The last chunk should return max 6 frame bytes - 1 start flag sequence byte + 2 byte for the possible
+//            // escaped FCS = 7 bytes
+////            BOOST_CHECK(ret <= 7);
+////            BOOST_CHECK_EQUAL(recv_length, sizeof(send_data));
+//            //printf("5");
+//        }
+//    }
+}