初始版本

components/libraries/slip/slip.c

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+/**
+ * Copyright (c) 2015 - 2020, Nordic Semiconductor ASA
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form, except as embedded into a Nordic
+ *    Semiconductor ASA integrated circuit in a product or a software update for
+ *    such product, must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other
+ *    materials provided with the distribution.
+ *
+ * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * 4. This software, with or without modification, must only be used with a
+ *    Nordic Semiconductor ASA integrated circuit.
+ *
+ * 5. Any software provided in binary form under this license must not be reverse
+ *    engineered, decompiled, modified and/or disassembled.
+ *
+ * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+#include "sdk_common.h"
+#if NRF_MODULE_ENABLED(SLIP)
+#include "slip.h"
+
+#include <string.h>
+
+
+#define SLIP_BYTE_END             0300    /* indicates end of packet */
+#define SLIP_BYTE_ESC             0333    /* indicates byte stuffing */
+#define SLIP_BYTE_ESC_END         0334    /* ESC ESC_END means END data byte */
+#define SLIP_BYTE_ESC_ESC         0335    /* ESC ESC_ESC means ESC data byte */
+
+
+ret_code_t slip_encode(uint8_t * p_output,  uint8_t * p_input, uint32_t input_length, uint32_t * p_output_buffer_length)
+{
+    if (p_output == NULL || p_input == NULL || p_output_buffer_length == NULL)
+    {
+        return NRF_ERROR_NULL;
+    }
+
+    *p_output_buffer_length = 0;
+    uint32_t input_index;
+
+    for (input_index = 0; input_index < input_length; input_index++)
+    {
+        switch (p_input[input_index])
+        {
+            case SLIP_BYTE_END:
+                p_output[(*p_output_buffer_length)++] = SLIP_BYTE_ESC;
+                p_output[(*p_output_buffer_length)++] = SLIP_BYTE_ESC_END;
+                break;
+
+            case SLIP_BYTE_ESC:
+                p_output[(*p_output_buffer_length)++] = SLIP_BYTE_ESC;
+                p_output[(*p_output_buffer_length)++] = SLIP_BYTE_ESC_ESC;
+                break;
+
+            default:
+                p_output[(*p_output_buffer_length)++] = p_input[input_index];
+        }
+    }
+    p_output[(*p_output_buffer_length)++] = SLIP_BYTE_END;
+
+    return NRF_SUCCESS;
+}
+
+ret_code_t slip_decode_add_byte(slip_t * p_slip, uint8_t c)
+{
+    if (p_slip == NULL)
+    {
+        return NRF_ERROR_NULL;
+    }
+
+    if (p_slip->current_index == p_slip->buffer_len)
+    {
+        return NRF_ERROR_NO_MEM;
+    }
+
+    switch (p_slip->state)
+    {
+        case SLIP_STATE_DECODING:
+            switch (c)
+            {
+                case SLIP_BYTE_END:
+                    // finished reading packet
+                    return NRF_SUCCESS;
+
+                case SLIP_BYTE_ESC:
+                    // wait for
+                    p_slip->state = SLIP_STATE_ESC_RECEIVED;
+                    break;
+
+                default:
+                    // add byte to buffer
+                    p_slip->p_buffer[p_slip->current_index++] = c;
+                    break;
+            }
+            break;
+
+        case SLIP_STATE_ESC_RECEIVED:
+            switch (c)
+            {
+                case SLIP_BYTE_ESC_END:
+                    p_slip->p_buffer[p_slip->current_index++] = SLIP_BYTE_END;
+                    p_slip->state = SLIP_STATE_DECODING;
+                    break;
+
+                case SLIP_BYTE_ESC_ESC:
+                    p_slip->p_buffer[p_slip->current_index++] = SLIP_BYTE_ESC;
+                    p_slip->state = SLIP_STATE_DECODING;
+                    break;
+
+                default:
+                    // protocol violation
+                    p_slip->state = SLIP_STATE_CLEARING_INVALID_PACKET;
+                    return NRF_ERROR_INVALID_DATA;
+            }
+            break;
+
+        case SLIP_STATE_CLEARING_INVALID_PACKET:
+            if (c == SLIP_BYTE_END)
+            {
+                p_slip->state = SLIP_STATE_DECODING;
+                p_slip->current_index = 0;
+            }
+            break;
+    }
+
+    return NRF_ERROR_BUSY;
+}
+#endif //NRF_MODULE_ENABLED(SLIP)