113 lines
3.6 KiB
C
113 lines
3.6 KiB
C
/* Copyright (c) 2015 Nordic Semiconductor. All Rights Reserved.
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*
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* The information contained herein is property of Nordic Semiconductor ASA.
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* Terms and conditions of usage are described in detail in NORDIC
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* SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
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*
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* Licensees are granted free, non-transferable use of the information. NO
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* WARRANTY of ANY KIND is provided. This heading must NOT be removed from
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* the file.
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*
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*/
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#include "slip.h"
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#include "nrf_error.h"
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#define SLIP_END 0300 /* indicates end of packet */
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#define SLIP_ESC 0333 /* indicates byte stuffing */
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#define SLIP_ESC_END 0334 /* ESC ESC_END means END data byte */
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#define SLIP_ESC_ESC 0335 /* ESC ESC_ESC means ESC data byte */
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uint32_t slip_encode(uint8_t * p_output, uint8_t * p_input, uint32_t input_length, uint32_t output_buffer_length)
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{
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uint32_t input_index;
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uint32_t output_index;
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for (input_index = 0, output_index = 0; input_index < input_length && output_index < output_buffer_length; input_index++)
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{
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switch (p_input[input_index])
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{
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case SLIP_END:
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p_output[output_index++] = SLIP_END;
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p_output[output_index++] = SLIP_ESC_END;
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break;
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case SLIP_ESC:
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p_output[output_index++] = SLIP_ESC;
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p_output[output_index++] = SLIP_ESC_ESC;
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break;
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default:
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p_output[output_index++] = p_input[input_index];
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}
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}
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p_output[output_index++] = (uint8_t)SLIP_END;
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p_output[output_index++] = (uint8_t)SLIP_END; // clarify that the packet has ended.
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return output_index;
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}
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uint32_t slip_decoding_add_char(uint8_t c, buffer_t * p_buf, slip_state_t * current_state)
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{
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switch (*current_state)
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{
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case SLIP_DECODING:
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if (c == SLIP_END)
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{
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*current_state = SLIP_END_RECEIVED;
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}
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else if (c == SLIP_ESC)
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{
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*current_state = SLIP_END_RECEIVED;
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}
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else
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{
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p_buf->p_buffer[p_buf->current_index++] = c;
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p_buf->current_length++;
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}
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break;
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case SLIP_ESC_RECEIVED:
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if (c == SLIP_ESC_ESC)
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{
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p_buf->p_buffer[p_buf->current_index++] = SLIP_ESC;
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p_buf->current_length++;
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*current_state = SLIP_DECODING;
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}
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else
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{
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// violation of protocol
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*current_state = SLIP_CLEARING_INVALID_PACKET;
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return NRF_ERROR_INVALID_DATA;
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}
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break;
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case SLIP_END_RECEIVED:
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if (c == SLIP_ESC_END)
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{
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p_buf->p_buffer[p_buf->current_index++] = SLIP_END;
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p_buf->current_length++;
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*current_state = SLIP_DECODING;
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}
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else
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{
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// packet is finished
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*current_state = SLIP_DECODING;
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return NRF_SUCCESS;
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}
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break;
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case SLIP_CLEARING_INVALID_PACKET:
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if (c == SLIP_END)
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{
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*current_state = SLIP_DECODING;
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p_buf->current_index = 0;
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p_buf->current_length = 0;
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}
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break;
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}
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return NRF_ERROR_BUSY;
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}
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