added files for transmitter written in C

RTSP_communication.c

@@ -0,0 +1,110 @@
+/*
+ * RTSP_communication.c
+ *
+ *  Created on: 20.12.2017
+ *      Author: Arkadiusz Bochyñski
+ */
+
+#include "stdlib.h"
+#include "string.h"
+
+#include "RTSP_communication.h"
+#include "crc16.h"
+
+#define START_BYTE				(uint8_t)0xB4		// dop = 0x4B
+#define STOP_BYTE				(uint8_t)0xD2		// dop = 0x2D
+#define CHG_BYTE				(uint8_t)0xA5		// dop = 0x5A
+
+static void (*writeDataFunc)(uint8_t* data, uint8_t size) = NULL;
+
+/* maksymalna iloœc bajtów jaka mo¿e wyst¹pic:
+   8 kana³ów * 4 bajty +
+   2 bajty sumy CRC +
+   1 bajt nbrOfChannels +
+   2 bajty: startu + stopu +
+   wszystkie mo¿liwe bajty change */
+#define MAX_SIZE			69
+
+static uint16_t sendFrame(uint8_t* buffer, uint16_t size)
+{
+	uint8_t frameSize = size + 2;
+	buffer[0] = START_BYTE;
+	buffer[frameSize-1] = STOP_BYTE;
+
+	if( NULL != (*writeDataFunc) )
+	{
+		(*writeDataFunc)(buffer, frameSize);
+
+		return size;
+	}
+	else
+	{
+		return 0;
+	}
+}
+
+static uint8_t preparePayloadAndSend(uint8_t* buffer, uint16_t size)
+{
+	uint8_t* data = malloc(size);
+	memcpy(data, buffer, size);
+	buffer = malloc(MAX_SIZE);
+
+	for(uint8_t k = 0 ; k < size ; k++)
+	{
+		if( (START_BYTE == data[k]) || (STOP_BYTE == data[k]) || (CHG_BYTE == data[k]) )
+		{
+			size++;											// zwiêkszam rozmiar danych o ilosc bajtów CHANGE, ktore zostan¹ dodane
+		}
+	}
+
+	for (uint8_t k = 1, j = 0 ; k < (size+1); k++, j++)		// k = 1, poniewa¿ buffer[0] bêdzie bajtem startu
+	{
+		if( (START_BYTE == data[j]) || (STOP_BYTE == data[j]) || (CHG_BYTE == data[j]) )
+		{
+			buffer[k] = CHG_BYTE;
+			buffer[k+1] = ~data[j];
+			k++;
+		}
+		else
+		{
+			buffer[k] = data[j];
+		}
+	}
+
+	free(data);
+	uint16_t sentAllBytes = sendFrame(buffer, size);
+	free(buffer);
+
+	return sentAllBytes;
+}
+
+uint16_t rtspSendData(void (*writeData)(uint8_t* data, uint8_t size), int* data, uint8_t nbrOfChannels)
+{
+	writeDataFunc = writeData;
+
+	if( nbrOfChannels > 8)
+	{
+		nbrOfChannels = 8;						// max 8 channels, if would be more , then send only first 8
+	}
+
+	uint8_t size = nbrOfChannels * 4 + 3; 		// number of channels * 4 bytes  +  one byte of size + two bytes of checksum
+	uint8_t* buffer = (uint8_t* )malloc(size);
+	*buffer = nbrOfChannels;					// first byte of buffer is number of channels
+
+	for(int i = 0, k = 0; i < nbrOfChannels; i++)
+	{
+		buffer[++k] = (uint8_t)(data[i] >> 24);
+		buffer[++k] = (uint8_t)(data[i] >> 16);
+		buffer[++k] = (uint8_t)(data[i] >> 8);
+		buffer[++k] = (uint8_t) data[i];
+	}
+
+	uint16_t crc = crc16_ccitt((const char* )buffer, size - 2);
+	buffer[size - 2] = crc >> 8;
+	buffer[size - 1] = crc;
+
+	uint16_t sentAllBytes = preparePayloadAndSend(buffer, size);
+	free(buffer);
+
+	return sentAllBytes;
+}

RTSP_communication.h

@@ -0,0 +1,15 @@
+/*
+ * RTSP_communication.h
+ *
+ *  Created on: 20.12.2017
+ *      Author: opetany
+ */
+
+#ifndef INCLUDE_RTSP_COMMUNICATION_H_
+#define INCLUDE_RTSP_COMMUNICATION_H_
+
+#include "stdint.h"
+
+uint16_t rtspSendData(void (*writeData)(uint8_t* data, uint8_t size), int* data, uint8_t nbrOfChannels);
+
+#endif /* INCLUDE_RTSP_COMMUNICATION_H_ */