Diff: senml_helpers.h

Revision:

0:a9259748d982

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/senml_helpers.h	Sat May 19 17:35:20 2018 +0000
@@ -0,0 +1,167 @@
+/*  _  __  ____    _   _ 
+ * | |/ / |  _ \  | \ | |
+ * | ' /  | |_) | |  \| |
+ * | . \  |  __/  | |\  |
+ * |_|\_\ |_|     |_| \_|
+ * 
+ * (c) 2018 KPN
+ * License: MIT License.
+ * Author: Jan Bogaerts
+ * 
+ * felper functions header
+ */
+
+#ifndef SENMLHELPERS
+#define SENMLHELPERS
+
+#ifdef __MBED__
+    #include "mbed.h"
+    #include "sstream"
+#else
+    #include <stream.h>
+#endif
+#include <senml_enums.h>
+#include <math.h> 
+
+#ifndef SENML_MAX_DOUBLE_PRECISION
+#define SENML_MAX_DOUBLE_PRECISION 4
+#endif // !SENML_MAX_DOUBLE_PRECISION
+
+/** 
+ * Internal helper struct that stores the base value to be used during rendering
+ */
+typedef union BaseData_t{
+    uint64_t baseUint;
+    int64_t baseInt;
+    double baseDouble;
+} BaseData;
+
+/**
+ * Internal helper struct that stores information needed during the rendering process
+ */
+typedef struct SenmlMemoryData_t{
+    char* data;                             //pointer to the buffer that constitutes the input/output buffer
+    int curPos;                             //current position in the buffer.
+    int length;                             //length of the memory buffer.
+} SenmlMemoryData;                          //a record used when the input for the parser or output for the renderer is a data blob stored in memory
+
+/**
+ *  Internal helper struct that stores information needed during the rendering process
+ */
+typedef union SenmlData_t{
+    Stream* stream;
+    SenmlMemoryData blob;
+} SenmlData;                                //choose between input/outpu from a stream object (ex: direct input from uart) or from buffered data.
+
+/**
+ * Internal helper struct that stores information needed during the rendering process
+ */
+typedef struct StreamContext_t{
+    bool dataAsBlob;                        //when true, data is from a memory blob, otherwise it comes from/goes to a stream object (ex: direct from/to uart)
+    SenmlData data;                         //the data source to be parsed or destination to render to. can be from a stream or from data buffered in memory
+    SenMLStreamMethod format;
+    BaseData baseValue;                     //filled in when records need to adjust while rendering data.
+    BaseData baseSum;
+    SenMLDataType baseDataType;             //so we know which data type to use for baseValue and baseSum
+} StreamContext;
+
+/**
+ * Internal data field used for the rendering process.
+ */
+extern StreamContext* _streamCtx;
+
+/** 
+ * Helper function for the generation process
+ * write a double as string to the stream (_streamCtx).
+ * @param f the value to print 
+ * @param digits the nr of digits that should be printed after the comma.
+ */
+void printDouble(double f, unsigned int digits) ;
+
+/**
+ * Helper function for the generation process
+ * convert the data array to base64 string and write to stream (_streamCtx)
+ * @param data pointer to the binary data blob that needs to be rendered as base64 to the stream.
+ * @param length the length of the data blob
+ */
+void printBinaryAsBase64(const unsigned char* data, unsigned int length);
+
+/**
+ * Helper function for the generation process
+ * convert the unit to string and write to stream (_streamCtx).
+ * @param unit the value to write as text to the stream.
+ */
+void printUnit(SenMLUnit unit);
+
+/**
+ * Helper function for the generation process
+ * Writes the specified text to the stream (_streamCtx).
+ * @param value the value to write
+ * @param len the length of the value.
+ */
+void printText(const char*value, int len);
+
+
+
+/**
+ * Helper function for the parsing process
+ * read a character from the current data stream (_streamCtx) 
+ * takes into account that the stream might contain hex values
+ */
+int readChar();
+
+/**
+ * Helper function for the parsing process
+ * peek a character from the current data stream.
+ * takes into account that the stream might contain hex values.
+ */
+int peekChar();
+
+/**
+ * Helper function for the parsing process
+ * flush and reset all input for the current data stream.
+ */
+void flush();
+
+/**
+ * Helper function for the parsing process
+ * Reads the specified nr of characters from the stream (_streamCtx)
+ * takes into account that the stream might contain hex values
+ * @param buffer the buffer to store the values in.
+ * @param len the nr of characters to read from the stream into the buffer. 
+ *        If the input contains hex values, the actual nr of characters read from the
+ *        stream is double this value.
+ */
+inline void readChars(unsigned char* buffer, int len)
+{
+    for(int i = 0; i < len; i++){
+        buffer[i] = readChar();
+    }
+}
+
+/**
+ * Helper function for the parsing process
+ * Checks if there is data available on the stream.
+* Warning: THIS CAN BE PROBLEMATIC ON MBED SYSTEMS>
+ */
+inline bool charAvailable(){
+    if(_streamCtx->dataAsBlob){
+        return _streamCtx->data.blob.curPos < _streamCtx->data.blob.length;
+    }
+    else{
+        #ifdef __MBED__
+            return _streamCtx->data.stream->readable() != 0;      
+        #else  
+            return _streamCtx->data.stream->available() != 0; 
+        #endif
+    }
+}
+
+#endif // SENMLHELPERS
+
+
+
+
+
+
+