File content as of revision 4:36a4eceb1b7f:

#include "mbed.h"
#include "IothubSerial.h"
#include "crt_abstractions.h"

char* nametemp = "temp";
char* namevolt = "volt";
char* namedeg = "rot";

IothubSerial::IothubSerial()
{
    _hasPending = false;
}

// try to serialize the measurements into the buffer
// return bytes used or -1 if buffer too small or other error
// current serialization is a json array with ',' at end
//  eg: temp: [22.0, 23.1, 22.3],
int IothubSerial::MeasureGroupToString(MeasureGroup& mg, char* buf, int bufsize)
{
    char* name;
    int slen;
    int startlen = bufsize;
    
    switch (mg.MeasId)
    {
        case NM_Temperature:
            name = nametemp;
            break;
            
        case NM_Voltage:
            name = namevolt;
            break;
            
        case NM_Degrees:
            name = namedeg;
            break;
            
        default:
            return -1;
    }
    
    if (bufsize > strlen(name) + 5)
    {
        slen = sprintf_s(buf, bufsize, "\"%s\": [", name);
        if (slen > 0)
        {
            bufsize -= slen;
            buf += slen;
        }
        else
            return -1;
    }
    else
        return -1;
        
    for (int i = 0; i < mg.NumVals; i++)
    {
        if (bufsize > 9)
        {
            if (i < mg.NumVals - 1)
                slen = sprintf_s(buf, bufsize, "%7.2f, ", mg.MeasVals[i]);
            else
                slen = sprintf_s(buf, bufsize, "%7.2f ", mg.MeasVals[i]);
            if (slen > 0)
            {
                bufsize -= slen;
                buf += slen;
            }
            else
                return -1;
        }
        else
            return -1;
    }
    
    if (bufsize > 2)
    {
        slen = sprintf_s(buf, bufsize, "],");
        if (slen > 0)
        {
            bufsize -= slen;
            buf += slen;
        }
        else
            return -1;
    }
    else
        return -1;
        
    return startlen - bufsize;
}

// try to serialize one or more measurements into the buffer
// return bytes used or -1 if buffer too small or other error. 0 if no data
// current serialization is a json object with entry per measure
// eg: { temp: [1, 2], volt: [12.1, 12.2] }
int IothubSerial::MeasureBufToString(char* buf, int bufsize)
{
    int slen;
    bool hasdata = false;
    bool copydata = false;
    int startlen = bufsize;
    
    if (bufsize > 1)
    {
        slen = sprintf_s(buf, bufsize, "{");
        if (slen > 0)
        {
            bufsize -= slen;
            buf += slen;
        }
        else
            return -1;
    }
    else
        return -1;
 
    if (_hasPending)
    {
        hasdata = true;
        slen = MeasureGroupToString(_pending, buf, bufsize);
        if (slen > 0)
        {
            bufsize -= slen;
            buf += slen;
            _hasPending = false;
            copydata = true;
        }
        else
            return -1;          // no room for pending record
    }
    
    while (!MeasureBuf.empty())
    {
        if (!MeasureBuf.pop(_pending))
        {
            break;
        }
        hasdata = true;
        _hasPending = true;
        slen = MeasureGroupToString(_pending, buf, bufsize);
        if (slen > 0)
        {
            bufsize -= slen;
            buf += slen;
            _hasPending = false;
            copydata = true;
        }
        else
            break;              // no room to serialize, leave pending for mext message
    }
    
    if (!hasdata)
        return 0;               // no data
        
    if (!copydata)
        return -1;              // have data but buffer too small

    // replace final ',' with '}'
    *(buf - 1) = '}';

    return startlen - bufsize;
}

bool IothubSerial::HasMeasureGroup()
{
    return _hasPending;
}