Char* and Byte conversion causing issue while compilation

[khawajamechatronics]

Is there any specific reason of using Byte* at some point and char* at some point ?

isnt better to use single type though out all the messages?

[khawajamechatronics]

Need to change
#define TX 0x03 // Transmit what is in FIFO queue
to
#define TXRF 0x03 // Transmit what is in FIFO queue
as TX defination conflicts on some platforms defines.
similarly
#define RX 0x05 // Receive mode in OOK/FSK configuration
to
#define RXRF 0x05 // Receive mode in OOK/FSK configuration

also
byte PWR;
change this to
byte PWRRF;

[danieledenaro]

About byte and char:
substantially LoRa transmits and receives bytes. So buffers are in bytes format. But to semplify use, I create functions that accept null terminated string (i.e. chars). This is the reason for some casting operations.

Define value names:
ok. Thanks for warning about conflict names with others libraries.

[khawajamechatronics]

Problem is Byte and Char holds same 8 bit data, but Byte is Unsigned Char, and Char is Signed Char, so compilation occurs in some platform (using with STM32) as it cannot do type casting, I think its better to use Char instead of Byte if all the data is positive or non negative.

[khawajamechatronics]

I am getting these errors

`

lib/LoraNode/src/LoraNode.cpp: In member function 'void LoraNode::changeMessageBufferLen(int)':
lib/LoraNode/src/LoraNode.cpp:130:11: error: invalid conversion from 'char*' to 'byte* {aka unsigned char*}' [-fpermissive]
recbuff=new char[bufflen];
^
lib/LoraNode/src/LoraNode.cpp: In member function 'bool LoraNode::incomingMessage(int, int)':
lib/LoraNode/src/LoraNode.cpp:187:41: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
if (LR.sendNetMess(sender,NODEADD,"AK")<0) {return false;}
^
lib/LoraNode/src/LoraNode.cpp: In member function 'bool LoraNode::writeMessageByte(int, byte*, int, int)':
lib/LoraNode/src/LoraNode.cpp:197:42: error: invalid conversion from 'byte* {aka unsigned char*}' to 'char*' [-fpermissive]
if (LR.sendNetMess(dest,NODEADD,message)<0) {return false;}
^
In file included from lib/LoraNode/src/LoraNode.h:47:0,
from lib/LoraNode/src/LoraNode.cpp:2:
lib/LoraNode/src/LORA.h:97:7: note: initializing argument 3 of 'int LORA::sendNetMess(unsigned int, unsigned int, char*)'
int sendNetMess(unsigned int toSubAdd, unsigned int fromSubAdd, char* mess);
^
lib/LoraNode/src/LoraNode.cpp: In member function 'bool LoraNode::newMessByteAvailable(int, byte*, int, int)':
lib/LoraNode/src/LoraNode.cpp:215:41: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
if (LR.sendNetMess(sender,NODEADD,"AK")<0) {return false;}
^
lib/LoraNode/src/LoraNode.cpp: In member function 'byte* LoraNode::getMessageByte()':
lib/LoraNode/src/LoraNode.cpp:219:54: error: invalid conversion from 'char*' to 'byte* {aka unsigned char*}' [-fpermissive]
byte* LoraNode::getMessageByte(){return LR.getMessage();}
`

[danieledenaro]

Actually, as far I know, char should be signed or unsigned (for specify type you can use signed or unsigned prefix). But the problem comes out of Arduino pre-compiler that is Processing (in other word Java). This environment accepts byte as data type (not present in C). Other compliling environments, may be, have some problem in casting. So, probably, in next release I will use only char type. I'm sorry, for now if you are forced to don't use Arduino IDE environment.

[khawajamechatronics]

Today I was compiling it for esp8266 using Arduino above error appeared there as well.

[khawajamechatronics]

I shall be thankful if you can help resolve above errors as it wont compile for esp8266 under Arduino IDE.

[danieledenaro]

OK. Tanks for pointing out this compiling problems. First of all I confirm to people reading these messages, that library hasn't problem in standard compiling Arduino IDE. But library can have problems (it doesn't work) in case of Arduino emulation hardware (like ESP8266). This kind of problem comes out of IDE environment that accepts byte as data type although compiler is C (where byte data doesn't exist). Unfortunately IDE pre-compiler masks this circumstance. I commit to make a new release (V3.1) with these changes (byte type substitution and variable time for automatic aknowledge) a.s.a.p.. But byte data type substitution will not consume few time. I'm sorry. Besides consider that I have to verify library in different hardware like ESP8266 and other differences should come out (for example string constant to char*). Any way, emulation is not so simple, and ESP8266 is substantially a complete different CPU compared to ATmega, and I bet there are some problems with other libraries. Tell me if you know any.

[khawajamechatronics]

String constant is warning, Not an error, we can still compile and upload code with warning, The main problem are the errors that needs to be solved asap.

[danieledenaro]

Please, try to add "typedef unsigned char byte ;" at the begining of all *h files (LoraNodes.h, LORA.h etc.).
I need to know if this is enough for compiling with ESP8266, before publishing new release. Tel me also if there are problem with AES cryptography.
Thanks.

[khawajamechatronics]

1- Typedef doesnt solve the issue, still same error, invalid conversion from 'unsigned char*' to 'char*'
2- AES compilation is solved which I explained in #3 , so just add those changes.

[danieledenaro]

So, only conversion to char works, doesn't it? Have you tried to use "typedef char byte ;" ?
Everithing is ok? I suppose compiler uses char as signed char, but I'm not sure that this solution can have no effects. If you confirm everithing works, I will introduce this definition in new release.
Thank for AES correction.

[khawajamechatronics]

/AES.h:39:23: error: 'byte' has a previous declaration as 'typedef uint8_t byte'