i am doing corebluetooth application and able to receive the data from the peripheral in the hex format i need to parse the data to integer format and is there any method to convert the data to integer format from hex format please help Below values iam getting
NSstring *data is
011f6d000000160000000000040507010500054607db051705173a0600053d
Nslog(#"data is Ð`#PpPT`}°QpQs")
And also please help if there is any method for converting the data to the string also.
Define a struct with all the correct types and order. Point the struct to the data. Then just access the items via the struct elements. Be careful with the types, it is probably best to use well defined types such as int8_t, uint8_t, uint16_t, int16_t, etc to insure the correct element size. You will want a "packed" struct, not alligned to the CPU alignment size.
Related
In Swift, We can convert String to Data, and convert from UIImage to Data also. So, what is different between two Data? Can Anyone help. Thanks.
To quote Apple's documentation:
The Data value type allows simple byte buffers to take on the behavior of Foundation objects.
Essentially it provides a byte buffer representation of Foundation objects, which allows you to access/manipulate the object's bytes in memory.
You can read more about the Data structure on Apple's documentation: https://developer.apple.com/documentation/foundation/data
I'm trying to extract binary data from QR-code with zbar (the QR-code was originally encoded using the iOS SDK passing a NSData object). Unfortunately the ZBarSymbol class only provides the content in a NSString member. Trying to extract a NSData from it using NSISOLatin1StringEncoding seems to work but still fails in some occasions.
I see in the zbar implementation that it is possible to access an object of type zbar_symbol_t that contains a pointer to char. By looking into it, it seems to contain the original content but with additional data of some kind, this is an example:
Original data: 9e7328c16bca3aaff532440917e4df6e155b96bd
Data in zbar_symbol_t: c29e7328c3816bc38a3ac2afc3b532440917c3a4c39f6e155bc296c2bd
Anyone who knows what is exactly that data in zbar_symbol_t, why it is different from data I originally placed in the QR-code and how it is possible, if possible at all, to extract my original data from that?
I am not sure what those bytes represent, probably zbar is trying to interprete the bytes as a UTF-8 string even though the QR is in byte mode.
Switching to zxing fixed everything, there is no interleaved unexpected byte and the raw data contains the entire QR code including the mode, terminator, padding etc... Also it seems to never fails, while zbar seemed to fail sometime.
is it possible to parse an incoming google protocol buffers datagram without any .proto file? I merely now its been serialized using protocol buffers but have no idea about the IDL file.
I'm looking for a way to just iterate through any value by some sort of reflection? Is this possible?
Thank you!
protoc --decode_raw < my_file
You need to take the following things into account when inspecting the output:
None of the field names are visible, just the tag numbers.
All varint-fields are shown as integers. This is ok for most types, but sint* will appear in the "zigzagged" format.
Doubles and floats will be shown as hex.
Bytes, string fields and submessages all appear the same, i.e. just a bunch of bytes.
If you want to decode the messages programmatically, you can write your own .proto file after you have figured out what the fields mean using the above method.
I am trying to learn iOs programming. and I suppose this is a bit of a reverse question.
I have just completed a tutorial on youtube using Xcode to create a simple iPhone app that will allow you to store, list and delete data from an SQLite3 database (as the app i want to produce will need a database).
However the bloke who put the video up didn't seem to explain 'why' he did what he did, so I am now trying to understand what each bit of code does
(I come from a PHP and SQL web programming background, so I understand accessing databases, calling data rows etc to show the content on a website.)
The one part of this iOs bit I don't quite understand is the %s and %d values used as they didn't seem to be declared anywhere.
The code is;
if(sqlite3_open([dbPathString UTF8String], &personDB)==SQLITE_OK) {
NSString *inserStmt = [NSString stringWithFormat:#"INSERT INTO PERSONS(NAME,AGE) values ('%s', '%d')",[self.nameField.text UTF8String],[self.ageField.text intValue]];
now %s and %d clearly get their values from the self.nameField and self.ageField. However that implies that I could only ever submit two values into a table? or are there other % for other values, but surely then there is a max of 26.
I would be grateful for any explanation you could give.
Also in addition, does anyone have any suggestions about other fully explained ways to learn to code for iOS? especially if you were a starter just learning iOS programming for a first time with limited C programming skills before hand.
The area i am looking for is to create an app that will store some text fields and an image, which either will be stored in a database and the image either in the database or as a link and appropriately named.
I'd like to be able to manipulate the image to resize it so it is optimised for the iPhone display (don't need a HD image in the APP)
Later I'd like to be able to work out how either upload the local database (sqlite3) file to a an online storage (either my own server or dropbox), or synchronise it to an SQL database (from initial looks just exporting the file would be better and embedding the images into a field would be better for this project, even though i know it is not the normal way of doing things)
%s and %d are format specifiers for a null-terminated array of characters and a signed 32-bit integer respectively. You can find the details about specifiers in the String Programming Guide. However, you should not format the string this way for a SQLite statement as it puts you at risk of SQL injection. Instead you should bind the values using ? and the appropriate sqlite3_bind* function. For your situation you would use sqlite3_bind_text for NAME and sqlite3_bind_int for AGE.
Have a look at the class reference:
https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html
Here are the string format specifiers:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265
As you can see, %d is outputting an integer while %s is outputting a string.
Part 1:
The % convention "string format specifiers" is a common standard for string substitution.
They are not variables, but typed substitution placeholders.
%s --> string
%d --> number
Part 2:
You might check out the iTunes U course:
iPhone Application Programming '11
by Prof. Jan Borchers
https://itunes.apple.com/us/itunes-u/iphone-application-programming/id474416629
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html
%s
Null-terminated array of 8-bit unsigned characters. Because the %s specifier causes the characters to be interpreted in the system default encoding, the results can be variable, especially with right-to-left languages. For example, with RTL, %s inserts direction markers when the characters are not strongly directional. For this reason, it’s best to avoid %s and specify encodings explicitly.
%d, %D
Signed 32-bit integer (int).
That is what is called a formatted string, basically, it is a way to inject values into a string. The character after the % sign is used to indicate the datatype that the value should be formatted as. In your case, %s is used to indicate a string value and %d is used to indicate a decimal integral value.
This type of string formatting is extremely common; many programming languages provide some mechanism for performing this type of string formatting and the formatting symbols are largely standardized. You can find a more information on the C++ website.
I have a series of messages that are defined by independent structs. These structs share a common header are sent between applications. I am creating a decoder that will take the raw data captures in the messages that were built using these structs and decode/parse them to some plain text.
I have over 1000 different messages that need to be decoded so I am not sure if defining all the struct formats in XML and then using XSL or some translation is the way to go or if there is a better way to do this.
There are times when I will need to decode logs containing over a million messages so performance is a concern.
Any recommendations for techniques/tools/algorithms to go about creating the decoder/parser?
struct:
struct {
dword messageid;
dword datavalue1;
dword datavalue2;
} struct1;
Example raw data:
0101010A0A0A0A0F0F0F0F
Decoded message (desired output):
message id: 0x01010101, datavalue1: 0x0A0A0A0A, datavalue2: 0x0F0F0F0F
I am using C++ to do this development.
Regarding "performance" - if you are using disk IO and possible display IO I doubt your parser/decoder will have much effect unless you use a truly horrible algorithm.
I am also unsure about what the problem is - Given the question right now - you have 3 DWORDs in a struct and you claim that there are over 1000 unique messages based on these values.
Your decoded message does not imply to me that you need any kind of parsing - just straight output seems to work (convert from bytes to ascii representation of a hex value)
If you do have a mapping from a value to a string, then a big switch statement is simple - or alternatively if you want to be able to have these added dynamically or change the display, then I would provide the key/value pairs (mapping) in a config file (text, xml, etc) and then do a lookup as the log file/raw data is read.
map is what I would use in that case.
Perhaps if you provide another specific example of the values and decoded output I can come up with a more appropriate suggestion.
If you have the message definitions already given in the syntax that you've used in your example, you should definitely not try to convert it manually into some other syntax (XML or otherwise).
Instead, you should try to write a compiler that takes these method definitions, and compiles them into a decoder function.
These days, the recommendation is to use ANTLR as the parser generator, using any of the ANTLR languages for the actual compiler (Java, Python, Ruby, C#, C++). That compiler then should output C code, which does the entire decoding and pretty-printing.
You can use yacc or antlr, add appropriate parsing rules, populate some data structure out of it(a tree may be) while parsing, then traverse the data structure and do whatever you like.
I'm going to assume that all you need to do is format the records and output them.
Use a custom code generator. The generated code will look something like this:
typedef struct { word messageid; } Header;
//repeated for each record type
typedef struct {
word messageid;
// <members here>
} Record_##;
//END
void Process(Input inp, Output out) {
char buffer[BIG_ENOUGH];
char *offset;
offset = &buffer[BIG_ENOUGH];
while(notEnd) {
if(&offset[sizeof(LargestStruct)] >= &buffer[BIG_ENOUGH])
// move remaining buffer to start and fill tail from inp
Header *hpt = (Header*)offset;
switch(hpt->messageid)
{
//repeated for each record type
case <recond ID for given type>:
{
Record_##* rpt = (Record_##*)offset;
outp.format("name1: %t, ...\n", rpt->name1, ...);
offset += sizeof(Record_##);
break;
}
//END
}
}
}
Most of that's boiler plate so writing a program to generate it shouldn't be to hard.
If you need more processing, I think this idea could be tweaked some to make that work as well.
Edit: after re-reading the question, it looks like you might have the structs defined already. In that cases you can just #include them and use them directly. However then you end up with the issue of how to parse the structs to generate the input to the formating function. Awk or sed might be handy there.