Well, the "Endianness" theme was always a little bit confusing to me, but i have never faced any problems which required me to even think about the default behaviour of binary writers/readers that i used. I am writing a PNG decoder in c# right now. PNG file format specification states that all numbers are stored in a big endian notation ...
Im not sure if endian is the right word but.. I have been parsing through a PNG file and I have noticed that all of the integer values are in big endian. Is this true? For example, the width and height are stored in the PNG file as 32bit unsigned integers. My image is 16x16 and in the file its stored as: 00 00 00 10 when it should b...
I've got raw data streams from image files, like: vector<char> rawData(fileSize); ifstream inFile("image.jpg"); inFile.read(&rawData[0]); I want to parse the headers of different image formats for height and width. Is there a portable library that can can read ints, longs, shorts, etc. from the buffer/stream, converting for endianess ...
Searching online, I have found the following routine for calculating the sign of a float in IEEE format. This could easily be extended to a double, too. // returns 1.0f for positive floats, -1.0f for negative floats, 0.0f for zero inline float fast_sign(float f) { if (((int&)f & 0x7FFFFFFF)==0) return 0.f; // test exponent & mantis...
Hi everyone, I'm fighting with socket programming now and I've encountered a problem, which I don't know how to solve in a portable way. The task is simple : I need to send the array of 16 bytes over the network, receive it in a client application and parse it. I know, there are functions like htonl, htons and so one to use with uint16 ...
so the following converts big endians to little ones uint32_t ntoh32(uint32_t v) { return (v << 24) | ((v & 0x0000ff00) << 8) | ((v & 0x00ff0000) >> 8) | (v >> 24); } works. like a charm. I read 4 bytes from a big endian file into char v[4] and pass it into the above function as ntoh32 (* reinterpret_cas...
Write a program to determine whether a computer is big-endian or little-endian. bool endianness() { int i = 1; char *ptr; ptr = (char*) &i; return (*ptr); } So I have the above function. I don't really get it. ptr = (char*) &i, which I think means a pointer to a character at address of where i is sitting, so if an...
I have a stream of bytes which contains a flag which identifies the endianness of the data in the header. I want to read the doubles from the stream, which will presumably need to be different if the endianness of the data in the header is different? I am currently using a BinaryReader and calling ReadDouble to read the data from the s...
Hi all, With the sort of programs I write (working with raw file data) I often need functions to convert between big and little endian. Usually I write these myself (which is covered by many other posts here) but I'm not that keen on doing this for a number of reasons - the main one being lack of testing. I don't really want to spend ...
I have the following code: // Incrementer datastores.cmtDatastores.u32Region[0] += 1; // Decrementer datastores.cmtDatastores.u32Region[1] = (datastores.cmtDatastores.u32Region[1] == 0) ? 10 : datastores.cmtDatastores.u32Region[1] - 1; // Toggler datastores.cmtDatastores.u32Region[2] = (datast...
I'm using the miscutil library to communicate between and Java and C# application using a socket. I am trying to figure out the difference between the following code (this is Groovy, but the Java result is the same): import java.io.* def baos = new ByteArrayOutputStream(); def stream = new DataOutputStream(baos); stream.writeInt(5000)...
I have a system where a remote agent sends serialized structures (from an embedded C system) for me to read and store via IP/UDP. In some cases I need to send back the same structure types. I thought I had a nice setup using Marshal.PtrToStructure (receive) and Marshal.StructureToPtr (send). However, a small gotcha is that the network bi...
I am reading a file byte-by-byte. Say for example i have this byte: 0x41 (0100 0001) represented in hex. Now, I want the first three bits of this byte, i.e (010). I can use bitwise logic to extract the first three bits, but my question is will the first three bits be independent of endianess of the machine.(i.e they can't be 001)? Th...
I've got the following C++ code : template <int isBigEndian, typename val> struct EndiannessConv { inline static val fromLittleEndianToHost( val v ) { union { val outVal __attribute__ ((used)); uint8_t bytes[ sizeof( val ) ] __attribute__ ((used)); } ; outVal = v; ...
Hello I'm writing a program that uses QUdpSocket for transmiting data over the network. This is my first socket program, and I've come across an interesting problem called Endianness. My actual question in, do I have to worry about Endianness when I'm using QNetwork as my sockets library? If I do have to worry, what do I have to do to ...
Hi all, I'm doing some endian-sensitive file manipulation on iPhone. Are there standard macros or #defines in that environment that indicate native endianness and offer swapping if necessary? I know I can check in advance and just do the right thing for this particular architecture, but wondering if there are cleaner ways of doing the ri...
Hello, I am using on the client C# where I am converting double values to byte array. I am using java on the server and I am using writeDouble and readDouble to convert double values to byte arrays. The problem is the double values from java at the end are not the double values at the begin giving to c# writeDouble in Java Converts...
I have a binary file of doubles that I need to load using C++. However, my problem is that it was written in big-endian format but the fstream >> operator will then read the number wrong because my machine is little-endian. It seems like a simple problem to resolve for integers, but for doubles and floats the solutions I have found won't...
Hey, I've written a function to copy any variable type into a byte vector, however whenever I insert something it gets inserted in reverse. Here's the code. template <class Type> void Packet::copyToByte(Type input, vector<uint8_t>&output) { copy((uint8_t*) &input, ((uint8_t*) &input) + sizeof(Type), back_inserter(output)); } Now ...
Hello people! This is currently a homework project that me and my teammate are stuck on. We haven't been given much of an introduction into Assembly, and this is supposed to be our first homework exercise. The task is to create a program that converts 0xAABBCCDD into 0xDDCCBBAA. I'm not looking for an answer, as that would defeat the ...