endianness

How to check whether a system is big endian or little endian?

由 谁说我不能喝 提交于 2019-11-27 03:00:52
How to check whether a system is big endian or little endian? belwood In C, C++ int n = 1; // little endian if true if(*(char *)&n == 1) {...} See also: Perl version In Python: from sys import byteorder print(byteorder) # will print 'little' if little endian Another C code using union union { int i; char c[sizeof(int)]; } x; x.i = 1; if(x.c[0] == 1) printf("little-endian\n"); else printf("big-endian\n"); It is same logic that belwood used. If you are using .NET: Check the value of BitConverter.IsLittleEndian . A one-liner with Perl (which should be installed by default on almost all systems):

C program to check little vs. big endian [duplicate]

由 折月煮酒 提交于 2019-11-27 02:36:25
Possible Duplicate: C Macro definition to determine big endian or little endian machine? int main() { int x = 1; char *y = (char*)&x; printf("%c\n",*y+48); } If it's little endian it will print 1. If it's big endian it will print 0. Is that correct? Or will setting a char* to int x always point to the least significant bit, regardless of endianness? In short, yes. Suppose we are on a 32-bit machine. If it is little endian, the x in the memory will be something like: higher memory -----> +----+----+----+----+ |0x01|0x00|0x00|0x00| +----+----+----+----+ A | &x so (char*)(&x) == 1 , and *y+48 ==

Reading “integer” size bytes from a char* array.

由 [亡魂溺海] 提交于 2019-11-27 01:59:23
问题 I want to read sizeof(int) bytes from a char* array. a) In what scenario's do we need to worry if endianness needs to be checked? b) How would you read the first 4 bytes either taking endianness into consideration or not. EDIT : The sizeof(int) bytes that I have read needs to be compared with an integer value. What is the best approach to go about this problem 回答1: Do you mean something like that?: char* a; int i; memcpy(&i, a, sizeof(i)); You only have to worry about endianess if the source

Endianness of integers in Python

由 你说的曾经没有我的故事 提交于 2019-11-27 01:51:26
问题 I'm working on a program where I store some data in an integer and process it bitwise. For example, I might receive the number 48, which I will process bit-by-bit. In general the endianness of integers depends on the machine representation of integers, but does Python do anything to guarantee that the ints will always be little-endian? Or do I need to check endianness like I would in C and then write separate code for the two cases? I ask because my code runs on a Sun machine and, although

How to make GCC generate bswap instruction for big endian store without builtins?

由 孤人 提交于 2019-11-27 01:50:25
问题 I'm working on a function that stores a 64-bit value into memory in big endian format. I was hoping that I could write portable C99 code that works on both little and big endian platforms and have modern x86 compilers generate a bswap instruction automatically without any builtins or intrinsics . So I started with the following function: #include <stdint.h> void encode_bigend_u64(uint64_t value, void *vdest) { uint64_t bigend; uint8_t *bytes = (uint8_t*)&bigend; bytes[0] = value >> 56; bytes

Building a 32-bit float out of its 4 composite bytes

由 筅森魡賤 提交于 2019-11-27 01:27:27
I'm trying to build a 32-bit float out of its 4 composite bytes. Is there a better (or more portable) way to do this than with the following method? #include <iostream> typedef unsigned char uchar; float bytesToFloat(uchar b0, uchar b1, uchar b2, uchar b3) { float output; *((uchar*)(&output) + 3) = b0; *((uchar*)(&output) + 2) = b1; *((uchar*)(&output) + 1) = b2; *((uchar*)(&output) + 0) = b3; return output; } int main() { std::cout << bytesToFloat(0x3e, 0xaa, 0xaa, 0xab) << std::endl; // 1.0 / 3.0 std::cout << bytesToFloat(0x7f, 0x7f, 0xff, 0xff) << std::endl; // 3.4028234 × 10^38 (max single

How do I convert a big-endian struct to a little endian-struct?

由 此生再无相见时 提交于 2019-11-27 01:21:36
问题 I have a binary file that was created on a unix machine. It's just a bunch of records written one after another. The record is defined something like this: struct RECORD { UINT32 foo; UINT32 bar; CHAR fooword[11]; CHAR barword[11]; UNIT16 baz; } I am trying to figure out how I would read and interpret this data on a Windows machine. I have something like this: fstream f; f.open("file.bin", ios::in | ios::binary); RECORD r; f.read((char*)&detail, sizeof(RECORD)); cout << "fooword = " << r

Convert big endian to little endian when reading from a binary file [duplicate]

由 China☆狼群 提交于 2019-11-27 00:56:42
问题 This question already has an answer here: How do I convert between big-endian and little-endian values in C++? 30 answers I've been looking around how to convert big-endian to little-endians. But I didn't find any good that could solve my problem. It seem to be there's many way you can do this conversion. Anyway this following code works ok in a big-endian system. But how should I write a conversion function so it will work on little-endian system as well? This is a homework, but it just an

Can I safely assume that Windows installations will always be little-endian?

由 北战南征 提交于 2019-11-26 23:06:17
问题 I'm writing a userspace filesystem driver on Windows and endianness conversions are something I've been dealing with, as this particular filesystem always stores values in little-endian format and the driver is expected to convert them (if necessary) for the CPU it's running on. However, I find myself wondering if I even need to worry about endianness conversions, since as far as I can tell, desktop Windows only supports little-endian architectures (IA32, x86-84, etc.), and therefore, the on

BinaryWriter Endian issue

由 耗尽温柔 提交于 2019-11-26 22:46:39
I am using BinaryWriter class to write a binary file to disk. When I invoke the Write method, passing an unsigned short value, it writes it in little-endian format. For example: bw.Write(0xA000); writes the value in the binary file as 0x00 0xA0. Is there a way to make BInaryWriter use Big Endian? If not, is it possible to create a new class, inheriting BinaryWriter and overload the Write function to make it write big endian? You can use my EndianBinaryWriter in MiscUtil . That lets you specify the endianness you want. There's also EndianBinaryReader and EndianBitConverter . EndianBinaryWriter
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