swapbytes - Swap byte ordering - MATLAB (original) (raw)
Syntax
Description
`Y` = swapbytes([X](#mw%5Fc7fb64d2-22a1-48b0-9dd3-9d8212c91697)) swaps the byte ordering of each element in array X from little endian to big endian (or vice versa). All elements of the input array must be full, noncomplex, and numeric.
Examples
Swap the byte ordering for a scalar 32-bit value. Use hexadecimal representation to show the conversion from little endian to big endian.
X = uint32(hex2dec('4D3C2B1A')); Y = dec2hex(swapbytes(X))
Starting in R2019b, you can also write a hexadecimal value as a literal using the 0x or 0X prefix (for more information, see Hexadecimal and Binary Values). Specify the number X as a hexadecimal literal. Swap the byte ordering.
X = 0x4D3C2B1A; Y = dec2hex(swapbytes(X))
Swap the byte ordering for each element of a 1-by-4 vector.
format short X = uint16([0 1 128 65535])
X = 1×4 uint16 row vector
0 1 128 65535Y = 1×4 uint16 row vector
0 256 32768 65535Examine the output in hexadecimal notation to show the endian conversion.
X = 1×4 uint16 row vector
0000 0001 0080 ffff
Y = 1×4 uint16 row vector
0000 0100 8000 ffff
Create a three-dimensional array A of 16-bit integers. Swap the byte ordering of each element. Use hexadecimal representation to show the endian conversion.
format hex X = uint16(magic(3)150); X(:,:,2) = X40; X
X = 3×3×2 uint16 array X(:,:,1) =
04b0 0096 0384 01c2 02ee 041a 0258 0546 012c
X(:,:,2) =
bb80 1770 8ca0 4650 7530 a410 5dc0 d2f0 2ee0
Y = 3×3×2 uint16 array Y(:,:,1) =
b004 9600 8403 c201 ee02 1a04 5802 4605 2c01
Y(:,:,2) =
80bb 7017 a08c 5046 3075 10a4 c05d f0d2 e02e
Input Arguments
Numeric value, specified as a scalar, vector, matrix, or multidimensional array. Theswapbytes operation is elementwise when X is nonscalar.
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64
More About
Computer systems store data in pieces of bytes. There are two ways to store a numeric value in computer memory: little endian and big endian. In little-endian style, the bytes are written from left to right in increasing significance. In big-endian style, the bytes are written from left to right in decreasing significance. Theswapbytes function swaps the byte ordering in memory, converting little endian to big endian (and vice versa).
The following figure illustrates the conversion for a 32-bit (4-byte) hexadecimal number, 4D3C2B1A. In hexadecimal notation, one byte is represented by two digits. Each box in the little-endian picture shows one byte of data (4D, 3C, 2B, and 1A). The swapbytes function swaps the order of these boxes or bytes.
Extended Capabilities
Theswapbytes function fully supports tall arrays. For more information, see Tall Arrays.
Usage notes and limitations:
Inheritance of the class of the input to swapbytes in aMATLAB Function block is supported only when the class of the input isdouble. For non-double inputs, the input port data types must be specified, not inherited.
Usage notes and limitations:
Inheritance of the class of the input to swapbytes in aMATLAB Function block is supported only when the class of the input isdouble. For non-double inputs, the input port data types must be specified, not inherited.
The swapbytes function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).
Version History
Introduced before R2006a