bit2int

Convert bits to integers

Since R2021b

Syntax

Y = bit2int(X,n)

Y = bit2int(X,n,msbfirst)

Y = bit2int(___,IsSigned=tf)

Description

Y = bit2int(X,n) converts n column-wise bit elements in X to integer values, with the first bit as the most significant bit (MSB).

Y = bit2int(X,n,msbfirst) indicates whether the first bit in each set of n column-wise bits from X is the MSB or the least significant bit (LSB).

Y = bit2int(___,IsSigned=tf) specifies optional Name-Value pair IsSigned=tf. The value for tf is a logical, either true or false to indicate the signedness of the integer. The default is false. When you set tf to true, the first bit in each block of n bits is considered to be a signed bit and the output may contain negative values. If the datatype of X is any of the unsigned integer types and you set tf to true, then the datatype of Y is the smallest signed integer type that can support the number of input bits.

Examples

Convert Vector of Bits to Integers

Specify a column vector of bits.

X = [1 0 1 0 1 0 1 0]';

Specify for four column-wise bit elements of the input vector to be converted to integer values. Then, convert the bits to integers.

n = 4;
Y = bit2int(X,n)

Y = 2×1

    10
    10

Convert Matrix of Bits to Integers

Specify a matrix of bits.

X = int8([1 1 0; 0 1 1]')

X = 3x2 int8 matrix

   1   0
   1   1
   0   1

Specify that the first bit in each set of three column-wise bit elements is the LSB. Then, convert the bits to integers.

n = 3;
msbfirst = false;
Y = bit2int(X,n,msbfirst)

Y = 1x2 int8 row vector

   3   6

Convert Array of Bits to Integers

Specify an array of bits.

X = randi([0,1],8,2,2,'uint8') 

X = 8x2x2 uint8 array
X(:,:,1) =

   1   1
   1   1
   0   0
   1   1
   1   1
   0   0
   0   1
   1   0


X(:,:,2) =

   0   1
   1   1
   1   1
   1   0
   1   1
   0   0
   1   1
   1   0

Specify that the first bit in each set of four column-wise bit elements is the MSB. Then, convert the bits to integers.

n = 4;
msbfirst = true;
Y = bit2int(X,n,msbfirst)

Y = 2x2x2 uint8 array
Y(:,:,1) =

   13   13
    9   10


Y(:,:,2) =

    7   14
   11   10

Convert Array of Signed Bits to Integers

Specify an array of bits.

X = [1 1 0 1 1 0 0 1; 1 0 1 1 0 0 1 0]'

X = 8×2

     1     1
     1     0
     0     1
     1     1
     1     0
     0     0
     0     1
     1     0

Specify that the first bit in each set of four column-wise bit elements is the sign bit. Then, convert the bits to integers.

n = 4;
tf = true;
Y = bit2int(X,n,IsSigned=tf)

Y = 2×2

    -3    -5
    -7     2

Convert the same bit array specifying that the first bit in each set of four column-wise bit elements is not the sign bit.

tf = false;
Y = bit2int(X,n,IsSigned=tf)

Y = 2×2

    13    11
     9     2

Input Arguments

X — Bits

column vector | matrix | 3-D array

Bits, specified as a column vector, matrix, or 3-D array of numeric or logical 0s and 1s.

Example: [1 0 1 0 1 0 1 0]' specifies an input column vector of size 8-by-1.

Note

The number of rows in X must be a multiple of input n.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical

n — Number of bits to be converted

positive integer

Number of bits to be converted to integers, specified as a positive integer. The number of bits, n, includes the signed bit.

Data Types: double

msbfirst — Specification of MSB first

true or 1 (default) | false or 0

Specification of MSB first, specified as a numeric or logical 1 (true) or 0 (false).

• true –– For each set of n column-wise bits in X, the first bit is the MSB.

• false –– For each set of n column-wise bits in X, the first bit is the LSB.

Data Types: logical

Output Arguments

Y — Integer representation of input bits

scalar | column vector | matrix | 3-D array

Integer representation of input bits, returned as a scalar, column vector, matrix, or 3-D array. The function returns the integer-equivalent value for each set of n column-wise bits in X. Output Y has same dimensions as input X except that the number of rows in Y is n times less than the number of rows in X.

The data type of Y depends on the data type of X.

• If X is of data type double or logical, then Y is of data type double.

• If X is of data type single, then Y is of data type single.

• If X is an integer data type, then the signedness of Y depends on the IsSigned input.

  • If the value of Y can be contained in the same integer data type, then Y is of the same data type as X.

  • If the value of Y cannot be contained in the same integer data type as X, then the function sets the data type of Y to an integer data type that is big enough to contain its value.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• For code generation,

  • When input X is an integer data type, the input n must be compile-time constant. For example, use coder.Constant(n).

  • The name-value pair input IsSigned=tf must be compile-time constant.

Version History

Introduced in R2021b

R2023a: Add support for signed output

bit2int now supports conversion of signed binary values (2s-complement values) to signed integer output.

The function added the IsSigned=tf name-value. The value for tf is a logical, either true or false to indicate the signedness of the integer. The default is false. When you set tf to true, the first bit in each block of n bits is considered to be a signed bit and the output may contain negative values.