bitget

Get bits at certain positions

Syntax

c = bitget(a, bit)

Description

c = bitget(a, bit) returns the values of the bits at the positions specified by bit in a as unsigned integers of word length 1.

Examples

Get Bit When Input and Index Are Both Scalar

Consider the following unsigned fixed-point fi number with a value of 85, word length 8, and fraction length 0:

a = fi(85,0,8,0);
disp(bin(a))

01010101

Get the binary representation of the bit at position 4:

c = bitget(a,4);

bitget returns the bit at position 4 in the binary representation of a.

Get Bit When Input Is a Matrix and the Index Is a fi

Begin with a signed fixed-point 3-by-3 matrix with word length 4 and fraction length 0.

a = fi([2 3 4;6 8 2;3 5 1],0,4,0);
disp(bin(a))

0010   0011   0100
0110   1000   0010
0011   0101   0001

Get the binary representation of the bits at a specified position.

c = bitget(a,fi(2))

c = 
     1     1     0
     1     0     1
     1     0     0

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Unsigned
            WordLength: 1
        FractionLength: 0

MATLAB® returns a matrix of the bits in position fi(2) of a. The output matrix has the same dimensions as a, and a word length of 1.

Get Bit When Both Input and Index Are Vectors

Begin with a signed fixed-point vector with word length 16, fraction length 4.

a = fi([86 6 53 8 1],0,16,4);
disp(bin(a))

0000010101100000   0000000001100000   0000001101010000   0000000010000000   0000000000010000

Create a vector that specifies the positions of the bits to get.

bit = [1,2,5,7,4]

bit = 1×5

     1     2     5     7     4

Get the binary representation of the bits of a at the positions specified in bit.

c = bitget(a,bit)

c = 
     0     0     1     0     0

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Unsigned
            WordLength: 1
        FractionLength: 0

bitget returns a vector of the bits of a at the positions specified in bit. The output vector has the same length as inputs, a and bit, and a word length of 1.

Get Bit When Input Is Scalar and Index Is a Vector

Create a default fi object with a value of pi.

a = fi(pi);
disp(bin(a))

0110010010001000

The default object is signed with a word length of 16.

Create a vector of the positions of the bits you want to get in a, and get the binary representation of those bits.

bit = fi([15,3,8,2]);
c = bitget(a,bit)

c = 
     1     0     1     0

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Unsigned
            WordLength: 1
        FractionLength: 0

MATLAB® returns a vector of the bits in a at the positions specified by the index vector, bit.

Input Arguments

a — Input array

scalar | vector | matrix | multidimensional array

Input array, specified as a scalar, vector, matrix, or multidimensional array of fixed-point fi objects. If a and bit are both nonscalar, they must have the same dimension. If a has a signed numerictype, the bit representation of the stored integer is in two's complement representation.

Data Types: fixed-point fi

bit — Bit index

scalar | vector | matrix | multidimensional array

Bit index, specified as a scalar, vector, matrix or multidimensional array of fi objects or built-in data types. If a and bit are both nonscalar, they must have the same dimension. bit must contain integer values between 1 and the word length of a, inclusive. The LSB (right-most bit) is specified by bit index 1 and the MSB (left-most bit) is specified by the word length of a. bit does not need to be a vector of sequential bit positions; it can also be a variable index value.

a = fi(pi,0,8);
a.bin

11001001

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

Output Arguments

c — Output array

scalar | vector | matrix | multidimensional array

Output array, specified as an unsigned scalar, vector, matrix, or multidimensional array with WordLength 1.

If a is an array and bit is a scalar, c is an unsigned array with word length 1. This unsigned array comprises the values of the bits at position bit in each fixed-point element in a.

If a is a scalar and bit is an array, c is an unsigned array with word length 1. This unsigned array comprises the values of the bits in a at the positions specified in bit.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

For VHDL^®, generates the slice operator: a(idx).

For Verilog^®, generates the slice operator: a[idx].

Version History

Introduced before R2006a