Sysquake Pro – Table of Contents
Sysquake for LaTeX – Table of Contents
Library - bitfield
Library bitfield implements the constructor and methods of class bitfield for bit fields (binary numbers). Basic arithmetic operators and functions are overloaded to support expressions with the same syntax as for numbers and matrices. Contrary to integer numbers, bitfield objects have a length (between 1 and 32) and are displayed in binary.
The following statement makes available functions defined in bitfield:
use bitfield
Functions
bitfield::beginning
First bit position in a bitfield.
Syntax
use bitfield a(...beginning...)
Description
In the index expression of a bitfield, beginning is the position of the least-significant bit, i.e. 0.
See also
bitfield::bitfield, bitfield::end
bitfield::bitfield
Bitfield object constructor.
Syntax
use bitfield a = bitfield a = bitfield(n) a = bitfield(n, wordlength)
Description
bitfield(n,wordlength) creates a bitfield object initialized with the wordlength least significant bits of the nonnegative integer number n. The default value of wordlength is 32 if n is a double, an int32 or a uint32 number; 16 is n is an int16 or uint16 number; or 8 if n is an int8 or uint8 number. Without argument, bitfield gives a bit field of 32 bits 0. Like any integer number in LME, n may be written in base 2, 8, 10, or 16: 0b1100, 014, 12, and 0xc all represent the same number.
The following operators and functions may be used with bitfield arguments, with results analog to the corresponding functions of LME. Logical functions operate bitwise.
| Op. | Function | Op. | Function |
|---|---|---|---|
| & | and | ~ | not |
| == | eq | | | or |
| - | minus | + | plus |
| \ | mldivide | - | uminus |
| / | mrdivide | + | uplus |
| * | mtimes | xor | |
| ~= | ne |
Indexes into bit fields are non-negative integers: 0 represents the least-significant bit, and wordlength-1 the most-significant bit. Unlike arrays, bits are not selected with logical arrays, but with other bit fields where ones represent the bits to be selected; for example a(0b1011) selects bits 0, 1 and 3. This is consistent with the way bitfield::find is defined.
Examples
use bitfield
a = bitfield(123, 16)
a =
0b0000000001111011
b = ~a
b =
0b1111111110000100
b = a * 5
b =
0b0000001001100111
See also
bitfield::disp, bitfield::double
bitfield::disp
Display a bitfield object.
Syntax
use bitfield disp(a)
Description
disp(a) displays bitfield a. It is also executed implicitly when LME displays the bitfield result of an expression which does not end with a semicolon.
See also
bitfield::double
Convert a bitfield object to a double number.
Syntax
use bitfield n = double(a)
Description
double(a) converts bitfield a to double number.
Example
use bitfield a = bitfield(123, 16); double(a) 123
See also
bitfield::end
Last bit position in a bitfield.
Syntax
use bitfield a(...end...)
Description
In the index expression of a bitfield, end is the position of the most-significant bit, i.e. 1 less than the word length.
See also
bitfield::bitfield, bitfield::beginning
bitfield::find
Find the ones in a bitfield.
Syntax
use bitfield ix = find(a)
Description
find(a) finds the bits equal to 1 in bitfield a. The result is a vector of bit positions in ascending order; the least-significant bit is number 0.
Example
use bitfield
a = bitfield(123, 16)
a =
0b0000000001111011
ix = find(a)
ix =
0 1 3 4 5 6
See also
bitfield::int8 bitfield::int16 bitfield::int32
Convert a bitfield object to a signed integer number, with sign extension.
Syntax
use bitfield n = int8(a) n = int16(a) n = int32(a)
Description
int8(a), int16(a), and int32(a) convert bitfield a to an int8, int16, or int32 number respectively. If a has less bits than the target integer and the most significant bit of a is 1, sign extension is performed; i.e. the most significant bits of the result are set to 1, so that it is negative. If a has more bits than the target integer, most significant bits are ignored.
Example
use bitfield
a = bitfield(9, 4);
a =
0x1001
i = int8(a)
i =
210
b = bitfield(i)
b =
0b11111001
See also
uint8, uint16, uint32, bitfield::int8, bitfield::int16, bitfield::int32, bitfield::double, bitfield::bitfield
bitfield::length
Word length of a bitfield.
Syntax
use bitfield wordlength = length(a)
Description
length(a) gives the number of bits of bitfield a.
Example
use bitfield a = bitfield(123, 16); length(a) 16
See also
bitfield::sign
Get the sign of a bitfield.
Syntax
use bitfield s = sign(a)
Description
sign(a) gets the sign of bitfield a. The result is -1 if the most-significant bit of a is 1, 0 if all bits of a are 0, or 1 otherwise.
Example
use bitfield
a = bitfield(5, 3)
a =
0b101
sign(a)
-1
See also
bitfield::uint8 bitfield::uint16 bitfield::uint32
Convert a bitfield object to an unsigned integer number.
Syntax
use bitfield n = uint8(a) n = uint16(a) n = uint32(a)
Description
uint8(a), uint16(a), and uint32(a) convert bitfield a to a uint8, uint16, or uint32 number respectively. If a has more bits than the target integer, most significant bits are ignored.
Example
use bitfield a = bitfield(1234, 16); uint8(a) 210
See also
uint8, uint16, uint32, bitfield::int8, bitfield::int16, bitfield::int32, bitfield::double, bitfield::bitfield