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# Unit/SInt

## Description

The `UInt`/`SInt` type corresponds to a vector of bits that can be used for signed/unsigned integer arithmetic.

## Declaration

The syntax to declare an integer is as follows: (everything between [] is optional)

Syntax

Description

Return

UInt[()]
SInt[()]

Create an unsigned/signed integer, bits count is inferred

UInt
SInt
UInt(x bits)
SInt(x bits)

Create an unsigned/signed integer with x bits

UInt
SInt
U(value: Int[,x bits])
S(value: Int[,x bits])

Create an unsigned/signed integer assigned with ‘value’

UInt
SInt
U”[[size’]base]value”
S”[[size’]base]value”

Create an unsigned/signed integer assigned with ‘value’ (Base : ‘h’, ‘d’, ‘o’, ‘b’)

UInt
SInt
U([x bits,] element, …)
S([x bits,] element, …)

Create an unsigned integer assigned with the value specified by elements

UInt
SInt
```val myUInt = UInt(8 bits)
myUInt := U(2,8 bits)
myUInt := U(2)
myUInt := U"0000_0101"  // Base per default is binary => 5
myUInt := U"h1A"        // Base could be x (base 16)
//               h (base 16)
//               d (base 10)
//               o (base 8)
//               b (base 2)
myUInt := U"8'h1A"
myUInt := 2             // You can use scala Int as literal value

val myBool := myUInt === U(7 -> true,(6 downto 0) -> false)
val myBool := myUInt === U(myUInt.range -> true)

// For assignement purposes, you can omit the U/S, which also alow the use of the [default -> ???] feature
myUInt := (default -> true)                        //Assign myUInt with "11111111"
myUInt := (myUInt.range -> true)                   //Assign myUInt with "11111111"
myUInt := (7 -> true, default -> false)            //Assign myUInt with "10000000"
myUInt := ((4 downto 1) -> true, default -> false) //Assign myUInt with "00011110"
```

## Operators

The following operators are available for the `UInt` and `SInt` type

### Logic

Operator

Description

Return type

x ^ y

Logical XOR

Bool

~x

Bitwise NOT

T(w(x) bits)

x & y

Bitwise AND

T(max(w(xy) bits)

x | y

Bitwise OR

T(max(w(xy) bits)

x ^ y

Bitwise XOR

T(max(w(xy) bits)

x.xorR

XOR all bits of x

Bool

x.orR

OR all bits of x

Bool

x.andR

AND all bits of x

Bool

x >> y

Arithmetic shift right, y : Int

T(w(x) - y bits)

x >> y

Arithmetic shift right, y : UInt

T(w(x) bits)

x << y

Arithmetic shift left, y : Int

T(w(x) + y bits)

x << y

Arithmetic shift left, y : UInt

T(w(x) + max(y) bits)

x |>> y

Logical shift right, y : Int/UInt

T(w(x) bits)

x |<< y

Logical shift left, y : Int/UInt

T(w(x) bits)

x.rotateLeft(y)

Logical left rotation, y : UInt/Int

T(w(x) bits)

x.rotateRight(y)

Logical right rotation, y : UInt/Int

T(w(x) bits)

x.clearAll[()]

Clear all bits

x.setAll[()]

Set all bits

x.setAllTo(value : Boolean)

Set all bits to the given Boolean value

x.setAllTo(value : Bool)

Set all bits to the given Bool value

```// Bitwise operator
val a, b, c = SInt(32 bits)
c := ~(a & b) //  Inverse(a AND b)

val all_1 = a.andR // Check that all bit are equal to 1

// Logical shift
val uint_10bits = uint_8bits << 2  // shift left (result on 10 bits)
val shift_8bits = uint_8bits |<< 2 // shift left (result on 8 bits)

// Logical rotation
val myBits = uint_8bits.rotateLeft(3) // left bit rotation

// Set/clear
val a = B"8'x42"
when(cond){
a.setAll() // set all bits to True when cond is True
}
```

### Arithmetic

Operator

Description

Return

x + y

T(max(w(x), w(y) bits)

x - y

Subtraction

T(max(w(x), w(y) bits)

x * y

Multiplication

T(w(x) + w(y) bits)

x / y

Division

T(w(x) bits)

x % y

Modulo

T(w(x) bits)

```// Addition
val res = mySInt_1 + mySInt_2
```

### Comparison

Operator

Description

Return type

x === y

Equality

Bool

x =/= y

Inequality

Bool

x > y

Greater than

Bool

x >= y

Greater than or equal

Bool

x < y

Less than

Bool

x <= y

Less than or equal

Bool

```// Comparaison between two SInt
myBool := mySInt_1 > mySInt_2

// Comparaison between UInt and a literal
myBool := myUInt_8bits >= U(3, 8 bits)

when(myUInt_8bits === 3){

}
```

### Type cast

Operator

Description

Return

x.asBits

Binary cast in Bits

Bits(w(x) bits)

x.asUInt

Binary cast in UInt

UInt(w(x) bits)

x.asSInt

Binary cast in SInt

SInt(w(x) bits)

x.asBools

Cast into a array of Bool

Vec(Bool, w(x))

S(x: T)

Cast a Data into a SInt

SInt(w(x) bits)

U(x: T)

Cast a Data into an UInt

UInt(w(x) bits)

To cast a Bool, a Bits or a SInt into a UInt, you can use `U(something)`. To cast things into a SInt, you can use `S(something)`

```// cast a SInt to Bits
val myBits = mySInt.asBits

// create a Vector of bool
val myVec = myUInt.asBools

// Cast a Bits to SInt
val mySInt = S(myBits)
```

### Bit extraction

Operator

Description

Return

x(y)

Bool

x(offset, width)

Read bitfield, offset: UInt, width: Int

T(width bits)

x(range)

Read a range of bit. Ex : myBits(4 downto 2)

T(range bits)

x(y) := z

Assign bits, y : Int/UInt

Bool

x(offset, width) := z

Assign bitfield, offset: UInt, width: Int

T(width bits)

x(range) := z

Assign a range of bit. Ex : myBits(4 downto 2) := U”010”

T(range bits)

```// get the element at the index 4
val myBool = myUInt(4)

// assign
mySInt(1) := True

// Range
val myUInt_8bits = myUInt_16bits(7 downto 0)
val myUInt_7bits = myUInt_16bits(0 to 6)
val myUInt_6bits = myUInt_16Bits(0 until 6)

mySInt_8bits(3 downto 0) := mySInt_4bits
```

### Misc

Operator

Description

Return

x.getWidth

Return bitcount

Int

x.msb

Return the most significant bit

Bool

x.lsb

Return the least significant bit

Bool

x.range

Return the range (x.high downto 0)

Range

x.high

Return the upper bound of the type x

Int

x ## y

Concatenate, x->high, y->low

Bits(w(x) + w(y) bits)

x @@ y

Concatenate x:T with y:Bool/SInt/UInt

T(w(x) + w(y) bits)

x.subdivideIn(y slices)

Subdivide x in y slices, y: Int

Vec(T, y)

x.subdivideIn(y bits)

Subdivide x in multiple slices of y bits, y: Int

Vec(T, w(x)/y)

x.resize(y)

Return a resized copy of x, if enlarged, it is filled with zero
for UInt or filled with the sign for SInt, y: Int

T(y bits)

x.resized

Return a version of x which is allowed to be automatically
resized were needed

T(w(x) bits)

myUInt.twoComplement(en: Bool)

Use the two’s complement to transform an UInt into an SInt

SInt(w(myUInt) + 1)

mySInt.abs

Return the absolute value of the SInt value

SInt(w(mySInt))

mySInt.abs(en: Bool)

Return the absolute value of the SInt value when en is True

SInt(w(mySInt))

```myBool := mySInt.lsb  // equivalent to mySInt(0)

// Concatenation
val mySInt = mySInt_1 @@ mySInt_1 @@ myBool
val myBits = mySInt_1 ## mySInt_1 ## myBool

// Subdivide
val sel = UInt(2 bits)
val mySIntWord = mySInt_128bits.subdivideIn(32 bits)(sel)
// sel = 0 => mySIntWord = mySInt_128bits(127 downto 96)
// sel = 1 => mySIntWord = mySInt_128bits( 95 downto 64)
// sel = 2 => mySIntWord = mySInt_128bits( 63 downto 32)
// sel = 3 => mySIntWord = mySInt_128bits( 31 downto  0)

// if you want to access in a reverse order you can do
val myVector   = mySInt_128bits.subdivideIn(32 bits).reverse
val mySIntWord = myVector(sel)

// Resize
myUInt_32bits := U"32'x112233344"
myUInt_8bits  := myUInt_32bits.resized       // automatic resize (myUInt_8bits = 0x44)
myUInt_8bits  := myUInt_32bits.resize(8)     // resize to 8 bits (myUInt_8bits = 0x44)

// Two's complement
mySInt := myUInt.twoComplement(myBool)

// Absolute value
mySInt_abs := mySInt.abs
```