Type Representation

Description of the Verilog representation of Spade types

Types with mixed direction wires are split in two separate variables, typically <name> and <name>_mut. The structure of the forward part is the same as if the backward part didn’t exist, and the backward part is structured as if it were the forward part.

For example, (int<8>, inv &int<9>, int<2>, &mut int<3>) is stored as (int<8>, int<2>) and (int<9>, int<3>).

Tuples

Tuples are stored with their members packed side to side, with the 0th member on the left.

letlet is used to define a variable. Spade infers the type of most variables from context, but you can also specifReturns the value of the first branch if the condition is true, otherwise the second branch.
Note that unlike software languages, Spade does not have conditional execution. You do not conditionally assign values inside if expressiosn, you compute a value and return it.y the type with : <type> before the =. x: (int<8>Type used to represent signed integers. The generic parameter (<N>) specifReturns the value of the first branch if the condition is true, otherwise the second branch.
Note that unlike software languages, Spade does not have conditional execution. You do not conditionally assign values inside if expressiosn, you compute a value and return it.ies the number of bits, int<2>Type used to represent signed integers. The generic parameter (<N>) specifReturns the value of the first branch if the condition is true, otherwise the second branch.
Note that unlike software languages, Spade does not have conditional execution. You do not conditionally assign values inside if expressiosn, you compute a value and return it.ies the number of bits, boolType used to represent 1 bit values) = (a, b, c);

is represented as

logic x[10:0];
assign x = {a,b,c};

Binary representation

aaaaaaaabbc

Enums

Enums are packed with the leftmost bits being the discriminant and the remaining bits being the payload. The payload is packed left-to-right, meaning that the rightmost bits are undefined if a variant is smaller than the largest variant.

enum A {
    V1(a: int<8>Type used to represent signed integers. The generic parameter (<N>) specifReturns the value of the first branch if the condition is true, otherwise the second branch.
Note that unlike software languages, Spade does not have conditional execution. You do not conditionally assign values inside if expressiosn, you compute a value and return it.ies the number of bits),
    V2(b: int<2>Type used to represent signed integers. The generic parameter (<N>) specifReturns the value of the first branch if the condition is true, otherwise the second branch.
Note that unlike software languages, Spade does not have conditional execution. You do not conditionally assign values inside if expressiosn, you compute a value and return it.ies the number of bits),
    V3(c: boolType used to represent 1 bit values)
}

    9 8 7 6 5 4 3 2 1 0
    t t p p p p p p p p
    -------------------
V1: 0 0 a a a a a a a a
V2: 0 1 b b X X X X X X
V3: 1 0 c X X X X X X X

The Spade Hardware Description Language