Sootty provides a temporal-logic language that is used to define the bounds of the displayed window. This language can select points in time within time-series data. Each expression represents the value of a n-bit vector over time. The language allows for both combinational expressions that are time-independent and some temporal expressions, including from, after, until, etc., that are time-dependent. The selected points in time for a given expression are defined as following each rising edge of the wire. When only a single point is needed, the first rising edge is used and the rest are discarded.
The grammar for the temporal logic expression is described below:
exp ∈ Expression := wire | type num | unop exp | exp binop exp | timeop exp
wire ∈ Identifier (e.g., clk, data, ...)
type ∈ Types := const | time
num ∈ Number (e.g., 0, 1, 2, ...)
unop ∈ UnaryOps := ! | - | ~
binop ∈ BinaryOps := & | | | && | || | ^ | == | != | > | >= | < | <= | << | >> | + | - | %
timeop ∈ TimeOps := from | after | until | before | next | prev | num next | num prev | acc
x — A wire with pre-defined values at each point in time.
time 4 — A wire with value 0 from until time 3, and value 1 from time 4 and after.
const 5 — A wire with a constant value of 5 at all points in time.
x == const 5 — A wire with value 1 during all points when the value of x equals 5, and a 0 otherwise.
x & y — A wire defined as the bitwise and of the values of x and y at each point in time.
x ^ y — A wire defined as the bitwise xor of the values of x and y at each point in time.
x && y — A wire defined as the logical and of the values of x and y at each point in time.
x || y — A wire defined as the logical or of the values of x and y at each point in time.
x << const 1 — A wire defined as the values of x shifted left by 1 at each point in time.
from x — A wire with value 1 for all points including and after the first rising edge of x, and value 0 otherwise.
after x — A wire with value 1 for all points after the first rising edge of x, and value 0 otherwise.
until x — A wire with value 1 for all points including and before the first rising edge of x, and value 0 otherwise.
before x — A wire with value 1 for all points after the first rising edge of x, and value 0 otherwise.
next x — A wire with the value of x at time t+1 shifted to time t.
3 prev x — A wire with the value of x at time t-3 shifted to time t.
acc clk — A wire with a value equal to the number of rising edges of clk before each point in time. (The accumulated sum of values)
The operator precendence defined in the grammar is as follows in descending order.
- Parentheses —
() - Unary operators —
!|~|- - Modulus —
% - Add, Subtract —
+|- - Left Shift, Right Shift —
<<|>> - Bitwise operators —
&|||^ - Relational operators —
==|!=|>|>=|<|<= - Logical operators —
&&|||