sp1_core_machine/control_flow/branch/
columns.rs

1use sp1_derive::AlignedBorrow;
2use sp1_stark::Word;
3use std::mem::size_of;
4
5use crate::operations::BabyBearWordRangeChecker;
6
7pub const NUM_BRANCH_COLS: usize = size_of::<BranchColumns<u8>>();
8
9/// The column layout for branching.
10#[derive(AlignedBorrow, Default, Debug, Clone, Copy)]
11#[repr(C)]
12pub struct BranchColumns<T> {
13    /// The current program counter.
14    pub pc: Word<T>,
15    pub pc_range_checker: BabyBearWordRangeChecker<T>,
16
17    /// The next program counter.
18    pub next_pc: Word<T>,
19    pub next_pc_range_checker: BabyBearWordRangeChecker<T>,
20
21    /// The value of the first operand.
22    pub op_a_value: Word<T>,
23    /// The value of the second operand.
24    pub op_b_value: Word<T>,
25    /// The value of the third operand.
26    pub op_c_value: Word<T>,
27
28    /// Whether the first operand is register 0.
29    pub op_a_0: T,
30
31    /// Branch Instructions.
32    pub is_beq: T,
33    pub is_bne: T,
34    pub is_blt: T,
35    pub is_bge: T,
36    pub is_bltu: T,
37    pub is_bgeu: T,
38
39    /// The is_branching column is equal to:
40    ///
41    /// > is_beq & a_eq_b ||
42    /// > is_bne & (a_lt_b | a_gt_b) ||
43    /// > (is_blt | is_bltu) & a_lt_b ||
44    /// > (is_bge | is_bgeu) & (a_eq_b | a_gt_b)
45    pub is_branching: T,
46
47    /// The not branching column is equal to:
48    ///
49    /// > is_beq & !a_eq_b ||
50    /// > is_bne & !(a_lt_b | a_gt_b) ||
51    /// > (is_blt | is_bltu) & !a_lt_b ||
52    /// > (is_bge | is_bgeu) & !(a_eq_b | a_gt_b)
53    ///
54    /// Note that we probably can do away with this column and just use !is_branching.
55    /// However, the branching related constraints were auditted twice when they were part of the
56    /// CPU table, so I'm preserving those columns/constraints for now.
57    pub not_branching: T,
58
59    /// Whether a equals b.
60    pub a_eq_b: T,
61
62    /// Whether a is greater than b.
63    pub a_gt_b: T,
64
65    /// Whether a is less than b.
66    pub a_lt_b: T,
67}
sp1_core_machine/control_flow/branch/columns.rs

sp1_core_machine/control_flow/branch/
columns.rs
