mirror of
https://github.com/logos-storage/plonky2.git
synced 2026-01-11 10:13:09 +00:00
e73d01a037
* `packed_field` -> `packed` For cleaner imports; "field" is usually clear from context * fix
77 lines
2.9 KiB
Rust
77 lines
2.9 KiB
Rust
use plonky2::field::extension::Extendable;
|
|
use plonky2::field::packed::PackedField;
|
|
use plonky2::field::types::{Field, PrimeField64};
|
|
use plonky2::hash::hash_types::RichField;
|
|
use plonky2::iop::ext_target::ExtensionTarget;
|
|
use plonky2::plonk::circuit_builder::CircuitBuilder;
|
|
use starky::constraint_consumer::{ConstraintConsumer, RecursiveConstraintConsumer};
|
|
|
|
use crate::registers::alu::*;
|
|
use crate::registers::NUM_COLUMNS;
|
|
|
|
pub(crate) fn generate_subtraction<F: PrimeField64>(values: &mut [F; NUM_COLUMNS]) {
|
|
let in_1 = values[COL_SUB_INPUT_0].to_canonical_u64() as u32;
|
|
let in_2 = values[COL_SUB_INPUT_1].to_canonical_u64() as u32;
|
|
|
|
// in_1 - in_2 == diff - br*2^32
|
|
let (diff, br) = in_1.overflowing_sub(in_2);
|
|
|
|
values[COL_SUB_OUTPUT_0] = F::from_canonical_u16(diff as u16);
|
|
values[COL_SUB_OUTPUT_1] = F::from_canonical_u16((diff >> 16) as u16);
|
|
values[COL_SUB_OUTPUT_BORROW] = F::from_bool(br);
|
|
}
|
|
|
|
pub(crate) fn eval_subtraction<F: Field, P: PackedField<Scalar = F>>(
|
|
local_values: &[P; NUM_COLUMNS],
|
|
yield_constr: &mut ConstraintConsumer<P>,
|
|
) {
|
|
let is_sub = local_values[IS_SUB];
|
|
let in_1 = local_values[COL_SUB_INPUT_0];
|
|
let in_2 = local_values[COL_SUB_INPUT_1];
|
|
let out_1 = local_values[COL_SUB_OUTPUT_0];
|
|
let out_2 = local_values[COL_SUB_OUTPUT_1];
|
|
let out_br = local_values[COL_SUB_OUTPUT_BORROW];
|
|
|
|
let base = F::from_canonical_u64(1 << 16);
|
|
let base_sqr = F::from_canonical_u64(1 << 32);
|
|
|
|
let out_br = out_br * base_sqr;
|
|
let lhs = (out_br + in_1) - in_2;
|
|
let rhs = out_1 + out_2 * base;
|
|
|
|
yield_constr.constraint(is_sub * (lhs - rhs));
|
|
|
|
// We don't need to check that out_br is in {0, 1} because it's
|
|
// checked by boolean::col_bit(0) in the ALU.
|
|
}
|
|
|
|
pub(crate) fn eval_subtraction_circuit<F: RichField + Extendable<D>, const D: usize>(
|
|
builder: &mut CircuitBuilder<F, D>,
|
|
local_values: &[ExtensionTarget<D>; NUM_COLUMNS],
|
|
yield_constr: &mut RecursiveConstraintConsumer<F, D>,
|
|
) {
|
|
let is_sub = local_values[IS_SUB];
|
|
let in_1 = local_values[COL_SUB_INPUT_0];
|
|
let in_2 = local_values[COL_SUB_INPUT_1];
|
|
let out_1 = local_values[COL_SUB_OUTPUT_0];
|
|
let out_2 = local_values[COL_SUB_OUTPUT_1];
|
|
let out_br = local_values[COL_SUB_OUTPUT_BORROW];
|
|
|
|
let base = builder.constant_extension(F::Extension::from_canonical_u64(1 << 16));
|
|
#[allow(unused)] // TODO
|
|
let base_sqr = builder.constant_extension(F::Extension::from_canonical_u64(1 << 32));
|
|
|
|
// lhs = (out_br + in_1) - in_2
|
|
let lhs = builder.add_extension(out_br, in_1);
|
|
let lhs = builder.sub_extension(lhs, in_2);
|
|
|
|
// rhs = out_1 + base * out_2
|
|
let rhs = builder.mul_add_extension(out_2, base, out_1);
|
|
|
|
// filtered_diff = is_sub * (lhs - rhs)
|
|
let diff = builder.sub_extension(lhs, rhs);
|
|
let filtered_diff = builder.mul_extension(is_sub, diff);
|
|
|
|
yield_constr.constraint(builder, filtered_diff);
|
|
}
|