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Simplify insert and rotate gadgets, and check that we don't overrotate.

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This commit is contained in:
wborgeaud 2021-06-16 11:17:45 +02:00
parent 8d999ab299
commit e647e17720
3 changed files with 12 additions and 15 deletions
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10
src/gadgets/insert.rs
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@ -14,15 +14,9 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
element: ExtensionTarget<D>,
mut v: Vec<ExtensionTarget<D>>,
) -> Vec<ExtensionTarget<D>> {
let len = v.len();
let len_bits = bits_u64(len as u64);
let mut v = self.rotate_left(index, &v, len_bits);
let mut v = self.rotate_left(index, &v);
v.insert(0, element);
let len_bits = bits_u64(len as u64 + 1);
self.rotate_right(index, &v, len_bits)
self.rotate_right(index, &v)
}
}
#[cfg(test)]

14
src/gadgets/rotate.rs
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@ -2,7 +2,7 @@ use crate::circuit_builder::CircuitBuilder;
use crate::field::extension_field::target::ExtensionTarget;
use crate::field::extension_field::Extendable;
use crate::target::Target;
use crate::util::bits_u64;
use crate::util::log2_ceil;
impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
/// Selects `x` or `y` based on `b`, which is assumed to be binary.
@ -29,6 +29,7 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
v: &[ExtensionTarget<D>],
) -> Vec<ExtensionTarget<D>> {
let len = v.len();
debug_assert!(k < len, "Trying to rotate by more than the vector length.");
let mut res = Vec::new();
for i in 0..len {
@ -46,6 +47,7 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
v: &[ExtensionTarget<D>],
) -> Vec<ExtensionTarget<D>> {
let len = v.len();
debug_assert!(k < len, "Trying to rotate by more than the vector length.");
let mut res = Vec::new();
for i in 0..len {
@ -90,9 +92,8 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
&mut self,
num_rotation: Target,
v: &[ExtensionTarget<D>],
len_bits: usize,
) -> Vec<ExtensionTarget<D>> {
debug_assert_eq!(bits_u64(v.len() as u64), len_bits);
let len_bits = log2_ceil(v.len());
let bits = self.split_le(num_rotation, len_bits);
self.rotate_left_from_bits(&bits, v)
@ -102,9 +103,8 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
&mut self,
num_rotation: Target,
v: &[ExtensionTarget<D>],
len_bits: usize,
) -> Vec<ExtensionTarget<D>> {
debug_assert_eq!(bits_u64(v.len() as u64), len_bits);
let len_bits = log2_ceil(v.len());
let bits = self.split_le(num_rotation, len_bits);
self.rotate_right_from_bits(&bits, v)
@ -141,7 +141,7 @@ mod tests {
for i in 0..len {
let it = builder.constant(F::from_canonical_usize(i));
let rotated = real_rotate(i, &v);
let purported_rotated = builder.rotate_left(it, &v, bits_u64(len as u64));
let purported_rotated = builder.rotate_left(it, &v);
for (x, y) in rotated.into_iter().zip(purported_rotated) {
builder.assert_equal_extension(x, y);
@ -154,7 +154,7 @@ mod tests {
#[test]
fn test_rotate() {
for len in 1..6 {
for len in 1..5 {
test_rotate_given_len(len);
}
}

3
src/gadgets/split_join.rs
View File

@ -29,6 +29,9 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
/// Verifies that the decomposition is correct by using `k` `BaseSum<2>` gates
/// with `k` such that `k*num_routed_wires>=num_bits`.
pub(crate) fn split_le(&mut self, integer: Target, num_bits: usize) -> Vec<Target> {
if num_bits == 0 {
return Vec::new();
}
let num_limbs = self.config.num_routed_wires - BaseSumGate::<2>::START_LIMBS;
let k = ceil_div_usize(num_bits, num_limbs);
let gates = (0..k)