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select_ext takes bit as extension; used in recursive eval

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This commit is contained in:
Nicholas Ward 2021-07-27 22:51:40 -07:00
parent 33ba269ccb
commit a38a5e227d
2 changed files with 10 additions and 12 deletions
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16
src/gadgets/select.rs
View File

@ -10,24 +10,24 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
/// Note: This does not range-check `b`.
pub fn select_ext(
&mut self,
b: Target,
b: ExtensionTarget<D>,
x: ExtensionTarget<D>,
y: ExtensionTarget<D>,
) -> ExtensionTarget<D> {
let b_ext = self.convert_to_ext(b);
let gate = self.num_gates();
// Holds `by - y`.
let first_out =
ExtensionTarget::from_range(gate, ArithmeticExtensionGate::<D>::wires_first_output());
self.double_arithmetic_extension(F::ONE, F::NEG_ONE, b_ext, y, y, b_ext, x, first_out)
self.double_arithmetic_extension(F::ONE, F::NEG_ONE, b, y, y, b, x, first_out)
.1
}
/// See `select_ext`.
pub fn select(&mut self, b: Target, x: Target, y: Target) -> Target {
let b_ext = self.convert_to_ext(b);
let x_ext = self.convert_to_ext(x);
let y_ext = self.convert_to_ext(y);
self.select_ext(b, x_ext, y_ext).to_target_array()[0]
self.select_ext(b_ext, x_ext, y_ext).to_target_array()[0]
}
}
@ -54,13 +54,13 @@ mod tests {
let (x, y) = (FF::rand(), FF::rand());
let xt = builder.add_virtual_extension_target();
let yt = builder.add_virtual_extension_target();
let truet = builder.add_virtual_target();
let falset = builder.add_virtual_target();
let truet = builder.add_virtual_extension_target();
let falset = builder.add_virtual_extension_target();
pw.set_extension_target(xt, x);
pw.set_extension_target(yt, y);
pw.set_target(truet, F::ONE);
pw.set_target(falset, F::ZERO);
pw.set_extension_target(truet, FF::ONE);
pw.set_extension_target(falset, FF::ZERO);
let should_be_x = builder.select_ext(truet, xt, yt);
let should_be_y = builder.select_ext(falset, xt, yt);

6
src/gates/exponentiation.rs
View File

@ -171,9 +171,7 @@ impl<F: Extendable<D>, const D: usize> Gate<F, D> for ExponentiationGate<F, D> {
// power_bits is in LE order, but we accumulate in BE order.
let cur_bit = power_bits[self.num_power_bits - i - 1];
let not_cur_bit = builder.sub_extension(one, cur_bit);
let mul_by = builder.mul_add_extension(cur_bit, base, not_cur_bit);
let mul_by = builder.select_ext(cur_bit, base, one);
let computed_intermediate_value =
builder.mul_extension(prev_intermediate_value, mul_by);
let intermediate_value_diff =
@ -261,7 +259,7 @@ impl<F: Extendable<D>, const D: usize> SimpleGenerator<F> for ExponentiationGene
current_intermediate_value *= current_intermediate_value;
}
let mut result = GeneratedValues::<F>::with_capacity(num_power_bits);
let mut result = GeneratedValues::<F>::with_capacity(num_power_bits + 1);
for i in 0..num_power_bits {
let intermediate_value_wire = local_wire(self.gate.wires_intermediate_value(i));
result.set_wire(intermediate_value_wire, intermediate_values[i]);