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Added dynamic array abstraction into standard library (#112)
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Implements RAM/ROM stuff and dynamic arrays as well as separated all fixed_base operation in standard plonk into a separate file, so that it is no longer part of composer
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@zac-williamson
zac-williamson authored Mar 18, 2023
1 parent f2f8d1f commit 24ab0dc
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3 changes: 3 additions & 0 deletions cpp/.gitignore
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Expand Up @@ -5,3 +5,6 @@ src/barretenberg/proof_system/proving_key/fixtures
src/barretenberg/rollup/proofs/*/fixtures
srs_db/*/*/transcript*
CMakeUserPresets.json
.vscode/settings.json
# to be unignored when we agree on clang-tidy rules
.clangd
240 changes: 0 additions & 240 deletions cpp/src/barretenberg/honk/circuit_constructors/standard_circuit_constructor.cpp
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Expand Up @@ -250,246 +250,6 @@ void StandardCircuitConstructor::create_poly_gate(const poly_triple& in)
++num_gates;
}

void StandardCircuitConstructor::create_fixed_group_add_gate_with_init(const fixed_group_add_quad& in,
const fixed_group_init_quad& init)
{
uint32_t x_0_idx = in.a;
uint32_t y_0_idx = in.b;
uint32_t x_alpha_idx = in.c;
uint32_t a_0_idx = in.d;

fr x_alpha = get_variable(x_alpha_idx);
fr a_0 = get_variable(a_0_idx);

// weird names here follow the Turbo notation
fr q_4 = init.q_x_1;
fr q_5 = init.q_x_2;
fr q_m = init.q_y_1;
fr q_c = init.q_y_2;

// We will think of s = 1-a_0 as an auxiliary "switch" which is equal to either -x_alpha or 0
// during the initialization step, but we will not add this variable to the composer for reasons of efficiency.

// (ɑ^4 identity) impose 1-a_0 = 0 or -x_alpha
// // first check formula for sx_alpha
fr sx_alpha = (fr(1) - a_0) * x_alpha;
uint32_t sx_alpha_idx = add_variable(sx_alpha);
create_poly_gate(
{ .a = a_0_idx, .b = x_alpha_idx, .c = sx_alpha_idx, .q_m = 1, .q_l = 0, .q_r = -1, .q_o = 1, .q_c = 0 });

// // now add the desired constraint on sx_alpha
// // s(s + x_alpha) = s*s + s*x_alpha = 0
create_poly_gate(
{ .a = a_0_idx, .b = a_0_idx, .c = sx_alpha_idx, .q_m = 1, .q_l = -2, .q_r = 0, .q_o = 1, .q_c = 1 });

// (ɑ^5 identity)
create_poly_gate(
{ .a = x_0_idx, .b = x_alpha_idx, .c = a_0_idx, .q_m = -1, .q_l = 0, .q_r = q_4, .q_o = -q_5, .q_c = q_5 });

// (ɑ^6 identity)
create_poly_gate(
{ .a = y_0_idx, .b = x_alpha_idx, .c = a_0_idx, .q_m = -1, .q_l = 0, .q_r = q_m, .q_o = -q_c, .q_c = q_c });

// There is no previous add quad.
previous_add_quad = in;
}

void StandardCircuitConstructor::create_fixed_group_add_gate(const fixed_group_add_quad& in)
{
assert_valid_variables({ in.a, in.b, in.c, in.d });

auto row_1 = previous_add_quad;
auto row_2 = in;
previous_add_quad = in;

fr a_1 = get_variable(row_1.d);
fr a_2 = get_variable(row_2.d);
fr x_1 = get_variable(row_1.a);
fr y_1 = get_variable(row_1.b);
fr x_2 = get_variable(row_2.a);
fr y_2 = get_variable(row_2.b);
fr x_alpha = get_variable(row_2.c);

fr q_x_alpha_1 = row_1.q_x_1;
fr q_x_alpha_2 = row_1.q_x_2;
fr q_y_alpha_1 = row_1.q_y_1;
fr q_y_alpha_2 = row_1.q_y_2;

uint32_t a_1_idx = row_1.d;
uint32_t a_2_idx = row_2.d;
uint32_t x_1_idx = row_1.a;
uint32_t y_1_idx = row_1.b;
uint32_t x_2_idx = row_2.a;
uint32_t y_2_idx = row_2.b;
uint32_t x_alpha_idx = row_2.c;

// add variable δ = a_2 - 4a_1
fr delta = a_2 - (a_1 + a_1 + a_1 + a_1);
uint32_t delta_idx = add_variable(delta);
create_add_gate({ .a = a_2_idx,
.b = a_1_idx,
.c = delta_idx,
.a_scaling = 1,
.b_scaling = -4,
.c_scaling = -1,
.const_scaling = 0 });

// constraint: (δ + 3)(δ + 1)(δ - 1)(δ - 3)
// (δ + 3)(δ + 1)(δ - 1)(δ - 3) = (δ^2 - 9)(δ^2 - 1)=0
// // first: (δ^2 - δ_sqr = 0)
fr delta_sqr = delta * delta;
uint32_t delta_sqr_idx = add_variable(delta_sqr);
create_mul_gate(
{ .a = delta_idx, .b = delta_idx, .c = delta_sqr_idx, .mul_scaling = 1, .c_scaling = -1, .const_scaling = 0 });
// // next (δ^2 - 9)( δ^2 - 1) = δ^2*δ^2 - 10 * δ^2 + 9 = 0
create_mul_gate({ .a = delta_sqr_idx,
.b = delta_sqr_idx,
.c = delta_sqr_idx,
.mul_scaling = 1,
.c_scaling = -10,
.const_scaling = 9 });

// validate correctness of x_ɑ
// constraint: (δ^2) * q_x_ɑ,1 + q_x_ɑ,2 - x,ɑ = 0
create_add_gate({ .a = delta_sqr_idx,
.b = x_alpha_idx,
.c = zero_idx,
.a_scaling = q_x_alpha_1,
.b_scaling = -1,
.c_scaling = 0,
.const_scaling = q_x_alpha_2 });

// compute y_alpha using lookup formula, instantiate as witness and validate
fr y_alpha = (x_alpha * q_y_alpha_1 + q_y_alpha_2) * delta;
uint32_t y_alpha_idx = add_variable(y_alpha);
create_poly_gate({ .a = delta_idx,
.b = x_alpha_idx,
.c = y_alpha_idx,
.q_m = q_y_alpha_1,
.q_l = q_y_alpha_2,
.q_r = 0,
.q_o = -1,
.q_c = 0 });

// show that (x_1, y_1) + (x_ɑ, y_ɑ) = (x_2, y_2) in 11 gates
// // 4 gates to compute commonly used expressions
// // // 2 differences:
fr diff_x_alpha_x_1 = x_alpha - x_1;
uint32_t diff_x_alpha_x_1_idx = add_variable(diff_x_alpha_x_1);
create_add_gate({ .a = diff_x_alpha_x_1_idx,
.b = x_1_idx,
.c = x_alpha_idx,
.a_scaling = 1,
.b_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

fr diff_y_alpha_y_1 = y_alpha - y_1;
uint32_t diff_y_alpha_y_1_idx = add_variable(diff_y_alpha_y_1);
create_add_gate({ .a = diff_y_alpha_y_1_idx,
.b = y_1_idx,
.c = y_alpha_idx,
.a_scaling = 1,
.b_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

// // // now the squares of these 2 differences
fr diff_x_alpha_x_1_sqr = diff_x_alpha_x_1 * diff_x_alpha_x_1;
uint32_t diff_x_alpha_x_1_sqr_idx = add_variable(diff_x_alpha_x_1_sqr);
create_mul_gate({ .a = diff_x_alpha_x_1_idx,
.b = diff_x_alpha_x_1_idx,
.c = diff_x_alpha_x_1_sqr_idx,
.mul_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

fr diff_y_alpha_y_1_sqr = diff_y_alpha_y_1 * diff_y_alpha_y_1;
uint32_t diff_y_alpha_y_1_sqr_idx = add_variable(diff_y_alpha_y_1_sqr);
create_mul_gate({ .a = diff_y_alpha_y_1_idx,
.b = diff_y_alpha_y_1_idx,
.c = diff_y_alpha_y_1_sqr_idx,
.mul_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

// // 3 gates to build identity for x_2
// // // compute x_2 + x_ɑ + x_1 using 2 poly_gates via create_big_add_gate
fr sum_x_1_2_alpha = x_2 + x_alpha + x_1;
uint32_t sum_x_1_2_alpha_idx = add_variable(sum_x_1_2_alpha);
create_big_add_gate({ .a = x_2_idx,
.b = x_alpha_idx,
.c = x_1_idx,
.d = sum_x_1_2_alpha_idx,
.a_scaling = 1,
.b_scaling = 1,
.c_scaling = 1,
.d_scaling = -1,
.const_scaling = 0 });

// // // constraint: identity for x_2
create_poly_gate({ .a = sum_x_1_2_alpha_idx,
.b = diff_x_alpha_x_1_sqr_idx,
.c = diff_y_alpha_y_1_sqr_idx,
.q_m = 1,
.q_l = 0,
.q_r = 0,
.q_o = -1,
.q_c = 0 });

// // 4 gates to build identity for y_2:
// // // 3 auxiliary
fr sum_y_1_y_2 = y_1 + y_2;
uint32_t sum_y_1_y_2_idx = add_variable(sum_y_1_y_2);
create_add_gate({ .a = y_1_idx,
.b = y_2_idx,
.c = sum_y_1_y_2_idx,
.a_scaling = 1,
.b_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

fr diff_x_1_x_2 = x_1 - x_2;
uint32_t diff_x_1_x_2_idx = add_variable(diff_x_1_x_2);
create_add_gate({ .a = diff_x_1_x_2_idx,
.b = x_2_idx,
.c = x_1_idx,
.a_scaling = 1,
.b_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

fr prod_y_diff_x_diff = diff_y_alpha_y_1 * diff_x_1_x_2;
uint32_t prod_y_diff_x_diff_idx = add_variable(prod_y_diff_x_diff);
create_mul_gate({ .a = diff_y_alpha_y_1_idx,
.b = diff_x_1_x_2_idx,
.c = prod_y_diff_x_diff_idx,
.mul_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });

// // // identity for y_2
create_mul_gate({ .a = sum_y_1_y_2_idx,
.b = diff_x_alpha_x_1_idx,
.c = prod_y_diff_x_diff_idx,
.mul_scaling = 1,
.c_scaling = -1,
.const_scaling = 0 });
}

void StandardCircuitConstructor::create_fixed_group_add_gate_final(const add_quad& in)
{
fixed_group_add_quad final_round_quad{ .a = in.a,
.b = in.b,
.c = in.c,
.d = in.d,
.q_x_1 = fr::zero(),
.q_x_2 = fr::zero(),
.q_y_1 = fr::zero(),
.q_y_2 = fr::zero() };
create_fixed_group_add_gate(final_round_quad);
}

std::vector<uint32_t> StandardCircuitConstructor::decompose_into_base4_accumulators(const uint32_t witness_index,
const size_t num_bits,
std::string const& msg)
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