straus_plookup_table computes a plookup-based lookup table of size 1 << table_bits More...

#include <straus_plookup_table.hpp>

Classes
struct	PrecomputedData
	Precomputed data for two-phase construction. Contains all data computed without builder access. More...

Public Types
using	field_t = stdlib::field_t< Builder >

using	bool_t = stdlib::bool_t< Builder >

using	Curve = typename Builder::EmbeddedCurve

using	Group = typename Curve::Group

using	Element = typename Curve::Element

using	AffineElement = typename Curve::AffineElement

Public Member Functions
	straus_plookup_table ()=default

	straus_plookup_table (Builder *context, const AffineElement &base_point, const AffineElement &offset_generator, size_t table_bits)
	Construct a plookup-based Straus lookup table for a constant base point.

	straus_plookup_table (Builder *context, PrecomputedData data)
	Construct from precomputed data — serial Phase 2, only touches the circuit builder.

cycle_group< Builder >	read (const field_t &index)
	Read from the plookup table at the given index.

const std::vector< AffineElement > &	get_native_table () const

Static Public Member Functions
static PrecomputedData	build_precomputed_data (const AffineElement &base_point, const AffineElement &offset_generator, size_t table_bits)
	Compute native table entries and BasicTable column data without touching the circuit builder.

Private Attributes
Builder *	_context = nullptr

plookup::BasicTable *	_table = nullptr

std::vector< AffineElement >	native_table

OriginTag	tag

Detailed Description

template<typename Builder>
class bb::stdlib::straus_plookup_table< Builder >

straus_plookup_table computes a plookup-based lookup table of size 1 << table_bits

For a CONSTANT base_point [P] and offset_generator point [G], where N = 1 << table_bits, the following is computed:

{ [G] + 0.[P], [G] + 1.[P], ..., [G] + (N - 1).[P] }

Unlike straus_lookup_table (which uses ROM tables), this class creates plookup BasicTable entries. Plookup tables have zero construction cost (table data is part of the proving polynomial) and each read costs exactly 1 lookup gate with no finalization overhead. This makes them significantly cheaper than ROM tables for fixed/constant base points.

Note: This class requires the base point to be a circuit constant (not a witness). For witness base points, use straus_lookup_table instead.; The offset generator [G] prevents point-at-infinity edge cases, same as in straus_lookup_table.

Definition at line 31 of file straus_plookup_table.hpp.

Member Typedef Documentation

◆ AffineElement

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::AffineElement = typename Curve::AffineElement

Definition at line 38 of file straus_plookup_table.hpp.

◆ bool_t

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::bool_t = stdlib::bool_t<Builder>

Definition at line 34 of file straus_plookup_table.hpp.

◆ Curve

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::Curve = typename Builder::EmbeddedCurve

Definition at line 35 of file straus_plookup_table.hpp.

◆ Element

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::Element = typename Curve::Element

Definition at line 37 of file straus_plookup_table.hpp.

◆ field_t

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::field_t = stdlib::field_t<Builder>

Definition at line 33 of file straus_plookup_table.hpp.

◆ Group

template<typename Builder >

using bb::stdlib::straus_plookup_table< Builder >::Group = typename Curve::Group

Definition at line 36 of file straus_plookup_table.hpp.

Constructor & Destructor Documentation

◆ straus_plookup_table() [1/3]

template<typename Builder >

bb::stdlib::straus_plookup_table< Builder >::straus_plookup_table ( )

default

◆ straus_plookup_table() [2/3]

template<typename Builder >

bb::stdlib::straus_plookup_table< Builder >::straus_plookup_table	(	Builder *	context,
		const AffineElement &	base_point,
		const AffineElement &	offset_generator,
		size_t	table_bits
	)

Construct a plookup-based Straus lookup table for a constant base point.

Creates a BasicTable with (1 << table_bits) entries of the form: { offset_generator + i * base_point } for i in [0, 1 << table_bits)

The table is pushed directly into the builder's lookup_tables deque. Table data becomes part of the proving polynomial (zero gate cost). Each subsequent read costs exactly 1 lookup gate.

Parameters

context	The circuit builder
base_point	Constant base point (must not be a witness)
offset_generator	Offset to prevent point-at-infinity edge cases
table_bits	Number of bits per table (table has 1 << table_bits entries)

Definition at line 95 of file straus_plookup_table.cpp.

◆ straus_plookup_table() [3/3]

template<typename Builder >

bb::stdlib::straus_plookup_table< Builder >::straus_plookup_table	(	Builder *	context,
		PrecomputedData	data
	)

Construct from precomputed data — serial Phase 2, only touches the circuit builder.

Assigns table_index and pushes the BasicTable into the builder's lookup_tables deque. Must be called serially (builder is not thread-safe).

Parameters

context	The circuit builder
data	Precomputed native table + BasicTable columns

Definition at line 70 of file straus_plookup_table.cpp.

Member Function Documentation

◆ build_precomputed_data()

template<typename Builder >

straus_plookup_table< Builder >::PrecomputedData bb::stdlib::straus_plookup_table< Builder >::build_precomputed_data	(	const AffineElement &	base_point,
		const AffineElement &	offset_generator,
		size_t	table_bits
	)

static

Compute native table entries and BasicTable column data without touching the circuit builder.

This is the parallelizable part of table construction. It builds:

native_table: affine points { offset_generator + i * base_point } for i in [0, table_size)
basic_table: a BasicTable with columns populated but table_index NOT yet assigned

Parameters

base_point	Constant base point
offset_generator	Offset to prevent point-at-infinity edge cases
table_bits	Number of bits per table (table has 1 << table_bits entries)

Returns: PrecomputedData Contains native_table and basic_table (without table_index)

Definition at line 20 of file straus_plookup_table.cpp.

◆ get_native_table()

template<typename Builder >

const std::vector< AffineElement > & bb::stdlib::straus_plookup_table< Builder >::get_native_table ( ) const

inline

Definition at line 63 of file straus_plookup_table.hpp.

◆ read()

template<typename Builder >

cycle_group< Builder > bb::stdlib::straus_plookup_table< Builder >::read ( const field_t & _index )

Read from the plookup table at the given index.

Creates a single lookup gate constraining (index, x, y) to a valid row in this table. The index witness is reused as the lookup key so the scalar slice is directly constrained.

Parameters

_index The lookup index (witness or constant, typically a scalar slice)

Returns: cycle_group<Builder> The point at native_table[index]

Definition at line 111 of file straus_plookup_table.cpp.

Member Data Documentation

◆ _context

template<typename Builder >

Builder* bb::stdlib::straus_plookup_table< Builder >::_context = nullptr

private

Definition at line 66 of file straus_plookup_table.hpp.

◆ _table

template<typename Builder >

plookup::BasicTable* bb::stdlib::straus_plookup_table< Builder >::_table = nullptr

private

Definition at line 67 of file straus_plookup_table.hpp.

◆ native_table

template<typename Builder >

std::vector<AffineElement> bb::stdlib::straus_plookup_table< Builder >::native_table

private

Definition at line 68 of file straus_plookup_table.hpp.

◆ tag

template<typename Builder >

OriginTag bb::stdlib::straus_plookup_table< Builder >::tag

private

Definition at line 69 of file straus_plookup_table.hpp.

The documentation for this class was generated from the following files:

src/barretenberg/stdlib/primitives/group/straus_plookup_table.hpp
src/barretenberg/stdlib/primitives/group/straus_plookup_table.cpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Private Attributes

Detailed Description

Member Typedef Documentation

◆ AffineElement

◆ bool_t

◆ Curve

◆ Element

◆ field_t

◆ Group

Constructor & Destructor Documentation

◆ straus_plookup_table() [1/3]

◆ straus_plookup_table() [2/3]

◆ straus_plookup_table() [3/3]

Member Function Documentation

◆ build_precomputed_data()

◆ get_native_table()

◆ read()

Member Data Documentation

◆ _context

◆ _table

◆ native_table

◆ tag