mirror of
https://github.com/logos-storage/plonky2.git
synced 2026-02-13 18:33:27 +00:00
30c944f778
* Start removing bootstrapping * Change the constraint for kernel code initializing * Update specs * Apply comments * Add new global metadata to circuit methods * Change zero-initializing constraint * Apply comment * Update circuit size range for recursive test
82 lines
3.3 KiB
Rust
82 lines
3.3 KiB
Rust
use plonky2::field::extension::Extendable;
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use plonky2::field::packed::PackedField;
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use plonky2::hash::hash_types::RichField;
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use plonky2::iop::ext_target::ExtensionTarget;
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use crate::constraint_consumer::{ConstraintConsumer, RecursiveConstraintConsumer};
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use crate::cpu::columns::CpuColumnsView;
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/// General-purpose memory channels; they can read and write to all contexts/segments/addresses.
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pub(crate) const NUM_GP_CHANNELS: usize = 4;
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/// Indices for code and general purpose memory channels.
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pub mod channel_indices {
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use std::ops::Range;
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pub(crate) const CODE: usize = 0;
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pub(crate) const GP: Range<usize> = CODE + 1..(CODE + 1) + super::NUM_GP_CHANNELS;
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}
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/// Total memory channels used by the CPU table. This includes all the `GP_MEM_CHANNELS` as well as
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/// all special-purpose memory channels.
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///
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/// Currently, there is one special-purpose memory channel, which reads the opcode from memory. Its
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/// limitations are:
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/// - it is enabled by `is_cpu_cycle`,
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/// - it always reads and cannot write,
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/// - the context is derived from the current context and the `is_kernel_mode` flag,
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/// - the segment is hard-wired to the code segment,
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/// - the address is `program_counter`,
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/// - the value must fit in one byte (in the least-significant position) and its eight bits are
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/// found in `opcode_bits`.
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/// These limitations save us numerous columns in the CPU table.
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pub(crate) const NUM_CHANNELS: usize = channel_indices::GP.end;
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/// Evaluates constraints regarding the membus.
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pub(crate) fn eval_packed<P: PackedField>(
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lv: &CpuColumnsView<P>,
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yield_constr: &mut ConstraintConsumer<P>,
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) {
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// Validate `lv.code_context`.
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// It should be 0 if in kernel mode and `lv.context` if in user mode.
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yield_constr.constraint(lv.code_context - (P::ONES - lv.is_kernel_mode) * lv.context);
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// Validate `channel.used`. It should be binary.
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for channel in lv.mem_channels {
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yield_constr.constraint(channel.used * (channel.used - P::ONES));
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}
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// Validate `partial_channel.used`. It should be binary.
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yield_constr.constraint(lv.partial_channel.used * (lv.partial_channel.used - P::ONES));
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}
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/// Circuit version of `eval_packed`.
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/// Evaluates constraints regarding the membus.
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pub(crate) fn eval_ext_circuit<F: RichField + Extendable<D>, const D: usize>(
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builder: &mut plonky2::plonk::circuit_builder::CircuitBuilder<F, D>,
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lv: &CpuColumnsView<ExtensionTarget<D>>,
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yield_constr: &mut RecursiveConstraintConsumer<F, D>,
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) {
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// Validate `lv.code_context`.
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// It should be 0 if in kernel mode and `lv.context` if in user mode.
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let diff = builder.sub_extension(lv.context, lv.code_context);
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let constr = builder.mul_sub_extension(lv.is_kernel_mode, lv.context, diff);
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yield_constr.constraint(builder, constr);
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// Validate `channel.used`. It should be binary.
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for channel in lv.mem_channels {
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let constr = builder.mul_sub_extension(channel.used, channel.used, channel.used);
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yield_constr.constraint(builder, constr);
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}
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// Validate `partial_channel.used`. It should be binary.
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{
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let constr = builder.mul_sub_extension(
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lv.partial_channel.used,
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lv.partial_channel.used,
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lv.partial_channel.used,
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);
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yield_constr.constraint(builder, constr);
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}
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}
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