1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226

use bus_mapping::circuit_input_builder::ChunkContext;
use gadgets::{
    is_zero::{IsZeroChip, IsZeroConfig, IsZeroInstruction},
    less_than::{LtChip, LtConfig},
    util::Expr,
};
use halo2_proofs::{
    circuit::{Layouter, Value},
    plonk::{Advice, Column, ConstraintSystem, Error, Expression, Instance, Selector},
    poly::Rotation,
};

use crate::{
    evm_circuit::util::rlc,
    table::{
        chunk_ctx_table::{ChunkCtxFieldTag, ChunkCtxTable},
        LookupTable,
    },
};
use eth_types::Field;
use gadgets::less_than::LtInstruction;

use super::Challenges;

/// chunk context config
#[derive(Clone, Debug)]
pub struct ChunkContextConfig<F> {
    chunk_index: Column<Advice>,
    chunk_index_next: Column<Advice>,
    total_chunks: Column<Advice>,
    q_chunk_context: Selector,

    /// is_first_chunk config
    pub is_first_chunk: IsZeroConfig<F>,
    /// is_last_chunk config
    pub is_last_chunk: IsZeroConfig<F>,

    /// ChunkCtxTable
    pub chunk_ctx_table: ChunkCtxTable,
    /// instance column for chunk context
    pub pi_chunk_ctx: Column<Instance>,

    /// Lt chip to check: chunk_index < total_chunks.
    /// Assume `total_chunks` < 2**8 = 256
    pub is_chunk_index_lt_total_chunks: LtConfig<F, 1>,
}

impl<F: Field> ChunkContextConfig<F> {
    /// new a chunk context config
    pub fn new(meta: &mut ConstraintSystem<F>, challenges: &Challenges<Expression<F>>) -> Self {
        let q_chunk_context = meta.complex_selector();
        let chunk_index = meta.advice_column();
        let chunk_index_inv = meta.advice_column();
        let chunk_index_next = meta.advice_column();
        let chunk_diff = meta.advice_column();
        let total_chunks = meta.advice_column();

        let pi_chunk_ctx = meta.instance_column();
        meta.enable_equality(pi_chunk_ctx);

        let chunk_ctx_table = ChunkCtxTable::construct(meta);
        chunk_ctx_table.annotate_columns(meta);

        [
            (ChunkCtxFieldTag::CurrentChunkIndex.expr(), chunk_index),
            (ChunkCtxFieldTag::NextChunkIndex.expr(), chunk_index_next),
            (ChunkCtxFieldTag::TotalChunks.expr(), total_chunks),
        ]
        .iter()
        .for_each(|(tag_expr, value_col)| {
            meta.lookup_any("chunk context lookup", |meta| {
                let q_chunk_context = meta.query_selector(q_chunk_context);
                let value_col_expr = meta.query_advice(*value_col, Rotation::cur());

                vec![(
                    q_chunk_context
                        * rlc::expr(
                            &[tag_expr.clone(), value_col_expr],
                            challenges.lookup_input(),
                        ),
                    rlc::expr(
                        &chunk_ctx_table.table_exprs(meta),
                        challenges.lookup_input(),
                    ),
                )]
            });
        });

        // assume max total_chunks < 2^8
        let is_chunk_index_lt_total_chunks = LtChip::<_, 1>::configure(
            meta,
            |meta| meta.query_selector(q_chunk_context),
            |meta| meta.query_advice(chunk_index, Rotation::cur()),
            |meta| meta.query_advice(total_chunks, Rotation::cur()),
        );

        meta.create_gate("chunk_index < total_chunks", |meta| {
            [meta.query_selector(q_chunk_context)
                * (1.expr() - is_chunk_index_lt_total_chunks.is_lt(meta, None))]
        });

        let is_first_chunk = IsZeroChip::configure(
            meta,
            |meta| meta.query_selector(q_chunk_context),
            |meta| meta.query_advice(chunk_index, Rotation::cur()),
            chunk_index_inv,
        );

        let is_last_chunk = IsZeroChip::configure(
            meta,
            |meta| meta.query_selector(q_chunk_context),
            |meta| {
                let chunk_index = meta.query_advice(chunk_index, Rotation::cur());
                let total_chunks = meta.query_advice(total_chunks, Rotation::cur());

                total_chunks - chunk_index - 1.expr()
            },
            chunk_diff,
        );

        Self {
            q_chunk_context,
            chunk_index,
            chunk_index_next,
            total_chunks,
            is_first_chunk,
            is_last_chunk,
            chunk_ctx_table,
            pi_chunk_ctx,
            is_chunk_index_lt_total_chunks,
        }
    }

    /// assign chunk context
    pub fn assign_chunk_context(
        &self,
        layouter: &mut impl Layouter<F>,
        chunk_context: &ChunkContext,
        max_offset_index: usize,
    ) -> Result<(), Error> {
        let is_chunk_index_lt_total_chunks = LtChip::construct(self.is_chunk_index_lt_total_chunks);
        is_chunk_index_lt_total_chunks.load(layouter)?;

        let (
            chunk_index_cell,
            chunk_index_next_cell,
            total_chunk_cell,
            initial_rwc_cell,
            end_rwc_cell,
        ) = self.chunk_ctx_table.load(layouter, chunk_context)?;

        let is_first_chunk = IsZeroChip::construct(self.is_first_chunk.clone());
        let is_last_chunk = IsZeroChip::construct(self.is_last_chunk.clone());
        layouter.assign_region(
            || "chunk context",
            |mut region| {
                region.name_column(|| "chunk_index", self.chunk_index);
                region.name_column(|| "chunk_index_next", self.chunk_index_next);
                region.name_column(|| "total_chunks", self.total_chunks);
                region.name_column(|| "pi_chunk_ctx", self.pi_chunk_ctx);
                self.is_first_chunk
                    .annotate_columns_in_region(&mut region, "is_first_chunk");
                self.is_last_chunk
                    .annotate_columns_in_region(&mut region, "is_last_chunk");
                self.chunk_ctx_table.annotate_columns_in_region(&mut region);

                for offset in 0..max_offset_index + 1 {
                    self.q_chunk_context.enable(&mut region, offset)?;

                    region.assign_advice(
                        || "chunk_index",
                        self.chunk_index,
                        offset,
                        || Value::known(F::from(chunk_context.idx as u64)),
                    )?;

                    region.assign_advice(
                        || "chunk_index_next",
                        self.chunk_index_next,
                        offset,
                        || Value::known(F::from(chunk_context.idx as u64 + 1u64)),
                    )?;

                    region.assign_advice(
                        || "total_chunks",
                        self.total_chunks,
                        offset,
                        || Value::known(F::from(chunk_context.total_chunks as u64)),
                    )?;

                    is_first_chunk.assign(
                        &mut region,
                        offset,
                        Value::known(F::from(chunk_context.idx as u64)),
                    )?;
                    is_last_chunk.assign(
                        &mut region,
                        offset,
                        Value::known(F::from(
                            (chunk_context.total_chunks - chunk_context.idx - 1) as u64,
                        )),
                    )?;
                    is_chunk_index_lt_total_chunks.assign(
                        &mut region,
                        offset,
                        Value::known(F::from(chunk_context.idx as u64)),
                        Value::known(F::from(chunk_context.total_chunks as u64)),
                    )?;
                }
                Ok(())
            },
        )?;

        [
            chunk_index_cell,
            chunk_index_next_cell,
            total_chunk_cell,
            initial_rwc_cell,
            end_rwc_cell,
        ]
        .iter()
        .enumerate()
        .try_for_each(|(i, cell)| layouter.constrain_instance(cell.cell(), self.pi_chunk_ctx, i))?;
        Ok(())
    }
}