[#1793] Outline column structure for FFMul in serialization

o1-labs · Mar 28, 2024 · 4ab1b42 · 4ab1b42
1 parent 7273015
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Showing 2 changed files with 44 additions and 10 deletions.
diff --git a/msm/src/serialization/column.rs b/msm/src/serialization/column.rs
@@ -4,15 +4,29 @@ use crate::{
     N_LIMBS,
 };
 
+/// Total number of columns in the serialization circuit
+pub const SER_N_COLUMNS: usize = 6 * N_LIMBS + N_INTERMEDIATE_LIMBS + 9;
+
 /// Column used by the serialization subcircuit
 /// It is not used yet.
 pub enum SerializationColumn {
-    /// 3 88 bits inputs
+    /// 3 88 bits inputs. For the row #i this represents the IPA challenge xi_{log(i)}.
     KimchiLimb(usize),
-    /// N_LIMBS values, representing the limbs used by the MSM
-    MSMLimb(usize),
     /// N_INTERMEDIATE_LIMBS intermediate values, 4 bits long.
     IntermediateLimb(usize),
+    /// N_LIMBS values, representing the limbs used by the MSM
+    MSMLimb(usize),
+    /// Previous C_j, this one is looked up. For the row i, the expected
+    /// value is (C_i >> 1).
+    CoeffInput(usize),
+    /// Trusted (for range) foreign field modulus, in 4 big limbs.
+    FFieldModulus(usize),
+    /// Quotient limbs
+    Quotient(usize),
+    /// Carry limbs
+    Carry(usize),
+    /// The resulting coefficient C_i = (C_i >> 1) * xi_{log(i)}. In small limbs.
+    CoeffResult(usize),
 }
 
 impl ColumnIndexer for SerializationColumn {
@@ -22,13 +36,33 @@ impl ColumnIndexer for SerializationColumn {
                 assert!(j < 3);
                 Column::X(j)
             }
+            Self::IntermediateLimb(j) => {
+                assert!(j < N_INTERMEDIATE_LIMBS);
+                Column::X(3 + j)
+            }
             Self::MSMLimb(j) => {
                 assert!(j < N_LIMBS);
-                Column::X(j + 3)
+                Column::X(N_INTERMEDIATE_LIMBS + 3 + j)
             }
-            Self::IntermediateLimb(j) => {
-                assert!(j < N_INTERMEDIATE_LIMBS);
-                Column::X(j + N_LIMBS + 3)
+            Self::CoeffInput(j) => {
+                assert!(j < N_LIMBS);
+                Column::X(N_INTERMEDIATE_LIMBS + N_LIMBS + 3 + j)
+            }
+            Self::FFieldModulus(j) => {
+                assert!(j < 4);
+                Column::X(N_INTERMEDIATE_LIMBS + 2 * N_LIMBS + 3 + j)
+            }
+            Self::Quotient(j) => {
+                assert!(j < N_LIMBS);
+                Column::X(N_INTERMEDIATE_LIMBS + 2 * N_LIMBS + 7 + j)
+            }
+            Self::Carry(j) => {
+                assert!(j < 2 * N_LIMBS + 2);
+                Column::X(N_INTERMEDIATE_LIMBS + 3 * N_LIMBS + 7 + j)
+            }
+            Self::CoeffResult(j) => {
+                assert!(j < N_LIMBS);
+                Column::X(N_INTERMEDIATE_LIMBS + 5 * N_LIMBS + 9 + j)
             }
         }
     }

diff --git a/msm/src/serialization/mod.rs b/msm/src/serialization/mod.rs
@@ -1,13 +1,13 @@
 use crate::{mvlookup::LookupTableID, MVLookup};
 
-/// The number of intermediate limbs of 4 bits required for the circuit
-pub const N_INTERMEDIATE_LIMBS: usize = 20;
-
 pub mod column;
 pub mod constraints;
 pub mod interpreter;
 pub mod witness;
 
+/// The number of intermediate limbs of 4 bits required for the circuit
+pub const N_INTERMEDIATE_LIMBS: usize = 20;
+
 #[derive(Clone, Copy, Debug)]
 pub enum LookupTable {
     RangeCheck15,