chore: cononical order of mul_add return argument order

scroll-tech · Oct 4, 2024 · 0691494 · 0691494
1 parent 924d375
commit 0691494
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Showing 3 changed files with 8 additions and 12 deletions.
diff --git a/ceno_zkvm/src/instructions/riscv/divu.rs b/ceno_zkvm/src/instructions/riscv/divu.rs
@@ -44,7 +44,7 @@ impl<E: ExtensionField, I: RIVInstruction> Instruction<E> for ArithInstruction<E
         let mut outcome = UInt::new(|| "outcome", circuit_builder)?;
         let r = UInt::new(|| "remainder", circuit_builder)?;
 
-        let (inter_mul_value, dividend) =
+        let (dividend, inter_mul_value) =
             divisor.mul_add(|| "dividend", circuit_builder, &mut outcome, &r, true)?;
 
         // div by zero check

diff --git a/ceno_zkvm/src/instructions/riscv/shift_imm/shift_imm_circuit.rs b/ceno_zkvm/src/instructions/riscv/shift_imm/shift_imm_circuit.rs
@@ -43,7 +43,7 @@ impl<E: ExtensionField, I: RIVInstruction> Instruction<E> for ShiftImmInstructio
         // Goal is to constrain:
         // rs1 == rd_written * imm + remainder
         let remainder = UInt::new(|| "remainder", circuit_builder)?;
-        let (rd_imm_mul, rs1) = rd_written.mul_add(
+        let (rs1, rd_imm_mul) = rd_written.mul_add(
             || "rd_written * imm +remainder ",
             circuit_builder,
             &mut imm,
@@ -76,15 +76,14 @@ impl<E: ExtensionField, I: RIVInstruction> Instruction<E> for ShiftImmInstructio
         step: &StepRecord,
     ) -> Result<(), ZKVMError> {
         let rd_written = Value::new(step.rd().unwrap().value.after, lk_multiplicity);
-        let imm = Value::new(step.insn().imm_or_funct7(), lk_multiplicity);
 
-        // TODO design MulAdd gadget and refactor this to there
-        let remainder = {
+        let (remainder, imm) = {
             let rs1_read = step.rs1().unwrap().value;
             let imm = step.insn().imm_or_funct7();
-            let result = rs1_read.wrapping_div(imm);
-            let remainder = rs1_read.wrapping_sub(result * imm);
-            Value::new(remainder, lk_multiplicity)
+            (
+                Value::new(rs1_read % imm, lk_multiplicity),
+                Value::new(imm, lk_multiplicity),
+            )
         };
 
         let (rs1, rd_imm_mul) = rd_written.mul_add(&imm, &remainder, lk_multiplicity, true);

diff --git a/ceno_zkvm/src/uint/arithmetic.rs b/ceno_zkvm/src/uint/arithmetic.rs
@@ -271,10 +271,7 @@ impl<const M: usize, const C: usize, E: ExtensionField> UIntLimbs<M, C, E> {
     ) -> Result<(UIntLimbs<M, C, E>, UIntLimbs<M, C, E>), ZKVMError> {
         circuit_builder.namespace(name_fn, |cb| {
             let c = self.internal_mul(cb, multiplier, with_overflow, is_hi_limb)?;
-            Ok((
-                c.clone(),
-                c.internal_add(cb, &addend.expr(), with_overflow)?,
-            ))
+            Ok((c.internal_add(cb, &addend.expr(), with_overflow)?, c))
         })
     }