From cfb586c46b9cf255bbed19bf54a62957bbf53a1d Mon Sep 17 00:00:00 2001
From: Matthias Goergens <matthias.goergens@gmail.com>
Date: Mon, 9 Dec 2024 22:31:26 +0800
Subject: [PATCH] Round paranoid

---
 ceno_zkvm/src/tables/ram/ram_circuit.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ceno_zkvm/src/tables/ram/ram_circuit.rs b/ceno_zkvm/src/tables/ram/ram_circuit.rs
index 73c3862f7..1dc5e5afe 100644
--- a/ceno_zkvm/src/tables/ram/ram_circuit.rs
+++ b/ceno_zkvm/src/tables/ram/ram_circuit.rs
@@ -161,8 +161,9 @@ pub trait DynVolatileRamTable {
     fn name() -> &'static str;
 
     fn max_len(params: &ProgramParams) -> usize {
-        let max_size = (Self::end_addr(params) - Self::offset_addr(params)) as usize;
-        let max_len: usize = max_size.next_power_of_two().div_ceil(WORD_SIZE);
+        let max_size = (Self::end_addr(params) as usize).div_ceil(WORD_SIZE)
+            - (Self::offset_addr(params) as usize) / WORD_SIZE;
+        let max_len: usize = max_size.next_power_of_two();
         assert!(
             max_size <= max_len,
             "Did not round up {max_size} correctly, got {max_len}, which is smaller."