From d6983951a4743be405b7cc21ff6ad8bde13290bf Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Tue, 21 Jun 2022 16:11:00 -0700
Subject: [PATCH] attempted fix

---
 evm/src/all_stark.rs           | 21 ++++++++++++++-------
 evm/src/memory/memory_stark.rs | 13 +++++++++----
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/evm/src/all_stark.rs b/evm/src/all_stark.rs
index 148fe528..b883398a 100644
--- a/evm/src/all_stark.rs
+++ b/evm/src/all_stark.rs
@@ -216,6 +216,8 @@ mod tests {
             cpu_stark.generate(&mut row);
             cpu_trace_rows.push(row);
         }
+        let mut current_cpu_index = 0;
+        let mut last_timestamp = memory_trace[memory::registers::TIMESTAMP].values[0];
         for i in 0..num_memory_ops {
             let mem_timestamp = memory_trace[memory::registers::TIMESTAMP].values[i];
             let clock = mem_timestamp;
@@ -223,20 +225,25 @@ mod tests {
                 .filter(|&o| memory_trace[memory::registers::is_memop(o)].values[i] == F::ONE)
                 .collect_vec()[0];
 
-            cpu_trace_rows[i][cpu::columns::uses_memop(op)] = F::ONE;
-            cpu_trace_rows[i][cpu::columns::CLOCK] = clock;
-            cpu_trace_rows[i][cpu::columns::memop_is_read(op)] =
+            cpu_trace_rows[current_cpu_index][cpu::columns::uses_memop(op)] = F::ONE;
+            cpu_trace_rows[current_cpu_index][cpu::columns::CLOCK] = clock;
+            cpu_trace_rows[current_cpu_index][cpu::columns::memop_is_read(op)] =
                 memory_trace[memory::registers::IS_READ].values[i];
-            cpu_trace_rows[i][cpu::columns::memop_addr_context(op)] =
+            cpu_trace_rows[current_cpu_index][cpu::columns::memop_addr_context(op)] =
                 memory_trace[memory::registers::ADDR_CONTEXT].values[i];
-            cpu_trace_rows[i][cpu::columns::memop_addr_segment(op)] =
+            cpu_trace_rows[current_cpu_index][cpu::columns::memop_addr_segment(op)] =
                 memory_trace[memory::registers::ADDR_SEGMENT].values[i];
-            cpu_trace_rows[i][cpu::columns::memop_addr_virtual(op)] =
+            cpu_trace_rows[current_cpu_index][cpu::columns::memop_addr_virtual(op)] =
                 memory_trace[memory::registers::ADDR_VIRTUAL].values[i];
             for j in 0..8 {
-                cpu_trace_rows[i][cpu::columns::memop_value(op, j)] =
+                cpu_trace_rows[current_cpu_index][cpu::columns::memop_value(op, j)] =
                     memory_trace[memory::registers::value_limb(j)].values[i];
             }
+
+            if mem_timestamp != last_timestamp {
+                current_cpu_index += 1;
+                last_timestamp = mem_timestamp;
+            }
         }
         trace_rows_to_poly_values(cpu_trace_rows)
     }
diff --git a/evm/src/memory/memory_stark.rs b/evm/src/memory/memory_stark.rs
index 244af688..4de666d2 100644
--- a/evm/src/memory/memory_stark.rs
+++ b/evm/src/memory/memory_stark.rs
@@ -49,11 +49,9 @@ pub fn generate_random_memory_ops<F: RichField, R: Rng>(
 
     let mut current_memory_values: HashMap<(F, F, F), [F; 8]> = HashMap::new();
     for i in 0..num_ops {
-        let is_read = if i == 0 { false } else { rng.gen() };
-        let is_read_field = F::from_bool(is_read);
-
         let timestamp = F::from_canonical_usize(i);
         let mut used_indices = HashSet::new();
+        let mut new_writes_this_cycle = HashSet::new();
         for _ in 0..2 {
             let mut channel_index = rng.gen_range(0..4);
             while used_indices.contains(&channel_index) {
@@ -61,6 +59,9 @@ pub fn generate_random_memory_ops<F: RichField, R: Rng>(
             }
             used_indices.insert(channel_index);
 
+            let is_read = if i == 0 { false } else { rng.gen() };
+            let is_read_field = F::from_bool(is_read);
+
             let (context, segment, virt, vals) = if is_read {
                 let written: Vec<_> = current_memory_values.keys().collect();
                 let &(context, segment, virt) = written[rng.gen_range(0..written.len())];
@@ -79,7 +80,7 @@ pub fn generate_random_memory_ops<F: RichField, R: Rng>(
                 let val: [u32; 8] = rng.gen();
                 let vals: [F; 8] = val.map(F::from_canonical_u32);
 
-                current_memory_values.insert((context, segment, virt), vals);
+                new_writes_this_cycle.insert(((context, segment, virt), vals));
 
                 (context, segment, virt, vals)
             };
@@ -94,6 +95,10 @@ pub fn generate_random_memory_ops<F: RichField, R: Rng>(
                 value: vals,
             });
         }
+        for (k, v) in new_writes_this_cycle {
+            current_memory_values.insert(k, v);
+        }
+
     }
 
     memory_ops