From c4b511baf457933adc315a7ebad3a0c2e0fa3e2a Mon Sep 17 00:00:00 2001
From: Nicholas Ward <npward@berkeley.edu>
Date: Tue, 14 Mar 2023 14:28:21 -0700
Subject: [PATCH] addressed comments

---
 evm/src/cpu/kernel/asm/bignum/shr.asm | 10 ++++++++++
 evm/src/cpu/kernel/interpreter.rs     |  4 +++-
 evm/src/cpu/kernel/tests/bignum.rs    |  2 +-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/evm/src/cpu/kernel/asm/bignum/shr.asm b/evm/src/cpu/kernel/asm/bignum/shr.asm
index 5e3a56ef..399b372e 100644
--- a/evm/src/cpu/kernel/asm/bignum/shr.asm
+++ b/evm/src/cpu/kernel/asm/bignum/shr.asm
@@ -4,6 +4,11 @@
 // Shifts a given bignum right by one bit (in place).
 // Assumes that len > 0.
 global shr_bignum:
+    // stack: len, start_loc, retdest
+    DUP1
+    // stack: len, len, start_loc, retdest
+    ISZERO
+    %jumpi(shr_end_len_zero)
     // stack: len, start_loc, retdest
     DUP2
     // stack: start_loc, len, start_loc, retdest
@@ -55,3 +60,8 @@ shr_end:
     %pop3
     // stack: retdest
     JUMP
+shr_end_len_zero:
+    // stack: len, start_loc, retdest
+    %pop2
+    // stack: retdest
+    JUMP
diff --git a/evm/src/cpu/kernel/interpreter.rs b/evm/src/cpu/kernel/interpreter.rs
index b0d3a784..d856bc2b 100644
--- a/evm/src/cpu/kernel/interpreter.rs
+++ b/evm/src/cpu/kernel/interpreter.rs
@@ -770,7 +770,9 @@ impl<'a> Interpreter<'a> {
     fn run_mload_general(&mut self) {
         let context = self.pop().as_usize();
         let segment = Segment::all()[self.pop().as_usize()];
-        let offset = self.pop().as_usize();
+        let x = self.pop();
+        dbg!(x);
+        let offset = x.as_usize();
         let value = self
             .generation_state
             .memory
diff --git a/evm/src/cpu/kernel/tests/bignum.rs b/evm/src/cpu/kernel/tests/bignum.rs
index eb1726db..ce030b54 100644
--- a/evm/src/cpu/kernel/tests/bignum.rs
+++ b/evm/src/cpu/kernel/tests/bignum.rs
@@ -29,7 +29,7 @@ fn gen_bignum(bit_size: usize) -> BigUint {
 }
 
 fn bignum_len(a: &BigUint) -> usize {
-    a.bits() as usize / BIGNUM_LIMB_BITS + 1
+    ceil_div_usize(a.bits() as usize, BIGNUM_LIMB_BITS)
 }
 
 fn gen_two_bignums_ordered(bit_size: usize) -> (BigUint, BigUint) {