From 85e2864a7f43731bb0aec96f09f5202278284fd2 Mon Sep 17 00:00:00 2001
From: Pia <76558220+rkdud007@users.noreply.github.com>
Date: Tue, 12 Sep 2023 01:31:30 +0900
Subject: [PATCH] add msize opcode (#286)

---
 .../src/instructions/memory_operations.cairo  |  3 +-
 crates/evm/src/memory.cairo                   |  7 +++
 .../test_memory_operations.cairo              | 49 +++++++++++++++++++
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/crates/evm/src/instructions/memory_operations.cairo b/crates/evm/src/instructions/memory_operations.cairo
index ab8df370a..9074572ab 100644
--- a/crates/evm/src/instructions/memory_operations.cairo
+++ b/crates/evm/src/instructions/memory_operations.cairo
@@ -41,7 +41,8 @@ impl MemoryOperation of MemoryOperationTrait {
     /// Get the value of memory size.
     /// # Specification: https://www.evm.codes/#59?fork=shanghai
     fn exec_msize(ref self: ExecutionContext) -> Result<(), EVMError> {
-        Result::Ok(())
+        let msize: u256 = self.memory.size().into();
+        self.stack.push(msize)
     }
 
     /// 0x56 - JUMP operation
diff --git a/crates/evm/src/memory.cairo b/crates/evm/src/memory.cairo
index 73118a455..5552afa10 100644
--- a/crates/evm/src/memory.cairo
+++ b/crates/evm/src/memory.cairo
@@ -15,6 +15,7 @@ struct Memory {
 
 trait MemoryTrait {
     fn new() -> Memory;
+    fn size(ref self: Memory) -> usize;
     fn store(ref self: Memory, element: u256, offset: usize);
     fn store_n(ref self: Memory, elements: Span<u8>, offset: usize);
     fn ensure_length(ref self: Memory, length: usize) -> usize;
@@ -31,6 +32,12 @@ impl MemoryImpl of MemoryTrait {
         Memory { items: Default::default(), bytes_len: 0, }
     }
 
+    /// Return size of the memory.
+    #[inline(always)]
+    fn size(ref self: Memory) -> usize {
+        self.bytes_len
+    }
+
     /// Stores a 32-bytes element into the memory.
     ///
     /// If the offset is aligned with the 16-bytes words in memory, the element is stored directly.
diff --git a/crates/evm/src/tests/test_instructions/test_memory_operations.cairo b/crates/evm/src/tests/test_instructions/test_memory_operations.cairo
index 0c79ecc9c..6594fc4bc 100644
--- a/crates/evm/src/tests/test_instructions/test_memory_operations.cairo
+++ b/crates/evm/src/tests/test_instructions/test_memory_operations.cairo
@@ -12,6 +12,7 @@ use evm::errors::{EVMError, STACK_UNDERFLOW};
 use evm::context::{
     ExecutionContext, ExecutionContextTrait, BoxDynamicExecutionContextDestruct, CallContextTrait,
 };
+use evm::helpers::U256IntoResultU32;
 use integer::BoundedInt;
 
 
@@ -251,3 +252,51 @@ fn test_exec_mstore8_should_store_last_uint8_offset_63() {
     let (stored, _) = ctx.memory.load(32);
     assert(stored == 0xEF, 'mstore8 failed');
 }
+
+
+#[test]
+#[available_gas(20000000)]
+fn test_msize_initial() {
+    // Given
+    let mut ctx = setup_execution_context();
+
+    // When
+    let result = ctx.exec_msize();
+
+    // Then
+    assert(result.is_ok(), 'should have succeeded');
+    assert(ctx.stack.len() == 1, 'stack should have one element');
+    assert(ctx.stack.pop().unwrap() == 0, 'initial memory size should be 0');
+}
+
+#[test]
+#[available_gas(20000000)]
+fn test_exec_msize_store_max_offset_0() {
+    // Given
+    let mut ctx = setup_execution_context();
+    ctx.memory.store(BoundedInt::<u256>::max(), 0x00);
+
+    // When
+    let result = ctx.exec_msize();
+
+    // Then
+    assert(result.is_ok(), 'should have succeeded');
+    assert(ctx.stack.len() == 1, 'stack should have one element');
+    assert(ctx.stack.pop().unwrap() == 32, 'should 32 bytes after MSTORE');
+}
+
+#[test]
+#[available_gas(20000000)]
+fn test_exec_msize_store_max_offset_1() {
+    // Given
+    let mut ctx = setup_execution_context();
+    ctx.memory.store(BoundedInt::<u256>::max(), 0x01);
+
+    // When
+    let result = ctx.exec_msize();
+
+    // Then
+    assert(result.is_ok(), 'should have succeeded');
+    assert(ctx.stack.len() == 1, 'stack should have one element');
+    assert(ctx.stack.pop().unwrap() == 64, 'should 64 bytes after MSTORE');
+}