From 0d8d4063090abfe5dfda1c911c63c6e3bb114325 Mon Sep 17 00:00:00 2001
From: Mathieu <60658558+enitrat@users.noreply.github.com>
Date: Tue, 3 Sep 2024 15:29:44 +0200
Subject: [PATCH] feat: blobhash opcode (#889)

---
 crates/evm/src/gas.cairo                      |  3 +++
 .../src/instructions/block_information.cairo  | 25 +++++++++++++++++++
 crates/evm/src/interpreter.cairo              |  4 +++
 3 files changed, 32 insertions(+)

diff --git a/crates/evm/src/gas.cairo b/crates/evm/src/gas.cairo
index 7d7c63e80..0b4f630cd 100644
--- a/crates/evm/src/gas.cairo
+++ b/crates/evm/src/gas.cairo
@@ -52,6 +52,9 @@ const INITCODE_WORD_COST: u128 = 2;
 
 const CALL_STIPEND: u128 = 2300;
 
+// EIP-4844
+pub const BLOB_HASH_COST: u128 = 3;
+
 /// Defines the gas cost and stipend for executing call opcodes.
 ///
 /// # Struct fields
diff --git a/crates/evm/src/instructions/block_information.cairo b/crates/evm/src/instructions/block_information.cairo
index 84eeb1573..c163de3fa 100644
--- a/crates/evm/src/instructions/block_information.cairo
+++ b/crates/evm/src/instructions/block_information.cairo
@@ -126,6 +126,16 @@ impl BlockInformation of BlockInformationTrait {
         self.stack.push(self.env.gas_price.into())
     }
 
+    /// 0x49 - BLOBHASH
+    /// Returns the value of the blob hash of the current block
+    /// Always returns Zero in the context of Kakarot
+    /// # Specification: https://www.evm.codes/#49?fork=cancun
+    fn exec_blobhash(ref self: VM) -> Result<(), EVMError> {
+        self.charge_gas(gas::BLOB_HASH_COST)?;
+
+        self.stack.push(0)
+    }
+
     /// 0x4A - BLOBBASEFEE
     /// Returns the value of the blob base-fee of the current block
     /// Always returns Zero in the context of Kakarot
@@ -333,6 +343,20 @@ mod tests {
         assert(result == 0x00, 'stack top should be zero');
     }
 
+    #[test]
+    fn test_blobhash_should_return_zero() {
+        // Given
+        let mut vm = VMBuilderTrait::new_with_presets().build();
+
+        // When
+        vm.exec_blobhash().unwrap();
+
+        // Then
+        assert_eq!(vm.stack.len(), 1);
+        assert_eq!(vm.stack.peek().unwrap(), 0);
+    }
+
+
     #[test]
     fn test_blobbasefee_should_return_zero() {
         // Given
@@ -346,6 +370,7 @@ mod tests {
         assert(vm.stack.peek().unwrap() == 0, 'stack top should be 0');
     }
 
+
     // *************************************************************************
     // 0x41: COINBASE
     // *************************************************************************
diff --git a/crates/evm/src/interpreter.cairo b/crates/evm/src/interpreter.cairo
index 42222db5f..f0dc036cc 100644
--- a/crates/evm/src/interpreter.cairo
+++ b/crates/evm/src/interpreter.cairo
@@ -444,6 +444,10 @@ impl EVMImpl of EVMTrait {
             // BASEFEE
             return self.exec_basefee();
         }
+        if opcode == 73 {
+            // BLOBHASH
+            return self.exec_blobhash();
+        }
         if opcode == 74 {
             // BLOBBASEFEE
             return self.exec_blobbasefee();