From f117d76b73fb70fdabfaa031e474e5b5814590b3 Mon Sep 17 00:00:00 2001
From: Daniel Lubarov <daniel@lubarov.com>
Date: Sun, 5 Mar 2023 22:30:28 -0800
Subject: [PATCH] sys_gas

---
 evm/src/cpu/kernel/asm/core/syscall_stubs.asm | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/evm/src/cpu/kernel/asm/core/syscall_stubs.asm b/evm/src/cpu/kernel/asm/core/syscall_stubs.asm
index 2ae89586..51c1b01b 100644
--- a/evm/src/cpu/kernel/asm/core/syscall_stubs.asm
+++ b/evm/src/cpu/kernel/asm/core/syscall_stubs.asm
@@ -77,7 +77,15 @@ global sys_msize:
     SWAP1
     EXIT_KERNEL
 global sys_gas:
-    PANIC
+    // stack: kexit_info
+    DUP1 %shr_const(192)
+    // stack: gas_used, kexit_info
+    %mload_context_metadata(@CTX_METADATA_GAS_LIMIT)
+    // stack: gas_limit, gas_used, kexit_info
+    SUB
+    // stack: gas_remaining, kexit_info
+    SWAP1
+    EXIT_KERNEL
 global sys_log0:
     PANIC
 global sys_log1: