From 575337b44978922dc680b197a6881eb3be2214f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <chfast@gmail.com>
Date: Thu, 22 Dec 2016 12:10:31 +0100
Subject: [PATCH] EVM-C: pass callback argument explicitly by pointer

We try to avoid C ABI complex rules like passing structs by value to increase portability.
---
 examples/capi.c | 22 +++++++++++-----------
 include/evm.h   | 10 +++++-----
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/examples/capi.c b/examples/capi.c
index 0afdd43..f87e408 100644
--- a/examples/capi.c
+++ b/examples/capi.c
@@ -16,16 +16,16 @@ struct evm_uint160be address(struct evm_env* env)
     return ret;
 }
 
-union evm_variant query(struct evm_env* env,
-                        enum evm_query_key key,
-                        union evm_variant arg) {
+static union evm_variant query(struct evm_env* env,
+                               enum evm_query_key key,
+                               const union evm_variant* arg) {
     union evm_variant result;
     printf("EVM-C: QUERY %d\n", key);
     switch (key) {
     case EVM_GAS_LIMIT: result.int64 = 314; break;
 
     case EVM_BALANCE:
-        result.uint256be = balance(env, arg.address);
+        result.uint256be = balance(env, arg->address);
         break;
 
     case EVM_ADDRESS:
@@ -37,20 +37,20 @@ union evm_variant query(struct evm_env* env,
     return result;
 }
 
-void update(struct evm_env* env,
-            enum evm_update_key key,
-            union evm_variant arg1,
-            union evm_variant arg2)
+static void update(struct evm_env* env,
+                   enum evm_update_key key,
+                   const union evm_variant* arg1,
+                   const union evm_variant* arg2)
 {
     printf("EVM-C: UPDATE %d\n", key);
 }
 
-int64_t call(
+static int64_t call(
     struct evm_env* _opaqueEnv,
     enum evm_call_kind _kind,
     int64_t _gas,
-    struct evm_uint160be _address,
-    struct evm_uint256be _value,
+    const struct evm_uint160be* _address,
+    const struct evm_uint256be* _value,
     uint8_t const* _inputData,
     size_t _inputSize,
     uint8_t* _outputData,
diff --git a/include/evm.h b/include/evm.h
index 94e123c..b97096f 100644
--- a/include/evm.h
+++ b/include/evm.h
@@ -231,7 +231,7 @@ union evm_variant {
 ///
 typedef union evm_variant (*evm_query_fn)(struct evm_env* env,
                                           enum evm_query_key key,
-                                          union evm_variant arg);
+                                          const union evm_variant* arg);
 
 /// The update callback key.
 enum evm_update_key {
@@ -269,8 +269,8 @@ enum evm_update_key {
 ///   @param arg2 n/a
 typedef void (*evm_update_fn)(struct evm_env* env,
                               enum evm_update_key key,
-                              union evm_variant arg1,
-                              union evm_variant arg2);
+                              const union evm_variant* arg1,
+                              const union evm_variant* arg2);
 
 /// The kind of call-like instruction.
 enum evm_call_kind {
@@ -308,8 +308,8 @@ typedef int64_t (*evm_call_fn)(
     struct evm_env* env,
     enum evm_call_kind kind,
     int64_t gas,
-    struct evm_uint160be address,
-    struct evm_uint256be value,
+    const struct evm_uint160be* address,
+    const struct evm_uint256be* value,
     uint8_t const* input,
     size_t input_size,
     uint8_t* output,