refactor(abi): clean up abi writer

axelarnetwork · Jun 3, 2024 · e35f7c6 · e35f7c6
1 parent 84f1380
commit e35f7c6
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Showing 2 changed files with 46 additions and 60 deletions.
diff --git a/move/abi/sources/abi.move b/move/abi/sources/abi.move
@@ -1,3 +1,6 @@
+/// This module implements ABI encoding/decoding methods for interoperability with EVM message format.
+///
+/// ABI Specification: https://docs.soliditylang.org/en/v0.8.26/abi-spec.html
 module abi::abi {
     // -----
     // Types
@@ -54,19 +57,6 @@ module abi::abi {
         bytes
     }
 
-    public fun read_u256_from_slot(self: &AbiReader, pos: u64): u256 {
-        let mut var = 0u256;
-        let mut i = 0;
-
-        while (i < 32) {
-            var = var << 8;
-            var = var | (self.bytes[i + pos] as u256);
-            i = i + 1;
-        };
-
-        var
-    }
-
     public fun read_u256(self: &mut AbiReader): u256 {
         let mut var = 0u256;
         let mut i = 0;
@@ -93,16 +83,16 @@ module abi::abi {
         let offset = self.read_u256() as u64;
         self.pos = self.head + offset;
 
-        let bytes = self.decode_bytes();
+        let var = self.decode_bytes();
 
         // Move position to the next slot
         self.pos = pos + 32;
 
-        bytes
+        var
     }
 
     public fun read_vector_u256(self: &mut AbiReader): vector<u256> {
-        let mut bytes = vector[];
+        let mut var = vector[];
         let pos = self.pos;
 
         // Move position to the start of the dynamic data
@@ -114,18 +104,18 @@ module abi::abi {
         let mut i = 0;
 
         while (i < length) {
-            bytes.push_back(self.read_u256());
+            var.push_back(self.read_u256());
             i = i + 1;
         };
 
         self.pos = pos + 32;
 
-        bytes
+        var
     }
 
     /// Decode ABI-encoded 'bytes[]'
     public fun read_vector_bytes(self: &mut AbiReader): vector<vector<u8>> {
-        let mut bytes = vector[];
+        let mut var = vector[];
 
         let pos = self.pos;
         let head = self.head;
@@ -140,7 +130,7 @@ module abi::abi {
         let mut i = 0;
 
         while (i < length) {
-            bytes.push_back(self.read_bytes());
+            var.push_back(self.read_bytes());
 
             i = i + 1;
         };
@@ -149,13 +139,22 @@ module abi::abi {
         self.pos = pos + 32;
         self.head = head;
 
-        bytes
+        var
     }
 
     public fun write_u256(self: &mut AbiWriter, var: u256): &mut AbiWriter {
         let pos = self.pos;
-        self.encode_u256(pos, var);
-        self.pos = self.pos + 1;
+        let mut i = 0;
+
+        while (i < 32) {
+            let exp = ((31 - i) * 8 as u8);
+            let byte = (var >> exp & 255 as u8);
+            *self.bytes.borrow_mut(i + pos) = byte;
+            i = i + 1;
+        };
+
+        self.pos = pos + 32;
+
         self
     }
 
@@ -164,45 +163,41 @@ module abi::abi {
     }
 
     public fun write_bytes(self: &mut AbiWriter, var: vector<u8>): &mut AbiWriter {
-        let pos = self.pos;
-        let length = self.bytes.length() as u256;
-        self.encode_u256(pos, length);
+        let offset = self.bytes.length() as u256;
+        self.write_u256(offset);
 
+        // Write dynamic data length and bytes at the tail
         self.append_u256(var.length() as u256);
-
         self.append_bytes(var);
-        self.pos = self.pos + 1;
+
         self
     }
 
     public fun write_vector_u256(self: &mut AbiWriter, var: vector<u256>): &mut AbiWriter {
-        let pos = self.pos;
-        let length = self.bytes.length();
-        self.encode_u256(pos, length as u256);
+        let offset = self.bytes.length() as u256;
+        self.write_u256(offset);
 
         let length = var.length();
         self.append_u256(length as u256);
 
-        let mut i = 0u64;
+        let mut i = 0;
         while (i < length) {
             self.append_u256(var[i]);
             i = i + 1;
         };
 
-        self.pos = self.pos + 1;
         self
     }
 
     public fun write_vector_bytes(self: &mut AbiWriter, var: vector<vector<u8>>): &mut AbiWriter {
-        let pos = self.pos;
-        let length = self.bytes.length();
-        self.encode_u256(pos, length as u256);
+        let offset = self.bytes.length() as u256;
+        self.write_u256(offset);
 
         let length = var.length();
         self.append_u256(length as u256);
 
-        let mut i = 0;
         let mut writer = new_writer(length);
+        let mut i = 0;
 
         while (i < length) {
             writer.write_bytes(var[i]);
@@ -211,24 +206,13 @@ module abi::abi {
 
         self.append_bytes(writer.into_bytes());
 
-        self.pos = self.pos + 1;
         self
     }
 
     // ------------------
     // Internal Functions
     // ------------------
 
-    fun encode_u256(self: &mut AbiWriter, pos: u64, var: u256) {
-        let mut i = 0;
-
-        while (i < 32) {
-            let exp = ((31 - i) * 8 as u8);
-            *self.bytes.borrow_mut(i + 32 * pos) = (var >> exp & 255 as u8);
-            i = i + 1;
-        };
-    }
-
     fun append_u256(self: &mut AbiWriter, var: u256) {
         let mut i = 0;
         while (i < 32) {

diff --git a/move/its/sources/service.move b/move/its/sources/service.move
@@ -66,12 +66,13 @@ module its::service {
         let decimals = coin_info.decimals();
         let mut writer = abi::new_writer(6);
 
-        writer.write_u256(MESSAGE_TYPE_DEPLOY_INTERCHAIN_TOKEN);
-        writer.write_u256(token_id.to_u256());
-        writer.write_bytes(*string::bytes(&name));
-        writer.write_bytes(*ascii::as_bytes(&symbol));
-        writer.write_u256((decimals as u256));
-        writer.write_bytes(vector::empty());
+        writer
+            .write_u256(MESSAGE_TYPE_DEPLOY_INTERCHAIN_TOKEN)
+            .write_u256(token_id.to_u256())
+            .write_bytes(*string::bytes(&name))
+            .write_bytes(*ascii::as_bytes(&symbol))
+            .write_u256((decimals as u256))
+            .write_bytes(vector::empty());
 
         send_payload(self, destination_chain, writer.into_bytes());
     }
@@ -89,12 +90,13 @@ module its::service {
         let (_version, data) = its_utils::decode_metadata(metadata);
         let mut writer = abi::new_writer(6);
 
-        writer.write_u256(MESSAGE_TYPE_INTERCHAIN_TRANSFER);
-        writer.write_u256(token_id.to_u256());
-        writer.write_bytes(address::to_bytes(ctx.sender()));
-        writer.write_bytes(destination_address);
-        writer.write_u256(amount);
-        writer.write_bytes(data);
+        writer
+            .write_u256(MESSAGE_TYPE_INTERCHAIN_TRANSFER)
+            .write_u256(token_id.to_u256())
+            .write_bytes(address::to_bytes(ctx.sender()))
+            .write_bytes(destination_address)
+            .write_u256(amount)
+            .write_bytes(data);
 
         self.coin_management_mut(token_id)
             .take_coin(coin);