From f2d0daf60deac64f32b4d74adf26421b52a8f71d Mon Sep 17 00:00:00 2001
From: mokurin000 <1348292515a@gmail.com>
Date: Thu, 31 Jul 2025 12:36:59 +0800
Subject: [PATCH] perf: add back zero-copy decode for mai 1.50

---
 sdgb-api/src/title/encryption/mod.rs | 25 ++++++-------------------
 sdgb-api/src/title/mod.rs            |  2 +-
 2 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/sdgb-api/src/title/encryption/mod.rs b/sdgb-api/src/title/encryption/mod.rs
index 4ea02d7..fc33094 100644
--- a/sdgb-api/src/title/encryption/mod.rs
+++ b/sdgb-api/src/title/encryption/mod.rs
@@ -12,8 +12,8 @@ use crate::error::ApiError;
 use crate::title::{MaiVersion, MaiVersionExt, Sdgb1_40, Sdgb1_50};
 
 impl MaiVersionExt for Sdgb1_40 {
-    fn decode(data: impl AsRef<[u8]>) -> Result<Vec<u8>, ApiError> {
-        let mut decompressed = decompress(data.as_ref());
+    fn decode(mut data: impl AsMut<[u8]>) -> Result<Vec<u8>, ApiError> {
+        let mut decompressed = decompress(data.as_mut());
         if decompressed.is_empty() {
             return Err(ApiError::EmptyResponse);
         }
@@ -41,19 +41,13 @@ impl MaiVersionExt for Sdgb1_40 {
 }
 
 impl MaiVersionExt for Sdgb1_50 {
-    fn decode(data: impl AsRef<[u8]>) -> Result<Vec<u8>, ApiError> {
-        let mut data = data.as_ref().to_vec();
-        if data.is_empty() {
+    fn decode(mut data: impl AsMut<[u8]>) -> Result<Vec<u8>, ApiError> {
+        if data.as_mut().is_empty() {
             return Err(ApiError::EmptyResponse);
         }
 
-        if data.len() % 16 != 0 {
-            let pad = 16 - (data.len() % 16);
-            data.resize(data.len() + pad, pad as _);
-        }
-
-        debug!("data size: {}", data.len());
-        let decrypted = decrypt_vec(&data, Self::AES_KEY, Self::AES_IV)?;
+        debug!("data size: {}", data.as_mut().len());
+        let decrypted = decrypt(&mut data, Self::AES_KEY, Self::AES_IV)?;
         Ok(decompress(decrypted))
     }
 
@@ -111,13 +105,6 @@ fn decrypt<'ct>(
     Ok(result)
 }
 
-fn decrypt_vec(data: impl AsRef<[u8]>, key: &[u8; 32], iv: &[u8; 16]) -> Result<Vec<u8>, ApiError> {
-    let key = GenericArray::from_slice(key);
-    let iv = GenericArray::from_slice(iv);
-    let decryptor = Aes256CbcDec::new(key, iv);
-    Ok(decryptor.decrypt_padded_vec_mut::<Pkcs7>(data.as_ref())?)
-}
-
 #[cfg(test)]
 mod _tests {
 
diff --git a/sdgb-api/src/title/mod.rs b/sdgb-api/src/title/mod.rs
index eb5a66f..619eda0 100644
--- a/sdgb-api/src/title/mod.rs
+++ b/sdgb-api/src/title/mod.rs
@@ -25,7 +25,7 @@ pub trait MaiVersion {
 
 pub trait MaiVersionExt: MaiVersion {
     fn encode(data: impl AsRef<[u8]>) -> Result<Vec<u8>, ApiError>;
-    fn decode(data: impl AsRef<[u8]>) -> Result<Vec<u8>, ApiError>;
+    fn decode(data: impl AsMut<[u8]>) -> Result<Vec<u8>, ApiError>;
 
     fn api_hash(api: APIMethod) -> String {
         let api_name: &str = api.into();