From b01698775b468a04e4d0a9bdd86035ff00e6decb Mon Sep 17 00:00:00 2001
From: liamwhite <liamwhite@users.noreply.github.com>
Date: Thu, 2 Feb 2023 15:53:28 -0500
Subject: Revert "hle_ipc: Use std::span to avoid heap allocations/copies when
 calling ReadBuffer"

---
 src/core/hle/service/nvflinger/parcel.h | 87 ++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 46 deletions(-)

(limited to 'src/core/hle/service/nvflinger/parcel.h')

diff --git a/src/core/hle/service/nvflinger/parcel.h b/src/core/hle/service/nvflinger/parcel.h
index d1b6201e0..f3fa2587d 100644
--- a/src/core/hle/service/nvflinger/parcel.h
+++ b/src/core/hle/service/nvflinger/parcel.h
@@ -4,7 +4,6 @@
 #pragma once
 
 #include <memory>
-#include <span>
 #include <vector>
 
 #include "common/alignment.h"
@@ -13,17 +12,18 @@
 
 namespace Service::android {
 
-struct ParcelHeader {
-    u32 data_size;
-    u32 data_offset;
-    u32 objects_size;
-    u32 objects_offset;
-};
-static_assert(sizeof(ParcelHeader) == 16, "ParcelHeader has wrong size");
-
-class InputParcel final {
+class Parcel final {
 public:
-    explicit InputParcel(std::span<const u8> in_data) : read_buffer(std::move(in_data)) {
+    static constexpr std::size_t DefaultBufferSize = 0x40;
+
+    Parcel() : buffer(DefaultBufferSize) {}
+
+    template <typename T>
+    explicit Parcel(const T& out_data) : buffer(DefaultBufferSize) {
+        Write(out_data);
+    }
+
+    explicit Parcel(std::vector<u8> in_data) : buffer(std::move(in_data)) {
         DeserializeHeader();
         [[maybe_unused]] const std::u16string token = ReadInterfaceToken();
     }
@@ -31,9 +31,9 @@ public:
     template <typename T>
     void Read(T& val) {
         static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable.");
-        ASSERT(read_index + sizeof(T) <= read_buffer.size());
+        ASSERT(read_index + sizeof(T) <= buffer.size());
 
-        std::memcpy(&val, read_buffer.data() + read_index, sizeof(T));
+        std::memcpy(&val, buffer.data() + read_index, sizeof(T));
         read_index += sizeof(T);
         read_index = Common::AlignUp(read_index, 4);
     }
@@ -62,10 +62,10 @@ public:
     template <typename T>
     T ReadUnaligned() {
         static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable.");
-        ASSERT(read_index + sizeof(T) <= read_buffer.size());
+        ASSERT(read_index + sizeof(T) <= buffer.size());
 
         T val;
-        std::memcpy(&val, read_buffer.data() + read_index, sizeof(T));
+        std::memcpy(&val, buffer.data() + read_index, sizeof(T));
         read_index += sizeof(T);
         return val;
     }
@@ -101,31 +101,6 @@ public:
         return token;
     }
 
-    void DeserializeHeader() {
-        ASSERT(read_buffer.size() > sizeof(ParcelHeader));
-
-        ParcelHeader header{};
-        std::memcpy(&header, read_buffer.data(), sizeof(ParcelHeader));
-
-        read_index = header.data_offset;
-    }
-
-private:
-    std::span<const u8> read_buffer;
-    std::size_t read_index = 0;
-};
-
-class OutputParcel final {
-public:
-    static constexpr std::size_t DefaultBufferSize = 0x40;
-
-    OutputParcel() : buffer(DefaultBufferSize) {}
-
-    template <typename T>
-    explicit OutputParcel(const T& out_data) : buffer(DefaultBufferSize) {
-        Write(out_data);
-    }
-
     template <typename T>
     void Write(const T& val) {
         static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable.");
@@ -158,20 +133,40 @@ public:
         WriteObject(ptr.get());
     }
 
+    void DeserializeHeader() {
+        ASSERT(buffer.size() > sizeof(Header));
+
+        Header header{};
+        std::memcpy(&header, buffer.data(), sizeof(Header));
+
+        read_index = header.data_offset;
+    }
+
     std::vector<u8> Serialize() const {
-        ParcelHeader header{};
-        header.data_size = static_cast<u32>(write_index - sizeof(ParcelHeader));
-        header.data_offset = sizeof(ParcelHeader);
+        ASSERT(read_index == 0);
+
+        Header header{};
+        header.data_size = static_cast<u32>(write_index - sizeof(Header));
+        header.data_offset = sizeof(Header);
         header.objects_size = 4;
-        header.objects_offset = static_cast<u32>(sizeof(ParcelHeader) + header.data_size);
-        std::memcpy(buffer.data(), &header, sizeof(ParcelHeader));
+        header.objects_offset = static_cast<u32>(sizeof(Header) + header.data_size);
+        std::memcpy(buffer.data(), &header, sizeof(Header));
 
         return buffer;
     }
 
 private:
+    struct Header {
+        u32 data_size;
+        u32 data_offset;
+        u32 objects_size;
+        u32 objects_offset;
+    };
+    static_assert(sizeof(Header) == 16, "ParcelHeader has wrong size");
+
     mutable std::vector<u8> buffer;
-    std::size_t write_index = sizeof(ParcelHeader);
+    std::size_t read_index = 0;
+    std::size_t write_index = sizeof(Header);
 };
 
 } // namespace Service::android
-- 
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