hle_ipc: Add ReadBufferSpan function

Returns a std::span to the buffer address, rather than create a copy of the memory into a std::vector

src/core/hle/kernel/hle_ipc.cpp

@@ -345,6 +345,25 @@ std::vector<u8> HLERequestContext::ReadBuffer(std::size_t buffer_index) const {
     }
 }
 
+std::span<const u8> HLERequestContext::ReadBufferSpan(std::size_t buffer_index) const {
+    LOG_CRITICAL(Debug, "called");
+    const bool is_buffer_a{BufferDescriptorA().size() > buffer_index &&
+                           BufferDescriptorA()[buffer_index].Size()};
+    if (is_buffer_a) {
+        ASSERT_OR_EXECUTE_MSG(
+            BufferDescriptorA().size() > buffer_index, { return {}; },
+            "BufferDescriptorA invalid buffer_index {}", buffer_index);
+        const u8* const mem_ptr = memory.GetPointer(BufferDescriptorA()[buffer_index].Address());
+        return std::span<const u8>(mem_ptr, BufferDescriptorA()[buffer_index].Size());
+    } else {
+        ASSERT_OR_EXECUTE_MSG(
+            BufferDescriptorX().size() > buffer_index, { return {}; },
+            "BufferDescriptorX invalid buffer_index {}", buffer_index);
+        const u8* const mem_ptr = memory.GetPointer(BufferDescriptorX()[buffer_index].Address());
+        return std::span<const u8>(mem_ptr, BufferDescriptorX()[buffer_index].Size());
+    }
+}
+
 std::size_t HLERequestContext::WriteBuffer(const void* buffer, std::size_t size,
                                            std::size_t buffer_index) const {
     if (size == 0) {

src/core/hle/kernel/hle_ipc.h

@@ -7,6 +7,7 @@
 #include <functional>
 #include <memory>
 #include <optional>
+#include <span>
 #include <string>
 #include <type_traits>
 #include <vector>
@@ -273,6 +274,8 @@ public:
     /// Helper function to read a buffer using the appropriate buffer descriptor
     [[nodiscard]] std::vector<u8> ReadBuffer(std::size_t buffer_index = 0) const;
 
+    [[nodiscard]] std::span<const u8> ReadBufferSpan(std::size_t buffer_index = 0) const;
+
     /// Helper function to write a buffer using the appropriate buffer descriptor
     std::size_t WriteBuffer(const void* buffer, std::size_t size,
                             std::size_t buffer_index = 0) const;