From 3e9b79e088223459891ed07a747c411a6a8921d3 Mon Sep 17 00:00:00 2001 From: Lioncash Date: Thu, 19 Jul 2018 10:15:00 -0400 Subject: [PATCH] fsp_srv: Remove unnecessary std::vector construction in IDirectory's Read() function We were using a second std::vector as a buffer to convert another std::vector's data into a byte sequence, however we can just use pointers to the original data and use them directly with WriteBuffer, which avoids copying the data at all into a separate std::vector. We simply cast the pointers to u8* (which is allowed by the standard, given std::uint8_t is an alias for unsigned char on platforms that we support). --- src/core/hle/service/filesystem/fsp_srv.cpp | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/src/core/hle/service/filesystem/fsp_srv.cpp b/src/core/hle/service/filesystem/fsp_srv.cpp index 4cb2d6909b..673eaabf0d 100644 --- a/src/core/hle/service/filesystem/fsp_srv.cpp +++ b/src/core/hle/service/filesystem/fsp_srv.cpp @@ -4,6 +4,7 @@ #include #include +#include #include #include #include @@ -229,23 +230,20 @@ private: LOG_DEBUG(Service_FS, "called, unk=0x{:X}", unk); // Calculate how many entries we can fit in the output buffer - u64 count_entries = ctx.GetWriteBufferSize() / sizeof(FileSys::Entry); + const u64 count_entries = ctx.GetWriteBufferSize() / sizeof(FileSys::Entry); // Cap at total number of entries. - u64 actual_entries = std::min(count_entries, entries.size() - next_entry_index); + const u64 actual_entries = std::min(count_entries, entries.size() - next_entry_index); - // Read the data from the Directory backend - std::vector entry_data(entries.begin() + next_entry_index, - entries.begin() + next_entry_index + actual_entries); + // Determine data start and end + const auto* begin = reinterpret_cast(entries.data() + next_entry_index); + const auto* end = reinterpret_cast(entries.data() + next_entry_index + actual_entries); + const auto range_size = static_cast(std::distance(begin, end)); next_entry_index += actual_entries; - // Convert the data into a byte array - std::vector output(entry_data.size() * sizeof(FileSys::Entry)); - std::memcpy(output.data(), entry_data.data(), output.size()); - // Write the data to memory - ctx.WriteBuffer(output); + ctx.WriteBuffer(begin, range_size); IPC::ResponseBuilder rb{ctx, 4}; rb.Push(RESULT_SUCCESS);