code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/loader/3dsx.cpp

@@ -149,7 +149,7 @@ static THREEDSX_Error Load3DSXFile(FileUtil::IOFile& file, u32 base_addr,
         return ERROR_READ;
 
     // BSS clear
-    memset((char*)loadinfo.seg_ptrs[2] + hdr.data_seg_size - hdr.bss_size, 0, hdr.bss_size);
+    std::memset((char*)loadinfo.seg_ptrs[2] + hdr.data_seg_size - hdr.bss_size, 0, hdr.bss_size);
 
     // Relocate the segments
     for (unsigned int current_segment = 0; current_segment < NUM_SEGMENTS; ++current_segment) {

src/core/loader/elf.cpp

@@ -327,7 +327,7 @@ std::shared_ptr<CodeSet> ElfReader::LoadInto(u32 vaddr) {
             codeset_segment->addr = segment_addr;
             codeset_segment->size = aligned_size;
 
-            memcpy(&program_image[current_image_position], GetSegmentPtr(i), p->p_filesz);
+            std::memcpy(&program_image[current_image_position], GetSegmentPtr(i), p->p_filesz);
             current_image_position += aligned_size;
         }
     }

src/core/loader/ncch.cpp

@@ -171,7 +171,7 @@ void AppLoader_NCCH::ParseRegionLockoutInfo(u64 program_id) {
     std::vector<u8> smdh_buffer;
     if (ReadIcon(smdh_buffer) == ResultStatus::Success && smdh_buffer.size() >= sizeof(SMDH)) {
         SMDH smdh;
-        memcpy(&smdh, smdh_buffer.data(), sizeof(SMDH));
+        std::memcpy(&smdh, smdh_buffer.data(), sizeof(SMDH));
         u32 region_lockout = smdh.region_lockout;
         constexpr u32 REGION_COUNT = 7;
         std::vector<u32> regions;
@@ -185,15 +185,20 @@ void AppLoader_NCCH::ParseRegionLockoutInfo(u64 program_id) {
     } else {
         const auto region = Core::GetSystemTitleRegion(program_id);
         if (region.has_value()) {
-            cfg->SetPreferredRegionCodes({region.value()});
+            const std::array regions{region.value()};
+            cfg->SetPreferredRegionCodes(regions);
         }
     }
 }
 
-bool AppLoader_NCCH::IsGbaVirtualConsole(const std::vector<u8>& code) {
-    const u32* gbaVcHeader = reinterpret_cast<const u32*>(code.data() + code.size() - 0x10);
-    return code.size() >= 0x10 && gbaVcHeader[0] == MakeMagic('.', 'C', 'A', 'A') &&
-           gbaVcHeader[1] == 1;
+bool AppLoader_NCCH::IsGbaVirtualConsole(std::span<const u8> code) {
+    if (code.size() < 0x10) [[unlikely]] {
+        return false;
+    }
+
+    u32 gbaVcHeader[2];
+    std::memcpy(gbaVcHeader, code.data() + code.size() - 0x10, sizeof(gbaVcHeader));
+    return gbaVcHeader[0] == MakeMagic('.', 'C', 'A', 'A') && gbaVcHeader[1] == 1;
 }
 
 ResultStatus AppLoader_NCCH::Load(std::shared_ptr<Kernel::Process>& process) {
@@ -317,7 +322,7 @@ ResultStatus AppLoader_NCCH::ReadTitle(std::string& title) {
         return ResultStatus::ErrorInvalidFormat;
     }
 
-    memcpy(&smdh, data.data(), sizeof(Loader::SMDH));
+    std::memcpy(&smdh, data.data(), sizeof(Loader::SMDH));
 
     const auto& short_title = smdh.GetShortTitle(SMDH::TitleLanguage::English);
     auto title_end = std::find(short_title.begin(), short_title.end(), u'\0');

src/core/loader/ncch.h

@@ -78,7 +78,7 @@ private:
     void ParseRegionLockoutInfo(u64 program_id);
 
     /// Detects whether the NCCH contains GBA Virtual Console.
-    bool IsGbaVirtualConsole(const std::vector<u8>& code);
+    bool IsGbaVirtualConsole(std::span<const u8> code);
 
     FileSys::NCCHContainer base_ncch;
     FileSys::NCCHContainer update_ncch;

src/core/loader/smdh.cpp

@@ -11,12 +11,13 @@
 
 namespace Loader {
 
-bool IsValidSMDH(const std::vector<u8>& smdh_data) {
-    if (smdh_data.size() < sizeof(Loader::SMDH))
+bool IsValidSMDH(std::span<const u8> smdh_data) {
+    if (smdh_data.size() < sizeof(Loader::SMDH)) {
         return false;
+    }
 
     u32 magic;
-    memcpy(&magic, smdh_data.data(), sizeof(u32));
+    std::memcpy(&magic, smdh_data.data(), sizeof(u32));
 
     return Loader::MakeMagic('S', 'M', 'D', 'H') == magic;
 }

src/core/loader/smdh.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <array>
+#include <span>
 #include <vector>
 #include "common/common_funcs.h"
 #include "common/common_types.h"
@@ -17,7 +18,7 @@ namespace Loader {
  * @param smdh_data data buffer to test
  * @return bool test result
  */
-bool IsValidSMDH(const std::vector<u8>& smdh_data);
+bool IsValidSMDH(std::span<const u8> smdh_data);
 
 /// SMDH data structure that contains titles, icons etc. See https://www.3dbrew.org/wiki/SMDH
 struct SMDH {