Atmosphere/fusee_cpp/loader_stub/source/fusee_loader_main.cpp
2021-09-06 16:26:50 -07:00

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2.3 KiB
C++

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <exosphere.hpp>
#include "fusee_loader_uncompress.hpp"
#include "program_lz4.h"
namespace ams::nxboot::loader {
namespace {
constexpr uintptr_t ProgramImageBase = 0x40001000;
constexpr uintptr_t ProgramImageEnd = 0x4003D000;
constexpr size_t ProgramImageSizeMax = ProgramImageEnd - ProgramImageBase;
void CopyBackwards(void *dst, const void *src, size_t size) {
/* We want to copy 32-bits at a time from destination to source. */
const size_t words = util::DivideUp(size, sizeof(u32));
/* Convert to 32-bit pointers. */
u32 *dst_32 = static_cast<u32 *>(dst) + words;
const u32 *src_32 = static_cast<const u32 *>(src) + words;
/* Copy data. */
for (size_t i = 0; i < words; ++i) {
*(--dst_32) = *(--src_32);
}
}
}
NORETURN void UncompressAndExecute(const void *program, size_t program_size) {
/* Relocate the compressed binary to a place where we can safely decompress it. */
void *relocated_program = reinterpret_cast<void *>(util::AlignDown(ProgramImageEnd - program_size, sizeof(u32)));
if (relocated_program != program) {
CopyBackwards(relocated_program, program, program_size);
}
/* Uncompress the program image. */
Uncompress(reinterpret_cast<void *>(ProgramImageBase), ProgramImageSizeMax, relocated_program, program_size);
/* Jump to the boot image. */
reinterpret_cast<void (*)()>(ProgramImageBase)();
/* We will never reach this point. */
__builtin_unreachable();
}
}