mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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103 lines
3.8 KiB
C++
103 lines
3.8 KiB
C++
/*
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* Copyright (c) 2018-2020 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <exosphere.hpp>
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#include "secmon_loader_uncompress.hpp"
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namespace ams::secmon::loader {
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namespace {
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class Lz4Uncompressor {
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private:
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const u8 *src;
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size_t src_size;
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size_t src_offset;
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u8 *dst;
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size_t dst_size;
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size_t dst_offset;
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public:
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Lz4Uncompressor(void *dst, size_t dst_size, const void *src, size_t src_size) : src(static_cast<const u8 *>(src)), src_size(src_size), src_offset(0), dst(static_cast<u8 *>(dst)), dst_size(dst_size), dst_offset(0) {
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/* ... */
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}
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void Uncompress() {
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while (true) {
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/* Read a control byte. */
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const u8 control = this->ReadByte();
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/* Copy what it specifies we should copy. */
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this->Copy(this->GetCopySize(control >> 4));
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/* If we've exceeded size, we're done. */
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if (this->src_offset >= this->src_size) {
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break;
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}
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/* Read the wide copy offset. */
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u16 wide_offset = this->ReadByte();
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AMS_ABORT_UNLESS(this->CanRead());
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wide_offset |= (this->ReadByte() << 8);
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/* Determine the copy size. */
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const size_t wide_copy_size = this->GetCopySize(control & 0xF);
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/* Copy bytes. */
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const size_t end_offset = this->dst_offset + wide_copy_size + 4;
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for (size_t cur_offset = this->dst_offset; cur_offset < end_offset; this->dst_offset = (++cur_offset)) {
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AMS_ABORT_UNLESS(wide_offset <= cur_offset);
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this->dst[cur_offset] = this->dst[cur_offset - wide_offset];
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}
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}
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}
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private:
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u8 ReadByte() {
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return this->src[this->src_offset++];
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}
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bool CanRead() const {
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return this->src_offset < this->src_size;
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}
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size_t GetCopySize(u8 control) {
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size_t size = control;
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if (control >= 0xF) {
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do {
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AMS_ABORT_UNLESS(this->CanRead());
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control = this->ReadByte();
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size += control;
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} while (control == 0xFF);
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}
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return size;
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}
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void Copy(size_t size) {
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__builtin_memcpy(this->dst + this->dst_offset, this->src + this->src_offset, size);
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this->dst_offset += size;
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this->src_offset += size;
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}
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};
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}
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void Uncompress(void *dst, size_t dst_size, const void *src, size_t src_size) {
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/* Create an execute a decompressor. */
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Lz4Uncompressor(dst, dst_size, src, src_size).Uncompress();
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}
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} |