fusee_cpp: implement SDRAM initialization

fusee_cpp/program/source/fusee_uncompress.cpp

@@ -0,0 +1,103 @@
+/*
+ * 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_uncompress.hpp"
+
+namespace ams::nxboot {
+
+    namespace {
+
+        class Lz4Uncompressor {
+            private:
+                const u8 *src;
+                size_t src_size;
+                size_t src_offset;
+                u8 *dst;
+                size_t dst_size;
+                size_t dst_offset;
+            public:
+                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) {
+                    /* ... */
+                }
+
+                void Uncompress() {
+                    while (true) {
+                        /* Read a control byte. */
+                        const u8 control = this->ReadByte();
+
+                        /* Copy what it specifies we should copy. */
+                        this->Copy(this->GetCopySize(control >> 4));
+
+                        /* If we've exceeded size, we're done. */
+                        if (this->src_offset >= this->src_size) {
+                            break;
+                        }
+
+                        /* Read the wide copy offset. */
+                        u16 wide_offset = this->ReadByte();
+                        AMS_ABORT_UNLESS(this->CanRead());
+                        wide_offset |= (this->ReadByte() << 8);
+
+                        /* Determine the copy size. */
+                        const size_t wide_copy_size = this->GetCopySize(control & 0xF);
+
+                        /* Copy bytes. */
+                        const size_t end_offset = this->dst_offset + wide_copy_size + 4;
+                        for (size_t cur_offset = this->dst_offset; cur_offset < end_offset; this->dst_offset = (++cur_offset)) {
+                            AMS_ABORT_UNLESS(wide_offset <= cur_offset);
+
+                            this->dst[cur_offset] = this->dst[cur_offset - wide_offset];
+                        }
+                    }
+                }
+            private:
+                u8 ReadByte() {
+                    return this->src[this->src_offset++];
+                }
+
+                bool CanRead() const {
+                    return this->src_offset < this->src_size;
+                }
+
+                size_t GetCopySize(u8 control) {
+                    size_t size = control;
+
+                    if (control >= 0xF) {
+                        do {
+                            AMS_ABORT_UNLESS(this->CanRead());
+                            control = this->ReadByte();
+                            size += control;
+                        } while (control == 0xFF);
+                    }
+
+                    return size;
+                }
+
+                void Copy(size_t size) {
+                    __builtin_memcpy(this->dst + this->dst_offset, this->src + this->src_offset, size);
+                    this->dst_offset += size;
+                    this->src_offset += size;
+                }
+        };
+
+    }
+
+    void Uncompress(void *dst, size_t dst_size, const void *src, size_t src_size) {
+        /* Create an execute a decompressor. */
+        Lz4Uncompressor(dst, dst_size, src, src_size).Uncompress();
+    }
+
+}