fusee-cpp: add basic structural stubs

fusee_cpp/loader_stub/Makefile

@@ -0,0 +1,154 @@
+#---------------------------------------------------------------------------------
+# Define the atmosphere board and cpu
+#---------------------------------------------------------------------------------
+export ATMOSPHERE_BOARD := nx-hac-001
+export ATMOSPHERE_CPU   := arm7tdmi
+
+#---------------------------------------------------------------------------------
+# pull in common atmosphere configuration
+#---------------------------------------------------------------------------------
+THIS_MAKEFILE     := $(abspath $(lastword $(MAKEFILE_LIST)))
+CURRENT_DIRECTORY := $(abspath $(dir $(THIS_MAKEFILE)))
+include  $(dir $(abspath $(lastword $(MAKEFILE_LIST))))/../../libraries/config/templates/exosphere.mk
+
+#---------------------------------------------------------------------------------
+# no real need to edit anything past this point unless you need to add additional
+# rules for different file extensions
+#---------------------------------------------------------------------------------
+ifneq ($(__RECURSIVE__),1)
+#---------------------------------------------------------------------------------
+
+export VPATH	:=	$(foreach dir,$(SOURCES),$(CURDIR)/$(dir)) $(CURDIR)/include \
+			$(foreach dir,$(DATA),$(CURDIR)/$(dir))
+
+CFILES      :=	$(call FIND_SOURCE_FILES,$(SOURCES),c)
+CPPFILES    :=	$(call FIND_SOURCE_FILES,$(SOURCES),cpp)
+SFILES      :=	$(call FIND_SOURCE_FILES,$(SOURCES),s)
+BINFILES    :=
+
+#---------------------------------------------------------------------------------
+# use CXX for linking C++ projects, CC for standard C
+#---------------------------------------------------------------------------------
+ifeq ($(strip $(CPPFILES)),)
+#---------------------------------------------------------------------------------
+	export LD	:=	$(CC)
+#---------------------------------------------------------------------------------
+else
+#---------------------------------------------------------------------------------
+	export LD	:=	$(CXX)
+#---------------------------------------------------------------------------------
+endif
+#---------------------------------------------------------------------------------
+
+export OFILES_BIN	:=	$(addsuffix .o,$(BINFILES))
+export OFILES_SRC	:=	$(CPPFILES:.cpp=.o) $(CFILES:.c=.o) $(SFILES:.s=.o)
+export OFILES 	:=	$(OFILES_BIN) $(OFILES_SRC) program.lz4.o
+export HFILES_BIN	:=	$(addsuffix .h,$(subst .,_,$(subst -,_,$(BINFILES))))
+
+export INCLUDE	:=	$(foreach dir,$(INCLUDES),-I$(CURDIR)/$(dir)) \
+			$(foreach dir,$(LIBDIRS),-I$(dir)/include) \
+			-I.
+
+export LIBPATHS	:=	$(foreach dir,$(LIBDIRS),-L$(dir)/$(ATMOSPHERE_LIBRARY_DIR))
+
+export TOPDIR := $(CURRENT_DIRECTORY)
+
+OUTPUT_BASE := $(TOPDIR)/$(notdir $(TOPDIR))
+
+#---------------------------------------------------------------------------------
+
+ATMOSPHERE_BUILD_CONFIGS :=
+all: release
+
+define ATMOSPHERE_ADD_TARGET
+
+ATMOSPHERE_BUILD_CONFIGS += $(strip $1)
+
+$(strip $1): check_libexo_$(strip $1) $$(ATMOSPHERE_BUILD_DIR)/$(strip $1)
+	@$$(MAKE) __RECURSIVE__=1 OUTPUT=$$(OUTPUT_BASE)$(strip $2) $(3) \
+	ATMOSPHERE_BUILD_TARGET_IDENTIFIER=$(strip $1) \
+	ATMOSPHERE_BUILD_TARGET_BINARY_SUFFIX=$(strip $2) \
+	DEPSDIR=$$(CURDIR)/$$(ATMOSPHERE_BUILD_DIR)/$(strip $1) \
+	LIBEXOSPHERE_NAME=exosphere$(strip $2) \
+	--no-print-directory -C $$(ATMOSPHERE_BUILD_DIR)/$(strip $1) \
+	-f $$(THIS_MAKEFILE)
+
+check_libexo_$(strip $1):
+	@$$(MAKE) --no-print-directory -C $$(ATMOSPHERE_LIBRARIES_DIR)/libexosphere $$(ATMOSPHERE_ARCH_NAME)-$(strip $1)
+
+clean-$(strip $1):
+	@echo clean $(strip $1) ...
+	@rm -fr $$(ATMOSPHERE_BUILD_DIR)/$(strip $1) $$(OUTPUT_BASE)$(strip $2).bin $$(OUTPUT_BASE)$(strip $2).elf
+
+endef
+
+$(eval $(call ATMOSPHERE_ADD_TARGET, release,     , \
+	ATMOSPHERE_BUILD_SETTINGS="-DAMS_FORCE_DISABLE_DETAILED_ASSERTIONS" \
+))
+
+$(eval $(call ATMOSPHERE_ADD_TARGET, debug, _debug, \
+	ATMOSPHERE_BUILD_SETTINGS="-DAMS_FORCE_DISABLE_DETAILED_ASSERTIONS -DAMS_BUILD_FOR_DEBUGGING" \
+))
+
+$(eval $(call ATMOSPHERE_ADD_TARGET, audit, _audit, \
+	ATMOSPHERE_BUILD_SETTINGS="-DAMS_FORCE_DISABLE_DETAILED_ASSERTIONS -DAMS_BUILD_FOR_AUDITING" \
+))
+
+$(ATMOSPHERE_BUILD_DIR)/%:
+	@[ -d $@ ] || mkdir -p $@
+
+#---------------------------------------------------------------------------------
+clean: $(foreach config,$(ATMOSPHERE_BUILD_CONFIGS),clean-$(config))
+
+.PHONY: all clean $(foreach config,$(ATMOSPHERE_BUILD_CONFIGS),$(config) clean-$(config))
+
+#---------------------------------------------------------------------------------
+else
+
+DEPENDS	:=	$(OFILES:.o=.d)
+
+#---------------------------------------------------------------------------------
+# main targets
+#---------------------------------------------------------------------------------
+
+$(OUTPUT).bin	:	$(OUTPUT).elf
+	$(OBJCOPY) -S -O binary --set-section-flags .bss=alloc,load,contents $< $@
+	@echo built ... $(notdir $@)
+
+$(OUTPUT).elf	:	$(OFILES)
+
+$(OFILES)	:	$(ATMOSPHERE_LIBRARIES_DIR)/libexosphere/$(ATMOSPHERE_LIBRARY_DIR)/lib$(LIBEXOSPHERE_NAME).a
+
+program.lz4.o: program_lz4.h
+
+program_lz4.h:	$(TOPDIR)/../program/program$(ATMOSPHERE_BUILD_TARGET_BINARY_SUFFIX).lz4
+	@echo $(notdir $<)
+	@rm -rf tmp_program_$(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)
+	@mkdir -p tmp_program_$(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)
+	@cp $(TOPDIR)/../program/program$(ATMOSPHERE_BUILD_TARGET_BINARY_SUFFIX).lz4 tmp_program_$(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)/program.lz4
+	@bin2s -a 8 -H program_lz4.h tmp_program_$(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)/program.lz4 | $(AS) -o program.lz4.o
+	@rm -rf tmp_program_$(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)
+
+$(TOPDIR)/../program/program$(ATMOSPHERE_BUILD_TARGET_BINARY_SUFFIX).lz4:
+	@$(MAKE) __RECURSIVE__=0 --no-print-directory -C $(TOPDIR)/../program $(ATMOSPHERE_BUILD_TARGET_IDENTIFIER)
+
+%.elf:
+	@echo linking $(notdir $@)
+	$(LD) $(LDFLAGS) $(OFILES) $(LIBPATHS) $(LIBS) -o $@
+	@$(NM) -CSn $@ > $(notdir $*.lst)
+
+$(OFILES_SRC)	: $(HFILES_BIN) program_lz4.h
+
+#---------------------------------------------------------------------------------
+# you need a rule like this for each extension you use as binary data
+#---------------------------------------------------------------------------------
+%.bin.o	%_bin.h:	%.bin
+#---------------------------------------------------------------------------------
+	@echo $(notdir $<)
+	@$(bin2o)
+
+-include $(DEPENDS)
+
+#---------------------------------------------------------------------------------------
+endif
+#---------------------------------------------------------------------------------------

fusee_cpp/loader_stub/loader_stub.ld

@@ -0,0 +1,125 @@
+OUTPUT_ARCH(arm)
+ENTRY(_ZN3ams6nxboot6loader5StartEv)
+
+MEMORY
+{
+    NULL        : ORIGIN = 0,          LENGTH = 4K
+    data        : ORIGIN = 0x40010000, LENGTH = 0x28000
+    loader_stub : ORIGIN = 0x4003D000, LENGTH = 4K
+}
+
+
+SECTIONS
+{
+	/* =========== CODE section =========== */
+
+	. = ORIGIN(data);
+	__data_start__ = . ;
+
+    .crt0 :
+    {
+        KEEP(*(.crt0 .crt0.*))
+        . = ALIGN(8);
+    } >data
+
+	/* =========== RODATA section =========== */
+	. = ALIGN(8);
+
+	.rodata :
+	{
+		*(.rodata .rodata.* .gnu.linkonce.r.*)
+		. = ALIGN(8);
+	} >data
+
+	.eh_frame_hdr     : { __eh_frame_hdr_start = .; *(.eh_frame_hdr) *(.eh_frame_entry .eh_frame_entry.*) __eh_frame_hdr_end = .; } >data
+	.eh_frame         : ONLY_IF_RO { KEEP (*(.eh_frame)) *(.eh_frame.*) } >data
+	.gcc_except_table : ONLY_IF_RO { *(.gcc_except_table .gcc_except_table.*) } >data
+	.gnu_extab        : ONLY_IF_RO { *(.gnu_extab*) } >data
+
+	.hash              : { *(.hash) } >data
+
+	/* =========== DATA section =========== */
+	. = ALIGN(8);
+
+	.eh_frame : ONLY_IF_RW { KEEP (*(.eh_frame)) *(.eh_frame.*) } >data
+	.gcc_except_table : ONLY_IF_RW { *(.gcc_except_table .gcc_except_table.*) } >data
+	.gnu_extab : ONLY_IF_RW { *(.gnu_extab*) } >data
+	.exception_ranges : ONLY_IF_RW { *(.exception_ranges .exception_ranges*) } >data
+
+	.data ALIGN(8) :
+	{
+		*(.data .data.* .gnu.linkonce.d.*)
+		SORT(CONSTRUCTORS)
+	} >data
+
+	__bss_start__ = .;
+	.bss (NOLOAD) :
+	{
+		*(.dynbss)
+		*(.bss .bss.* .gnu.linkonce.b.*)
+		*(COMMON)
+		. = ALIGN(16);
+	} >data :NONE
+	__bss_end__ = .;
+
+	__data_end__ = ABSOLUTE(.);
+
+
+	.loader_stub :
+	{
+        . = ALIGN(32);
+        PROVIDE (__loader_stub_start__  = ABSOLUTE(.));
+        PROVIDE (__loader_stub_lma__    = LOADADDR(.loader_stub));
+        fusee_loader_main.o(.text*)
+        fusee_loader_uncompress.o(.text*)
+        fusee_loader_error.o(.text*)
+        fusee_loader_main.o(.rodata*)
+        fusee_loader_uncompress.o(.rodata*)
+        fusee_loader_error.o(.rodata*)
+        fusee_loader_main.o(.data*)
+        fusee_loader_uncompress.o(.data*)
+        fusee_loader_error.o(.data*)
+        . = ALIGN(32);
+        PROVIDE (__loader_stub_end__ = ABSOLUTE(.));
+	} >loader_stub AT>data
+
+	/* ==================
+	   ==== Metadata ====
+	   ================== */
+
+	/* Discard sections that difficult post-processing */
+	/DISCARD/ : { *(.group .comment .note .interp) }
+
+	/* Stabs debugging sections. */
+	.stab          0 : { *(.stab) }
+	.stabstr       0 : { *(.stabstr) }
+	.stab.excl     0 : { *(.stab.excl) }
+	.stab.exclstr  0 : { *(.stab.exclstr) }
+	.stab.index    0 : { *(.stab.index) }
+	.stab.indexstr 0 : { *(.stab.indexstr) }
+
+	/* DWARF debug sections.
+	   Symbols in the DWARF debugging sections are relative to the beginning
+	   of the section so we begin them at 0. */
+
+	/* DWARF 1 */
+	.debug          0 : { *(.debug) }
+	.line           0 : { *(.line) }
+
+	/* GNU DWARF 1 extensions */
+	.debug_srcinfo  0 : { *(.debug_srcinfo) }
+	.debug_sfnames  0 : { *(.debug_sfnames) }
+
+	/* DWARF 1.1 and DWARF 2 */
+	.debug_aranges  0 : { *(.debug_aranges) }
+	.debug_pubnames 0 : { *(.debug_pubnames) }
+
+	/* DWARF 2 */
+	.debug_info     0 : { *(.debug_info) }
+	.debug_abbrev   0 : { *(.debug_abbrev) }
+	.debug_line     0 : { *(.debug_line) }
+	.debug_frame    0 : { *(.debug_frame) }
+	.debug_str      0 : { *(.debug_str) }
+	.debug_loc      0 : { *(.debug_loc) }
+	.debug_macinfo  0 : { *(.debug_macinfo) }
+}

fusee_cpp/loader_stub/loader_stub.specs

@@ -0,0 +1,4 @@
+%rename link old_link
+
+*link:
+%(old_link) -T %:getenv(TOPDIR /loader_stub.ld) --gc-sections --nmagic

fusee_cpp/loader_stub/source/fusee_loader_error.cpp

@@ -0,0 +1,47 @@
+/*
+ * 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_error.hpp"
+
+namespace ams::diag {
+
+    NORETURN void AbortImpl(const char *file, int line, const char *func, const char *expr, u64 value, const char *format, ...) {
+        AMS_UNUSED(file, line, func, expr, value, format);
+        ams::nxboot::loader::ErrorStop();
+    }
+
+    NORETURN void AbortImpl(const char *file, int line, const char *func, const char *expr, u64 value) {
+        AMS_UNUSED(file, line, func, expr, value);
+        ams::nxboot::loader::ErrorStop();
+    }
+
+    NORETURN void AbortImpl() {
+        ams::nxboot::loader::ErrorStop();
+    }
+
+}
+
+namespace ams::nxboot::loader {
+
+    NORETURN void ErrorStop() {
+        /* Halt ourselves. */
+        while (true) {
+            reg::Write(secmon::MemoryRegionPhysicalDeviceFlowController.GetAddress() + FLOW_CTLR_HALT_COP_EVENTS, FLOW_REG_BITS_ENUM(HALT_COP_EVENTS_MODE, FLOW_MODE_STOP),
+                                                                                                                  FLOW_REG_BITS_ENUM(HALT_COP_EVENTS_JTAG,        ENABLED));
+        }
+    }
+
+}

fusee_cpp/loader_stub/source/fusee_loader_error.hpp

@@ -0,0 +1,23 @@
+/*
+ * 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>
+#pragma once
+
+namespace ams::nxboot::loader {
+
+    NORETURN void ErrorStop();
+
+}

fusee_cpp/loader_stub/source/fusee_loader_main.cpp

@@ -0,0 +1,61 @@
+/*
+ * 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();
+    }
+
+}

fusee_cpp/loader_stub/source/fusee_loader_start.s

@@ -0,0 +1,59 @@
+/*
+ * 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/>.
+ */
+
+
+
+.section .crt0._ZN3ams6nxboot6loader5StartEv, "ax", %progbits
+.arm
+.align 5
+.global _ZN3ams6nxboot6loader5StartEv
+.type   _ZN3ams6nxboot6loader5StartEv, %function
+_ZN3ams6nxboot6loader5StartEv:
+    /* Switch to system mode, mask all interrupts, clear all flags */
+    msr cpsr_cxsf, #0xDF
+
+    /* Relocate loader stub. */
+    ldr r0, =_ZN3ams6nxboot6loader5StartEv
+    adr r1, _ZN3ams6nxboot6loader5StartEv
+    ldr r2, =__loader_stub_lma__
+    sub r2, r2, r0
+    add r2, r2, r1
+
+    ldr r3, =__loader_stub_start__
+    ldr r4, =__loader_stub_end__
+    sub r4, r4, r3
+    0:
+        ldmia r2!, {r5-r12}
+        stmia r3!, {r5-r12}
+        subs  r4, #0x20
+        bne 0b
+
+    /* Set the stack pointer */
+    ldr  sp, =0x40001000
+    mov  fp, #0
+
+    /* Generate arguments. */
+    ldr r3, =program_lz4
+    ldr r4, =program_lz4_end
+    sub r4, r4, r3
+    sub r3, r3, r0
+    add r3, r3, r1
+    mov r0, r3
+    mov r1, r4
+
+    /* Jump to the loader stub. */
+    ldr r3, =_ZN3ams6nxboot6loader20UncompressAndExecuteEPKvj
+    bx  r3

fusee_cpp/loader_stub/source/fusee_loader_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_loader_uncompress.hpp"
+
+namespace ams::nxboot::loader {
+
+    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();
+    }
+
+}

fusee_cpp/loader_stub/source/fusee_loader_uncompress.hpp

@@ -0,0 +1,23 @@
+/*
+ * 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 <vapours.hpp>
+#pragma once
+
+namespace ams::nxboot::loader {
+
+    void Uncompress(void *dst, size_t dst_size, const void *src, size_t src_size);
+
+}