essence-os/help/Source Map.md

This file contains a list and description of the files and folders in the source tree.

• apps/ Builtin applications. Each application has an .ini file that is automatically detected by the build system.
  • samples/ Sample applications, demonstrating a small part of the API.
    • hello.c A hello world GUI application. Read through this first if you want to learn how to write applications for Essence!
    • converter.cpp A simple currency converter. Demonstrates panels, buttons, and textboxes.
    • game_loop.cpp A simple game loop. Demonstrates how to draw directly to the window with a custom UI element, and manually process keyboard input events.
    • list.cpp A sample of the fixed items mode of the list view.
  • file_manager/ The file manager application.
    • commands.cpp Implementation of commands like copy and paste.
    • folder.cpp Contains implementations of namespaces, like file system folders and the drives page.
    • main.cpp Main message loop, and settings management.
    • string.cpp String and path utilities.
    • type_database.cpp Management of file types.
    • ui.cpp Creates and manages the user interface. Contains the thumbnail generator.
• arch/ Contains target architecture specific files. Each architecture is placed in a separate folder, named after the target name. Note that some architecture specific code is also located in boot/. The folder will contain the following files:
  • kernel.s The assembly translation unit that will be linked with the kernel.
  • kernel.cpp The C++ translation unit that will be linked with the kernel. Together with kernel.s, this should provide all the functions listed in the architecture specific layer part of the kernel/kernel.h.
  • api.s The assembly translation unit that will be linked with the desktop. This must provide a system call interface, as well as a few miscellaneous functions.
  • config.ini Specifies additional compilation flags for the architecture.
• bin/ Contains the output of the build system that will not be copied onto the drive image.
  • Logs/ Contains various logs of the build processes and emulators.
    • net.dat Network packets captured and sent by Qemu.
    • audio.wav Audio captured by Qemu.
    • qemu_serial1.txt Serial output captured by Qemu.
    • system.log A list of commands passed to system() by util/build.c, including the time each command took.
  • cache/ Cached files downloaded from the internet, managed by the get-source command in the build system.
  • generated_code/ Automatically generated code.
  • build.ini The build configuration file that is passed from util/build.c to util/build_core.c. Save this if you want to automate a specific build.
  • build_config.ini The configuration file for util/build.c. Stores whether the user has read the license, and information about the cross compiler toolchain.
  • config.ini The configuration file modified by util/config_editor.c (open by running the config command in the build system). The full list of options in the file is stored in the options array in util/build_common.h.
  • dependencies.ini Saved information about source file dependencies used by the util/build_core.c for minimal rebuilds.
  • drive The output drive image, used to boot the emulators.
  • Additionally, there is an ELF executable file with debug symbols for each of the built applications, the desktop, the kernel and the build utilities.
• boot/ Contains boot code for different architectures, before the kernel is reached.
  • x86/ Boot code for x86 PC platforms.
    • mbr.s First stage of the MBR boot loader. Placed in the first sector of the drive.
    • mbr-emu.s An alternative version of mbr.s for CD-ROMs rather than hard drives.
    • esfs-stage1.s Second stage of the MBR boot loader. Placed in the first sector of the EsFS partition. Loaded by the first stage.
    • loader.s Third stage of the MBR boot loader. Placed in the reserved area of the EsFS partition. Loaded by the second stage.
    • esfs-stage2.s File system specific code for the third stage of the MBR boot loader.
    • vbe.s Contains code to select and set a video mode for the MBR boot loader; part of the third stage.
    • uefi.c First stage of the UEFI boot loader.
    • uefi_loader.s Second stage of the UEFI boot loader.
• cross/ Contains the cross compiler toolchain.
  • bin2/ When using the pre-built toolchain, wrappers of the executables in bin/ are stored here. These are needed to replace the system root path that was hard coded into the toolchain when it was configured.
• desktop/ TODO
• drivers/ Drivers linked into the kernel.
  • acpi.cpp Simple ACPI layer. Parses the MADT for loading other processors.
  • acpi_thermal.cpp ACPI thermal layer. Requires ACPICA.
  • acpica.cpp Integration with ACPICA, which provides greater ACPI functionality.
  • ahci.cpp AHCI/SATA drives.
  • bga.cpp Bochs Graphics Adapter, for setting the video mode on emulators.
  • esfs2.cpp The Essence file system (second version).
  • ext2.cpp Ext2 file system.
  • fat.cpp FAT12/16/32 file systems.
  • hda.cpp HD Audio.
  • i8254x.cpp i8254x networking card.
  • ide.cpp IDE/ATA drives.
  • iso9660.cpp ISO9660 file system for CD-ROMs.
  • ntfs.cpp NTFS file system.
  • nvme.cpp NVMe drives.
  • pci.cpp PCI bus enumeration.
  • ps2.cpp PS/2 keyboard and mouse.
  • rtc.cpp x86 Real Time Clock.
  • svga.cpp (S)VGA graphics drivers.
  • usb.cpp Common USB management for connecting and identifying devices.
  • usb_bulk.cpp USB bulk mass storage drives.
  • usb_hid.cpp USB HID class devices, including keyboards, mice and game controllers.
  • xhci.cpp xHCI USB controller driver.
• help/ You are here! Contains documentation about the project.
• kernel/ TODO
• ports/ Ported application, including dependencies.
• res/ Resources, such as fonts and images.
  • Fonts/ Fonts. Licenses are contained in this folder.
  • Keyboard Layouts/ Keyboard layouts. Contains a license file, and extract_keymaps.c which can be used to generate the keyboard layout files here from an X11 system.
  • Sample Images/ Sample images. Contains a license file. Copy these into root/ to access them from the built system.
  • Theme Source.dat The source for the theme file, used by util/designer2.cpp. Open with the designer command in the build system.
  • Theme.dat The exported theme file that will be used by the UI. Call bin/designer2 export to regenerate this from the theme source.
  • elementary Icons.dat The elementaryOS icons pack. The icon pack is a custom format, and is generated by util/render_svg.c.
• root/ Contains the output of the build system that will be copied onto the drive image. You can put any files you want to be copied onto the drive in here.
• shared/ Shared code between different parts of the proejct, including data structures.
  • esfs2.h Definitions for the Essence file system, and code for managing it (compiled into util/build_core.c).
  • ini.h A tiny INI file parser.
  • arena.cpp A memory allocator for arbitrary allocation and freeing of fixed size memory blocks.
  • array.cpp Dynamically allocated array.
  • avl_tree.cpp AVL lookup tree, including support for searches for the "smallest above or equal" and "largest below or equal".
  • bitset.cpp Efficient large bitsets.
  • common.cpp Various common functions, including management of EsRectangles, rendering, string utilities, memory utilities (like EsMemoryCopy), printing and string formatting, pseudo random number generation, standard algorithms like sorting, synchronisation primitives, byte swapping, implementation of the EsCRT- functions, EsBuffer functions, and time and date calculations.
  • fat.cpp Common definitions for the FAT file system.
  • hash.cpp Implementation of CRC32 and CRC64 hash functions.
  • hash_table.cpp A hash table, including an implementation of the FNV1a hash function.
  • heap.cpp A memory allocator for arbitrary allocation and freeing of non-fixed size memory blocks.
  • linked_list.cpp Two implementations of a doubly-linked list: LinkedList<T> and SimpleList<T> where the latter requires less memory but provides less features.
  • math.cpp Mathematical functions, including basic utilities, interpolation routines, HSV color conversions, standard trigonometric functions, high precision floating-point calculations, and an expression parser.
  • partitions.cpp Contains routines to manage MBR and GPT partition tables.
  • png_decoder.cpp A decoder of PNG image files.
  • range_set.cpp Efficiently stores a subset of the integers as a list of ranges.
  • strings.cpp All text displayed in the user interface of the built-in applications.
  • unicode.cpp Implementations of various Unicode standards, including UTF-8 decoding and validation, and the line breaking algorithm.
  • vga_font.cpp A fixed-width bitmap font.
• util/ Contains utilities for developing and building the project.
  • linker/ Contains linker scripts.
  • w32/ The experimental W32 backend for the Essence desktop.
  • build_common.h Common definitions shared between build.c and build_core.c.
  • luigi.h A single-header cross platform GUI library.
  • build.c The main build system prompt, which manages dependencies, the toolchain, build configurations, and launching emulators. It is accessed by the developer by running the start.sh script at the root of the source tree. The developer can then issue commands to build and test the operating system and other utilities.
  • build_core.c The heart of the build system, which actually builds the project. It is called by build.c, and passed a build configuration file in bin/build.ini which contains all possible configuration options. It can run within Essence. It is also able to build single applications, by passing the .ini file for that application.
  • change_sysroot.c A utility that uses ptrace to replace strings in system calls.
  • toolchain_wrapper.c Wraps the executables in the pre-built toolchain to call into change_sysroot.c, to change the system root path they use.
  • config_editor.c A graphical editor for the configuration file, bin/config.ini. Uses luigi.h.
  • font_editor.c A basic bitmap font editor. Uses luigi.h.
  • header_generator.c Generates the API header for different programming languages from desktop/os.header. Part of build_core.c.
  • render_svg.c Converts SVGs to an internal format for vector graphics, and creates the icon pack found in res/. Despite the name this does not actually render the SVGs to bitmaps! That is eventually done in api/renderer.cpp.
  • designer2.cpp An editor of theme files for the UI. Uses luigi.h.
  • uefi.sh Creates a drive image using the UEFI boot loader.
  • uefi_compile.sh Compiles the UEFI boot loader.
  • uefi_to_device.sh Formats a real device to use the UEFI boot loader.
  • api_table.ini A list of all the functions exposed by the API, and their corresponding ordinals. Managed by header_generator.c.
  • test.txt A file containing a few traps that might be mangled by source control or compression utilities. Verified by start.sh to ensure that the source is as we'd expect.