Difference between revisions of "Windows Tiny Intro"

Revision as of 04:27, 13 April 2024

Introduction

This category is for the tiniest Windows-32 intros, that often use custom Windows PE header in combination with CPU software rendering.

Tools

Assembler: NASM

Re-using Windows Header

The minimum Windows PE Header size on modern systems (Windows7 and up) is 268 bytes, even though part of this header is useless padding. So whilst it is perfectly possible to do a small graphical effect within thatn 268 byte limit by re-using part of the header, doing anything smaller than this lower limit is only possible on older Windows versions like Windows XP.

PE Header Structure

Here is the windows header structure:

                 ORG	0x400000
 base:
                 DW 'MZ'       ; 00. e_magic
                 DW 0          ; 02. e_cblp                        ; UNUSED
                 DD 'PE'       ; 04. Signature

                 ; COFF header
                 DW 014CH      ; 08. Target Machine (Intel 386)
                 DW 0          ; 0A. NumberOfSections (use 1 for overlapping section)
                 DW 0,0        ; 0C. TimeDateStamp                 ; UNUSED  
                 DW 0,0        ; 10. PointerToSymbolTable          ; UNUSED
                 DW 0,0        ; 14. NumberOfSymbols               ; UNUSED
                 DW 8          ; 18. Size Of Optional Header
                 DW 2          ; 1A. Characteristics (2 = IMAGE_FILE_EXECUTABLE_IMAGE)
                 
                 ; Optional header
                 DW 010BH      ; 1C. Magic (PE32 32bit EXE)
                 DW 0          ; 1E. Major+MinorLinkerVersion      ; UNUSED
                 DW 0,0        ; 20. SizeOfCode                     ; UNUSED
                 DW 0,0        ; 24. SizeOfInitializedData          ; UNUSED
                 DW 0,0        ; 28. SizeOfUninitializedData        ; UNUSED
                 DD start-base ; 2C. AddressOfEntryPoint
                 DD 0          ; 30. BaseOfCode                     ; UNUSED
                 DD 0          ; 34. BaseOfData                     ; UNUSED

                 ; Windows specific fields
                 DD base       ; 38. ImageBase
                 DD 4          ; 3C. SectionAlignment (.e_lfanew / PE offset +4)
                 DD 4          ; 40. FileAlignment
                 DD 0          ; 44. Major+MinorOperatingSystemVersion   ; UNUSED
                 DD 0          ; 48. Major+MinorImageVersion             ; UNUSED
                 DW 4          ; 4C. MajorSubsystemVersion               ; (use 3 of 4)
                 DW 0          ; 4E. MinorSubsystemVersion               ; UNUSED
                 DD 0          ; 50. Win32VersionValue                   ; UNUSED
                 DD 0          ; 54. SizeOfImage (malloc)                ; UNUSED
                 DD 30H        ; 58. SizeOfHeaders
                 DD 0          ; 5C. CheckSum                            ; UNUSED/UNCHECKED
                 DW 2          ; 60. Subsystem (Win32 GUI)
                 DW 0          ; 62. DllCharacteristics
                               ; 64. SizeOfStackReserve  (program entry)
 start:
                 ; Program entry
                 ; Padding to 268 bytes (minimal exe file length for Win7+)

Importing Functions

An important part of doing your own Windows Header management is that you will need to import functions manually. This can be done via header import, Import by Ordinal (specific to a windows version) or Import by hash.

Graphics

For 512 bytes, there are 2 ways to go about rendering graphics:

• CPU Software Rendering
• Minimal OpenGL/GLSL Rendering

Sound

There are a few ways to producing sound/music in Tiny Windows Intros.

Win32 Single Note MIDI

Using the built-in MIDI, this requires just 2 calls

• midiOutOpen(midihandle, 0,0,0,0) - To initialise the MIDI
• midiOutShortMsg(midihandle, 0x209035C0) - 4 byte Midi message that sets instrument + plays a single note on channel 0

For a full list of Midi commands, check out this webpage: https://computermusicresource.com/MIDI.Commands.html

Win32 MIDI Player

Depending on the sound budget, you can think about including a small MIDI tune instead. Similar to the single note MIDI approach, but playing multiple notes from data on 1 or more different channels.

Bytebeat softsynth

An alternative option is to use a very simple Bytebeat softsynth (Check out https://bytebeat.demozoo.org if you are not familiar with the concept).

This requires an additional setup of the Win32 WaveOut callback, which can then be played and filled realtime with data.

For a taste of what is possible with small (<256 character) bytebeats formulas, check out one of the Bytebeat Music competitions from the Lovebyte parties, for example https://demozoo.org/parties/4760/#competition_18623

Compression

Compression for the smaller Windows Tiny Intros are tricky, but there have been some experiments using the Windows Cabinet Decompressor calls

These functions allow for MSZIP (deflate) and MSLZ content to be loaded from the binary as payload at the cost of a a few more win32 function imports. Well this might be a good solution for 512 byte intros, the tipping point for Crinkler compression at the moment lies at the 800-850 bytes mark give or take.

From cabinet library:

• CreateDecompressor(0x20000002, 0, &HDecompressor) - Create Decompressor object
• Decompress(HDecompressor, CompressedPayload, PackOutputSize, 0x11000, PackInputSize,0) - Decompress payload

512 byte intros for Windows

• New Ground (2019)
• The Grid by Tomcat (2019)
• The Hole by Tomcat (2019)
• Spherical by MX/Addict (2023)
• (R)evolution by MX/Addict (2024)
• Mixontil by Busy (2024)

256 / 268 byte intros for Windows

• Hello World for Windows
• Pixondex - Tiny 256 byte intro effect for Windows
• Xor pattern in 256 bytes

Other Resources

• Article about Making a 874 byte Windows EXE
• Tiny PE header information