Gens/GS

Gens/GS is a version of Gens maintained by GerbilSoft. The main goal of Gens/GS is to clean up the source code and combine features from various forks of Gens, as well as improving portability to other platforms.

Coming Soon

Features currently being worked on for the next release (r7.1):

• [Win32] Full Unicode support on Windows NT. Additionally, ANSI strings on Windows 9x will be converted to UTF-8 for cross-platform compatibility. (Note that Windows 95 doesn't support UTF-8, so Windows 95 is no longer supported.)
• Physical CD-ROM drive abstraction layer. BIN/CUE support may be added, too.
  • ISO/MP3 and Linux CD-ROM support has been ported.
  • Win32 ASPI support is in progress.
• Shift-JIS title decoder for some Japanese ROMs.
• [Linux] IRC Reporter plugin to report the current ROM to IRC clients.
• New onscreen display font, based on UNI-VGA and GNU Unifont, with support for most of the Unicode Basic Multilingual Plane. (ASCII characters [U+0000 - U+007F] will be included in the binary, but all other characters will be stored in external custom font files.)
• [Linux] Initial VDP Debugging plugin with all the functionality currently available in the built-in VDP debugger, plus a sprite viewer and Sonic sprite mapping viewer.
  • Sprite viewer shows hardware sprites. [Not Started]
  • Sonic sprite mapping viewer shows full sprites using the mapping system found in Sonic games. [Not Started]
• The VDP rendering and I/O code is being ported from x86 assembly language to C++. Some notable improvements in this port:
  • The per-line sprite limit is now respected. (16 sprites per line in H32; 20 in H40.)
  • Border color is now rendered in the VDP code instead of in the video drawing backends.
  • V30 (240-line) resolution is now supported in NTSC. That is, it works like it does on the real console: VBlank is reduced to 30 Hz, and the picture rolls. (V30 still works normally in PAL.)
  • All tests in Nemesis' Sprite Masking and Overflow Test ROM now pass.
  • VDP ports are now correctly mirrored throughout the M68K's $C00000-$DFFFFF address space.
• SegaCD: The BRAM cartridge emulation now allows 128 KB, 256 KB, and 512 KB cartridges. (Default is still 64 KB)
• ROM images that use SRAM now have the SRAM initialized to 0xFF instead of 0x00. This fixes a few games, including Micro Machines 2 and Dino Dini's Soccer.
• The 2x C++ renderer no longer reads from the destination buffer when line-doubling the image. It also uses a single loop per source row instead of two.
• The 2x MMX renderers have been optimized to use a single loop for each source row instead of two.

Features planned for Release 7.2:

• Port the emulation code of mdZ80 to C.

Features that may be worked on for a future release, but aren't certain:

• Cheat Search plugin.
  • This makes it too easy for the average user to make a "hack" without knowing what they're doing, so it's unlikely that this plugin will be written by me. I will accept patches from anyone else who wants to write this plugin, however.

Release 7

Changes from r7_pre5 to r7:

New Features

• Added an additional color scaling method, "Full with S/H". This method takes into account the Shadow and Highlight functionality of the Sega Mega Drive's VDP. With this method, MD color 0xEEE (white) is scaled to 0xEEEEEE for normal, 0xFFFFFF for highlight, and 0x777777 for shadow. This color scaling method is now the default.
• Initial reimplementation of "Full Screen Minimize". This allows the emulator to minimize itself from Full Screen when a dialog is open, e.g. to load a ROM image. It is currently only usable for a specific case on the Linux version.
• [Linux] Added Alt-Tab support in Full Screen. This uses the "Full Screen Minimize" infrastructure.

Bug Fixes

• [Win32] Added a workaround for an ASPI-related crash on Windows 98SE.
• [Win32] Fixed a regression from r7_pre3 that caused Gens/GS to crash if a ROM is loaded via File, Open ROM and a Saitek P580 gamepad is plugged in. Special thanks to NeKit from Sonic Retro for helping to diagnose and solve this problem.
• [Linux] Fixed a regression from r7_pre4 where starting Gens/GS in fullscreen mode with a ROM specified wouldn't work. This bug was reported by Zombie in #retro.

Miscellaneous

• [Win32] The custom debug console activated with "--debug" on the release build has been replaced with a standard Win32 console, which is created after initial startup.
• [MDP] Implemented mdp_host_t->emulator_control(MDP_EMUCTRL_RELOAD_INFO).
• Added "Manual" and "Report a Bug" items to the Help menu.

Low-Level Code Changes

• [libgsft] Added an implementation of strsep() and removed the strtok_r() implementation. All Gens/GS code that uses strtok_r() has been switched over to strsep().
• [libgsft] Added the BSD implementations of strlcpy() and strlcat(). Most Gens/GS code has been switched over to these functions.
• Initial infrastructure for dynamically loading libpng. This will be used to separate libpng on Gens/GS Win32 into a separate DLL. If libpng can't be found, Gens/GS will fall back to saving screenshots in BMP format.
• Eliminated most of the "DECL" macros from the x86 assembler files. This reduces the total symbol count in the resulting binaries.
• Added a new x86 assembler macro, SYM(), which prefixes symbols with the appropriate C symbol prefix for the platform.

Release 7, Preview 5

Changes from r7_pre4 to r7_pre5 [PREVIEW RELEASE]:

New Features

• The on-screen display text drawing code has received several changes:
  • The text is now cached using the C64 character set data to reduce the time needed to draw the text on every frame.
  • The 1x and 2x text drawing functions have been consolidated into one templated function.
  • UTF-8 strings are now supported. Invalid UTF-8 sequences are treated as local codepage characters.
  • More characters were added to the C64 character set to take advantage of UTF-8 support.
• The menu bar can now be hidden in windowed mode. To access the menu system in windowed mode while the menu bar is hidden, right-click anywhere in the Gens/GS window.
• Added an RGB Color Scaling option. This option scales colors to their full brightness, which is accurate with regards to how the original console worked. For example, on the MD, a color component 0xE indicates full brightness; however, on Gens/GS in 32-bit color, this would get scaled to 0xE0 (224) instead of 0xFF (255). With Color Scaling on, it is now properly scaled to full brightness.

Bug Fixes

• [SDL] Fixed a controller input regression that inverted axes. This regression was introduced in r7_pre4 with the reworking of the SDL key configuration handler to make it ignore the initial joystick state when detecting joystick changes. This bug was reported by superGear in #retro.
• [SDL] Fixed a bug in Controller Configuration where POV hats weren't read properly. This bug was reported by dmb in #retro.

Miscellaneous

• A new utility called "CBOB" (C Binary Object Builder) is used to convert the reverse-engineered Sega 32X firmware images into C arrays at compile time. This eliminates the need to have a pre-converted source code file, plus it makes it easier to update the included firmware images (and add more built-in binaries) at a later date.

Release 7, Preview 4

Changes from r7_pre3 to r7_pre4 [PREVIEW RELEASE]:

New Features

• [Win32] The release build of Gens/GS for Win32 has the standard Win32 console disabled. A new Gens/GS-specific debug console has been added for the release build. This console can be enabled by specifying "--debug" on the command line.

Bug Fixes

• [Unix] Starting Gens/GS with the "--fs" option or "Full Screen=1" in the configuration file works properly. Previously, the GTK+ UI would be created after SDL was set to fullscreen, which caused SDL to revert to windowed mode, resulting in all sorts of screwiness.
• Blargg's NTSC Filter, MDP Version 1.1.1. This fixes two major bugs:
  • v1.1.0: Don't read from VRAM for line-doubling, since this is slow on Windows.
  • v1.1.1: Draw the last scanline correctly when interpolation is enabled.
• [Win32] The "Screenshot" menu item was being checked/unchecked instead of enabled/disabled in the menu synchronization function. This bug was reported by AamirM in #retro.
• [SDL] Controller configuration now checks the current state of the controllers before polling for new keys. This makes it easier to configure controllers that have analog triggers whose default state is negative-axis.
• [SDL] Gens/GS now recognizes diagonals on POV hats properly. This bug was reported (and fixed) by superG on the Ubuntu Forums.
• Fixed the "Crazy" and "Gens Logo" intro effects so they work again. The intro effect is now configurable in the "General Options" window. Note that the "Gens Logo" effect may have problems on Win32 if the desktop color depth doesn't match the rendering color depth.
• The "Directory Configuration" window now correctly shows the directory names in the "Select Directory" window title. This regressed when the "Directory Configuration" window was ported back to C in r7_pre1.
• [Win32] If the "Normal" renderer can't be initialized in Full Screen in the DirectDraw renderer, try the "Double" renderer instead. Some newer Windows video drivers don't support double-scanning 320x240, so 640x480 must be used instead.
• [Win32] Fixed a massive lag regression from the "back-to-c" branch. The DirectSound audio backend was sleeping for 1 ms while waiting for the write pointer to change, which caused issues with the Windows scheduler on some systems. Thanks to djohe from #retro for helping to diagnose and solve this problem.
• [Win32] Removed a call to ChangeDesktopSettings() on exit. Notably, this fixes a bug in Wine where Gens would disable the second monitor on exit. It probably also fixes some flicker issues on Vista when the program exited.
• SRAM functionality was accidentally broken in Release 7, Preview 2. I overhauled the ROM header parser but forgot to byteswap various values, including the SRAM addresses. SRAM works now.

Miscellaneous

• automake-1.10 is now required to build Gens/GS.
• The "Double" renderer is now default for both Full Screen and Windowed modes.
• Stretch mode now defaults to "Horizontal Only".
• [Win32] Window reinitialization has been improved when switching to/from Full Screen. The reinitialization code from the DirectDraw 4 and GDI renderers has been merged into a single function.
• [Win32] The Release build now has an option for a debug console. To enable the debug console, specify the "--debug" parameter on the command line.
• Incompatible MDP plugins are now displayed in a third tab in the Plugin Manager window. The description field displays the MDP error code.
• [Ubuntu] The Ubuntu package no longer includes static libraries and libtool files (.a and .la, respectively) for MDP plugins, since they're useless. External MDP plugins can't be linked at compile-time.

Release 7, Preview 3

Changes from r7_pre2 to r7_pre3 [PREVIEW RELEASE]:

New Features

• [Unix] If a game has a Shift-JIS encoded title in the Japanese title field and the country code is set to Japan, the title will be converted to the system's native locale, e.g. UTF-8. (Win32 support for this feature will be added once Gens/GS fully supports Windows' Unicode implementation.)
• [Unix] On systems that support sigaction(), the signal handler dialog will now show extended signal information for some signals, e.g. SIGFPE.

Bug Fixes

• Several buffer overflow bugs that caused crashes in the release build on some Linux platforms have been fixed. This includes a long-standing bug in the SegaCD code, plus a new bug in the partially-rewritten savestate loading code.

Release 7, Preview 2

Changes from r7_pre1 to r7_pre2 [PREVIEW RELEASE]:

New Features

• A new command line option, "--boot-cd", can be specified to tell Gens/GS to boot from an actual SegaCD CD-ROM on startup.
• Gens/GS no longer changes non-alphanumeric characters in SegaCD game names to spaces. This may cause some games to have different names, which will prevent their BRAM files from being loaded properly. If you have any of these games, you will need to rename the BRAM files in order to get them to load correctly.

Miscellaneous

• MDP v1.0.0 has been marked as "stable", and will not have any further API/ABI-breaking changes.

Release 7, Preview 1

Changes from Milestone 6 to r7_pre1 [LIMITED PREVIEW RELEASE]:

New Features

• Mega Drive Plugins v1.0.0. This major update to the plugins system adds support for external plugins (.dll on Windows, .so on Linux), as well as support for more than just rendering plugins.
• doc/mdp/ contains the MDP Interface Specifiction Version 1.0.0. This document is licensed under the GNU Free Documentation License v1.3.
• A new manual for Gens/GS has been created. It is available in doc/manual/.
• The Game Genie functionality has been moved to an MDP plugin. It now supports 8-bit, 16-bit, and 32-bit patch codes, and uses a new patch code file format. Old patch code files are supported for loading; however, they will be written in the new format when saved. Later versions will add support for patching CPU address spaces other than the main MC68000.
• New MDP Plugin: VDP Layer Options. This lets you adjust the visible layers on screen, so e.g. you can hide sprites, swap scroll priorities, and lock the palette to prevent color changes.
• New MDP Plugin: Sonic Gens. This lets you view various information in memory in several Sonic games. Sonic Gens was originally written by LOst as a standalone version of Gens.
• New renderers:
  • EPX (ported from Gens Rerecording)
  • EPX Plus (ported from Gens Rerecording)
  • Super 2xSaI (ported from Gens Plus)
  • Super Eagle (ported from Gens Plus)
  • Blargg's NTSC filter for MD
• [Win32] Ported the GDI video backend from Gens Plus. It still has a few bugs, but it mostly works.
• Extended controller configuration format. The new configuration format allows for up to 128 axes, 256 buttons, and 64 POV hats, whereas the old configuration format only allowed for 6 axes [5 axes on Win32], 112 buttons, and 4 POV hats. This mainly affects the Linux version, since Linux usually reports all axes as axes instead of mapping some axes to POV hats, and some newer controllers (e.g. the Xbox 360 controller) have more than 6 axes. Older configurations are automatically updated to use the new controller configuration format.
• The reverse-engineered 32X firmware, written by DevSter, is now included in Gens/GS. If you do not have the original Sega 32X firmware files, the reverse-engineered ones are used instead.
• Added SH2 DMA support for PWM audio. Thanks to Joseph Fenton for submitting a patch.
• [Win32] Joysticks connected after loading Gens/GS will now be detected in the Controller Configuration dialog.
• WAV dumping has been reimplemented.
• ROM History now caches the ROM type (MD/MCD/32X), so it doesn't have to check the ROM type every time the ROM History menu is rebuilt. This improves performance significantly if some ROM images were loaded from network shares.
• ROM History now keeps track of compressed files inside of multi-file archives. For example, if you have a 7z archive containing several different versions of a game, selecting version 1 will result in a ROM History entry for that specific version, and selecting version 2 will result in another ROM History entry.
• Added initial support for the "Palette Select" bit in VDP register 0. If the "Palette Select" bit is cleared, only the LSBs of each color component in CRAM is used to determine the colors to display, resulting in a maximum of 8 colors onscreen. This isn't very useful, but it's more accurate.
• SRAM can now be disabled in the Options menu. This fixes Puggsy, which checks for the existance of SRAM and prevents the user from advancing past a certain point if it exists. (Puggsy uses a password system, not SRAM.)
• [Unix] Improved VSync support with the OpenGL backend. Both the MESA and SGI swap control methods are now supported.
• The video subsystem now supports fallbacks. For example, on the Linux version, if SDL+OpenGL is selected but OpenGL isn't available, it will simply revert back to SDL instead of crashing. As an added bonus, this allows for Gens/GS to start up properly on Windows NT 4.0, since the default backend on Win32 is DirectDraw 4, but NT4 doesn't support it. Instead of crashing, it will fall back to the GDI backend.

Bug Fixes

• Dragging and dropping a ROM image onto the Gens/GS window will now synchronize the menus. This bug was reported by Tets on the Sonic Retro forums.
• Loading a GSX savestate file that is not in GSX format will now show an error instead of crashing. Apparently, Gens Plus GZips its savestate files when saving by default. This bug was reported by SoNick in #retro.
• [GTK+] Copied g_uri_unescape_string() (and dependent functions) from GLib 2.18.4 into Gens/GS. This function was introduced in GLib 2.16, but Gens/GS should be compatible with versions of GLib 2.4 and later.
• Two VDP DMA bugs have been fixed:
  • Zero-length DMA operations are now handled as 65,536-word operations. This may break some badly-written hacks.
  • DMA operations now wrap on a 128k boundary. This bug was reported by TmEE.
• The VDP H_Int register is now initialized to 0xFF. This fixes Sik's test ROM that produced "rain" on Gens, but not on Regen or the actual hardware.

Low-Level Code Changes

• The video, audio, and input subsystems have been ported back to C. The C++ system was too awkward and had too much overhead.
• Similarly, the decompression subsystem has been ported back to C. In addition, the LZMA SDK is now built into Gens/GS, so 7z archives can be read without an external 7z binary.
• Initial port of the Z80 emulator to C. The Z80 emulator has been moved out of the src/gens directory and into its own directory, src/mdZ80. Currently, the only functions that have been ported to C are the helper functions. The actual emulation code is currently being worked on in the mdZ80 branch in the Gens/GS git repository.
• Many x86 assembly language files have been converted from Intel-style (nasm) assembly to AT&T-style (GNU `as`) assembly.
• Many assembler functions have been ported to C/C++, including the UPDATE_PALETTE macros and Reset_VDP() (now VDP_Reset()).
• Multitap support has been ported from x86 assembler to C. In the process, both Sega Teamplayer and 4-Way Play support have been improved. Notably, Teamplayer now works on "NBA Jam" and "NBA Jam TE", and 4-Way Play now works (sometimes) on "Triple Play '96". A complete list of tested multitap games can be found in doc/teamplayer.txt .
• yasm is now supported as an alternative to nasm. To use yasm, add the option --with-nasm=yasm when using the ./configure script.
• Precompiled binaries are now compiled for i686 or higher. If you want to run Gens/GS on an original Intel Pentium or older, you will have to compile your own Gens/GS binary.

For information about previous releases, see the ChangeLog.txt file included with Gens/GS r7_pre3.

Download

Git Repository

The Gens/GS git repository is available at http://gs_server.gerbilsoft.ddns.info/cgi-bin/gitweb.cgi?p=gens.git;a=summary .

Prior Versions

Release 7

• Gens/GS Release 7 (Win32, i386) ^(info) () (2.66 MB, released 2009/11/22)

Release 7 Previews

• Gens/GS Release 7, Preview 5 (Source Code) ^(info) () (2.31 MB, released 2009/10/11)
• Gens/GS Release 7, Preview 5 (Ubuntu 8.04+, i386) ^(info) () (1.14 MB, released 2009/10/11)
• Gens/GS Release 7, Preview 5 (Win32, i386) ^(info) () (1.53 MB, released 2009/10/11)
• Gens/GS Release 7, Preview 4 (Source Code) ^(info) () (2.21 MB, released 2009/09/12)
• Gens/GS Release 7, Preview 4 (Ubuntu 8.04+, i386) ^(info) () (1.08 MB, released 2009/09/12)
• Gens/GS Release 7, Preview 4 (Win32, i386) ^(info) () (1.46 MB, released 2009/09/12)
• Gens/GS Release 7, Preview 3 (Source Code) ^(info) () (2.04 MB, released 2009/08/02)
• Gens/GS Release 7, Preview 3 (Ubuntu 8.04+, i386) ^(info) () (991 KB, released 2009/08/02)
• Gens/GS Release 7, Preview 3 (Win32, i386) ^(info) () (1.35 MB, released 2009/08/02)
• Gens/GS Release 7, Preview 2 (Source Code) ^(info) () (2.04 MB, released 2009/07/29)
• Gens/GS Release 7, Preview 2 (Ubuntu 8.04+, i386) ^(info) () (800 KB, released 2009/07/29)
• Gens/GS Release 7, Preview 2 (Win32, i386) ^(info) () (1.33 MB, released 2009/07/29)

Milestone 6

• Gens/GS Milestone 6 (Source Code) ^(info) () (1.45 MB, released 2008/12/07)
• Gens/GS Milestone 6 (Ubuntu 8.04+, 32-bit) ^(info) () (622 KB, released 2008/12/07)
• Gens/GS Milestone 6 (Win32) ^(info) () (855 KB, released 2008/12/07)

Milestone 5.3 and earlier

• Gens/GS Milestone 5.3 (Source Code) ^(info) () (1.35 MB, released 2008/11/16)
• Gens/GS Milestone 5.3 (Ubuntu 8.04+, 32-bit) ^(info) () (582 KB, released 2008/11/17)
• Gens/GS Milestone 5.3 (Win32) ^(info) () (756 KB, released 2008/11/16)

• Gens/GS Milestone 5.2 (Source Code) ^(info) () (1.35 MB, released 2008/11/16)
• Gens/GS Milestone 5.2 (Ubuntu 8.04+, 32-bit) ^(info) () (582 KB, released 2008/11/16)
• Gens/GS Milestone 5.2 (Win32) ^(info) () (756 KB, released 2008/11/16)

• Gens/GS Milestone 5.1 (Source Code) ^(info) () (1.35 MB, released 2008/11/02)
• Gens/GS Milestone 5.1 (Ubuntu 8.04+, 32-bit) ^(info) () (579 KB, released 2008/11/02)
• Gens/GS Milestone 5.1 (Win32) ^(info) () (754 KB, released 2008/11/02)

• Gens/GS Milestone 5 (Source Code) ^(info) () (1.33 MB, released 2008/10/26)
• Gens/GS Milestone 5 (Ubuntu 8.04+, 32-bit) ^(info) () (578 KB, released 2008/10/26)
• Gens/GS Milestone 5 (Win32) ^(info) () (746 KB, released 2008/10/26)

• Gens/GS Milestone 4.2 ^(info) () (601 KB, released 2008/09/17)
• Gens/GS Milestone 4.1 ^(info) () (601 KB, released 2008/09/16)
• Gens/GS Milestone 4 ^(info) () (602 KB, released 2008/09/15)
• Gens/GS Milestone 3 ^(info) () (613 KB, released 2008/09/02)
• Gens/GS Milestone 2.2 ^(info) () (604 KB, released 2008/08/30)
• Gens/GS Milestone 2.1 ^(info) () (607 KB, released 2008/08/29)
• Gens/GS Milestone 2 ^(info) () (605 KB, released 2008/08/29)
• Gens/GS Milestone 1 ^(info) () (446 KB, released 2008/08/26)

Other Information

Trivia

• A parody version of the emulator, Gens/GS S2HD Edition, was released to mock the high overhead and bad effects of modern-day emulation compilations and poor-quality "HD" remakes.

Forum Threads

• Ubuntu Forums thread (r7_pre2)
• 
  Sonic Retro thread (r7_pre2)

Older Forum Threads

• Ubuntu Forums thread (m5-m6)
• Ubuntu Forums thread (m4.2)
• 
  Sonic Retro thread (m6 and earlier)