Gens/GS r7

Copyright (c) 1999-2002 by Stéphane Dallongeville
Copyright (c) 2003-2004 by Stéphane Akhoun
Copyright (c) 2008-2009 by David Korth

This version of Gens is maintained by David Korth.
E-mail: gerbilsoft@verizon.net

For news on Gens/GS, visit Sonic Retro:
http://www.sonicretro.org

================================================================

What is Gens/GS?

Gens/GS r7 is David Korth's fork of Gens, initially based on
Gens for Linux v2.15.2. The number after the "r" indicates the
Gens/GS release. Releases are usually made after a significant new
feature has been added, with minor releases if a major bug is found.

================================================================

NOTE: The MDP documentation and Gens/GS manual are not finished
in this version of Gens/GS. They will be completed in a future
release of Gens/GS.

================================================================

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.

================================================================

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 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.

* Fixed a regression with DMA from SegaCD Word RAM via the cell conversion
  table. This regression was introduced when I attempted to implement the
  VDP's 128k (64k-word) wrapping behavior. This regression didn't affect
  "Sonic CD", but it did affect "Heart of the Alien". Thanks to tetsuo
  from #retro for helping to diagnose and solve this problem.

* [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.

================================================================

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.

================================================================

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.

================================================================

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.

================================================================

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.