Genesis Plus SDL v1.4.1 - 模擬器

A very basic Win32 port, using SDL (with sound & keyboard support), based
on the current GX core (FOR TESTING PURPOSE ONLY)

http://code.google.com/p/genplus-gx/

Changelog:

[Core/Sound]
---------------
* implemented Blargg's blip buffer in SN76489 core (all channels are now
lineary interpolated)

[Core/VDP]
---------------
* improved 2-cell vscroll emulation accuracy, as verified on real hardware
(Gynoug, Cutie Suzuki no Ringside Angel, Formula One, Kawasaki Superbike
Challenge)
* improved VBLANK flag accuracy, as observed on real hardware.
* improved DMA operations accuracy, writes are now performed on a scanline
basis: fixes Gaiares (flickering title screen).
* improved DMA Fill timing accuracy.
* fixed DMA with bad code values: fixes Williams Arcade Classics (corrupted
gfx after soft reset).
* fixed horizontal resolution changes during HBLANK: fixes Bugs Bunny in
Double Trouble (2nd stage).
* fixed Vertical Counter in interlace mode 1, as observed on real hardware.
* fixed horizontal border width, as observed on real hardware.
* various code improvments & optimizations.

[Core/CPU]
---------------
* fixed state of Z80 registers on reset (sound issues with Defender &
Defender 2 in Williams Arcade Classics)
* implemented 68k undocumented flags behavior for DIVU/DIVS instructions
(Bloodshot / Battle Frenzy)

[Core/Extra]
---------------
* improved emulation of copy-protection hardware found in some unlicensed
cartridges (Mulan, Pocket Monsters II).
* enabled simultaneous use of multitap & J-CART (Super Skidmarks 6-player
mode)
* improved savestate format: added DMA, SVP, cartridge mapping & internal
registers state informations
* improved unlicensed ROM mappers emulation
* added Chinese Fighters III mapper support
* added Top Fighter mapper support
* fixed Barver Battle Saga mapper support
* fixed cartridge hardware soft-reset (Game Genie, SVP, ...)
* fixed Game Genie registers byte reads


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