DS2x86 version 0.25 released!

October 23rd, 2011, 23:42 Posted By: wraggster

via http://dsx86.patrickaalto.com/

[h=4]Version 0.25 Release Notes[/h]First off, sorry for the stupid bug that crept into the previous version. I copied some paging-enhancements to several string opcodes, and forgot to change the jump address in one of the code clips I copied, so that when the game tries to move unaligned 16-bit values in memory, it actually jumps to a code that moves 32-bit values. This means that too much data is copied, overwriting something in memory, which in turn causes either erratic behaviour or in many cases a blue screen crash. I use Doom as my sanity-check game, and always test that I haven't broken the code completely before release by running it for a while. However, Doom did not happen to use this unaligned memory copy, so I did not find this problem before the release.

All in all, this version is mostly just a maintenance version and has the following improvements:

• Fixed a copy-paste bug in REP MOVSW string opcode (as mentioned above). This fixes the BSOD in Heretic, Hexen, and various problems in many other games.
• Implemented INT10 calls AX=1008 (READ OVERSCAN (BORDER COLOR) REGISTER), AH=12/BL=34 (ALTERNATE FUNCTION SELECT (VGA) - CURSOR EMULATION), AH=F1/DX=0020 (EGA Register Interface Library - WRITE ONE REGISTER - Miscellaneous Output register), AH=F1/DX=0028 (EGA Register Interface Library - WRITE ONE REGISTER - Feature Control register).
• Implemented missing 66-prefix variations for LFS and LGS opcodes (NORM).
• Implemented missing RCL and RCR opcodes using 32-bit registers (SWS).
• Implemented read/write to/from CPU debug registers (RAYMAN).
• Enabled directory access using the alias of a long directory name. I had to hack into the DSTwo SDK directory.c source to enable this. I compared the source with the current NDS libFAT sources (which it is based on), and found a difference. In the DSTwo SDK version the check if the directory alias (the short 8.3 version of the long name) matches the requested directory name was simply commented out. I have no idea why, and hopefully my re-enabling this feature does not cause any new problems in file and directory handling. It is always rather scary changing the low-level file access library functions.
• Ignore writes to I/O ports 0x140..0x14F (DESCENTR).

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