SNESDEV

This morning on my train trip to work, I finally got the ‘on the fly’ patching of a commercial ROM. The Rom I’m using is the original Street Fighter II game. What I do is defining a breakpoint at 0×00812f and output a register dump with BSnes. Here are the 2 log files.

Internal BSnes log file :

devkit::power() : On
Patcher::power() On
Patcher::isBreakpoint() On
Patcher::isBreakpoint() PC Backup : 00812F
Patcher::isLifePatchingDone() addr : 81BE baseAddr : 812F size : 008E
Patcher::isLifePatchingDone() New addr : 812F
Patcher::isBreakpoint() Reset lifePatchingDisableOnce
Patcher::isBreakpoint() On
Patcher::isBreakpoint() PC Backup : 00812F
Patcher::isLifePatchingDone() addr : 81BE baseAddr : 812F size : 008E
Patcher::isLifePatchingDone() New addr : 812F
Patcher::isBreakpoint() Reset lifePatchingDisableOnce
Patcher::isBreakpoint() On
Patcher::isBreakpoint() PC Backup : 00812F
Patcher::isLifePatchingDone() addr : 81BE baseAddr : 812F size : 008E
Patcher::isLifePatchingDone() New addr : 812F
Patcher::isBreakpoint() Reset lifePatchingDisableOnce
Patcher::isBreakpoint() On
Patcher::isBreakpoint() PC Backup : 00812F
Patcher::isLifePatchingDone() addr : 81BE baseAddr : 812F size : 008E
Patcher::isLifePatchingDone() New addr : 812F
Patcher::isBreakpoint() Reset lifePatchingDisableOnc

External log outputting register Dump :

Debug Command : 0x01

*************************
*** Register Dump. ******
*************************
A : 0x0000
X : 0x0001
Y : 0x000E
Direct Page      : 0x0000
Data Bank        : 0x31
Processor Status : 0x07
*************************

Debug Command : 0x01

*************************
*** Register Dump. ******
*************************
A : 0x20C2
X : 0x3101
Y : 0x20C2
Direct Page      : 0x0000
Data Bank        : 0x31
Processor Status : 0x07
*************************

Debug Command : 0x01

*************************
*** Register Dump. ******
*************************
A : 0x101F
X : 0xB101
Y : 0x101F
Direct Page      : 0x0000
Data Bank        : 0x31
Processor Status : 0x07
*************************

Debug Command : 0x01

*************************
*** Register Dump. ******
*************************
A : 0x0416
X : 0x3101
Y : 0x2016
Direct Page      : 0x0000
Data Bank        : 0x31
Processor Status : 0x07
*************************

I stopped Bsnes at the main screen of Street Fighter II. That means that address 0×00812f is executed 4 times.

Next step is … ‘Step by Step’ debugging. I would like to get an interactive console to set/remove breakpoint, dump register with a command and execute next instruction. The problem is that I don’t know how to implement that within Bsnes. If someone got any ideas, just post a comment with them. I really would avoid to made a GUI with that inside Bsnes. The ideal solution would be to have an external program that can send data to Bsnes with instruction encoded in a binary format.

See ya, lint

This entry was posted on Wednesday, June 24th, 2009 at 4:59 pm and is filed under Snes, Software dev. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.