To all: I read with interest the posts about the MI emulator. Not that I would ever remotely attempt such a thing (nervous laugh) or want to, but because of the interesting background information. I had, for some time, assumed that older versions of OS/400 were essentially written in MI, and newer versions in C++. I guess that's approximately correct? Anyway, I am working on an MI source debugger program, just as an interesting project. Not w r i t t e n in MI, but for the purposed of d e b u g g i n g MI. Sadly, programming is really now more a hobby for me than a vocation, since I am going into a different field. But I digress. Most of the usual debugger functions ("Find", "Set Breakpoint", etc.) didn't present too much of a problem. But, the "Single Step" exececution function is a big hurdle. It s h o u l d of course, cause the program to run exactly one MI instruction and then stop at the next instruction. If a branch instruction is encountered, such as "CmpBla(b) FieldA, FieldB / Eq (Equal-Branch-Point);", the program should stop at Equal-Branch-Point if the branch is in fact taken. This is what I cannot figure out how to do! My stab at "emulating" this function was to set a breakpoint at the NEXT sequential MI instruction from the instruction at which the program is currently stopped, then let the program continue to run (and stop at the next instruction). This of course works fine when the instruction stream is in fact executed perfectly in sequence, but of course that is often not the case, program branching being the "MI way" to support an IF/ELSE construct. SO: I hope I have explained the little problem clearly. Does anyone know how IBM does this, for example in the (OPM) "Start Source Debugger" (STRISDB) product. It obviously is possible. I thought about setting breakpoints for ALL instructions in the program. That would be overkill worthy of a politician (not saying which flavor)! Thanks, Rich Hart
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