Debugger

So I ran into a bug yesterday where I believe a shift is being done incorrecly, and leaving a multiplication result negative. This occurs on a register that stores a count variable, so it never hits zero and I run into a loop which doesn't break until a data abort.

I could easily find the cause of this, but I decided to postpone it for the day to think about a feature I wanted to add to the emulator's debugger: symbol lookup. Currently, if I want to set a breakpoint I have to enter in the exact address, which is fine, but when I just want to jump to a function without having to go through anything else, I essentially have to run the program twice; once to get the address of the function, and the other to actually debug it. Now, I could calculate this just by looking at the binary, as that's just awesome and fun, but if I want this to be used, I don't think I want to force that.

Symbol tables in this case are complex. First of all, each binary has a number of different sections, and symbols are local to sections. Therefore, duplicate naming must be taken into account, so I need to probably prompt the user of the debugger for all possible choices if there are any, when they want to break at a symbol. Furthermore, there are many different binaries that are in use by the emulator. You have the BIOS, which loads the firmware, which can load the Pictochat program or a game. You can't just have one giant symbol table for all these binaries, but at the same time, you have to make some sort of distinction. I think what I'm going to do is just allow only one binary to be debugged for now...how that will be specified is a challenge for a later date. What needs to be done now is modifying my assembler/linker to place the symbols in the binary and classify it as a "debug" binary, instead of a raw one.