sdcc/debugger SDCDB debugger ====================== Notes April 23, 2003 Martin Helmling added support for ddd GUI debugger. Code added to display assembly, set variables, and other commands to interface to ddd. From Martins email: in the attachment is my actual patch. The 'up' and 'down' stack commands are not implemented. But the features for 'ddd' to see bopth the c source and the assembler works, also the display of variables. Set variables are only implemented for basic types. Register variables can also displayed, but here I think a problem in the *.cdb file exists. Sometimes the register name not exists: S:LcacheTxAnalogValue$offset$1$1({1}SC:U),E,0,0 S:LcacheTxAnalogValue$i$1$1({1}SC:S),R,0,0,[] S:LcacheTxAnalogValue$val$1$1({4}ST__00020000:S),E,0,0 S:LcacheTxAnalogValue$value$1$1({1}SC:U),R,0,0,[] S:LcacheTxAnalogValue$sloc0$1$0({4}SL:U),E,0,0 S:LsetRelays$addr$1$1({1}SC:U),R,0,0,[r2] S:LsetRelays$state$1$1({1}SC:U),R,0,0,[r3] S:LsetRelays$value$1$1({1}SC:U),R,0,0,[r5] S:L_main$i$1$1({1}SC:U),R,0,0,[] S:L_main$j$1$1({1}SC:U),R,0,0,[r3] S:L_main$ok$1$1({1}SC:U),R,0,0,[r3] the empty [] I mean !! Is this a known bug in sdcc ? Also sometimes not the correct breakpoints for stepping found in sdcdb. I try to fix this tomorrow. Notes Feb 10, 2002 - Karl Bongers SDCDB is a debugger for SDCC compiler. It works as a front end to the ucSim simulator/disassembler program. WARNING: SDCDB is EXPERIMENTAL and NOT A FULLY FUNCTIONING TOOL. SDCDB does hold out promise for a nice debugger tool that could integrate well with ucSim and other SDCC tools. It has some nice functionality that could augment ucSim nicely. It reads in a lot of symbolic information from the .CDB debug files as well as the source code and assembly listings referred to in these CDB files. This can be used to display your program data, list c or asm source code and set breakpoints. Unfortunately, SDCDB is not quite finished and does not function well enough yet to recommend for general use. Usage Notes ====================== Compile with --debug option: sdcc --debug hi.c This should generate .cdb symbolic debug files. Load sdcdb, like this: sdcdb hi.ihx Then you need to do an initial "run" command. It should hopefully stop somewhere at the main() entrypoint. Now you should be able to list code, and set breakpoints. Type "c" to continue running to a breakpoint, or type "s" to single step or "n" to skip function calls. Tpye "help" for a summary of commands. Use a preceeding bang("!") to do s51 simulator commands. So for example: !pc will send the "pc" command to ucSim and give you the program counter and list the current line of assembly. !help will give you the brief command line help listing of ucSim. But this help will scroll of the screen. So to get a list, I redirect stdout to a text file to examine like this: sdcdb hi.ihx 2>&1 | tee sdcdb.log Type '.' to toggle to a full time ucSim prompt. SDCDB problem areas. ====================== Ok, so what are some of its problems? Lets try to itemize them so we can fix them: * It hangs sometimes when trying to do step or next. This probably has something to do with the context sdcdb tries to build dynamically. Sdcdb tries to trace program operation by placing hidden breakpoints and stepping threw the simulation between these. * Does not print variables properly. Seems to use the wrong address for the variable. (fixed) * ASM listing not implemented. This should be easy enough to add. This feature really needs to be implemented before this is a useful tool. That or addresses of code functions need to be readily available for raw ucSim commands. * No way to browse symbols, files names. Preferably, it is easy to learn the addresses of variables and functions too. (working on this... see new ls,lm,lf commands) * Does not allow listing, setting breakpoints or viewing variables before starting the simulation. (I am fixing now, partly fixed) * p codestr - print on code char * broken, could be CDB info invalid. Changes Made ====================== Added a -z option. Any options after -z on sdcdb invocation line are passed directly to ucSim. Fixed print basic variable command(was not parsing or expecting "0x" in data coming from ucSim). Dump bit command changed from "db" to "dump". Add support for the following alternative ucSim binaries: -mz80 - use "uz80" simulator. -mavr - use "uavr" simulator. -mxa - use "uxa" simulator. Note that Z80(and probably avr/xa) does not produce enough CDB debugging information to make SDCDB useful. Hopefully CDB support will be added to these other linkers and code generators. Added lf,lm,ls commands(list functions, list modules, list symbols). This allows browsing some the CDB information SDCDB pulls in to do the wonderful things it does. Added '.' prefix/command, used alone switches back and forth from ucSim/SDCDB command mode). Also when at the (ucsim) prompt, if a command is prefixed with '.' it will route the command to the SDCDB command processor. (This could obsolete the '!' prefix). ====================== Fix any remaining shortcomings above and make sdcdb integrate better with ucSim. Concerning the hanging on next/step instructions: This is critical to fix. I beleive the problem is related to SDCDB's attempt to dynamically track context. To do this, it sets many temporary break points and uses these to progress step by step through the source code. It does not seem reliable. It might be an idea to offer a simplified mode of stepping and breakpoints. Need to study this more. Make SDCDB integrate better with ucSim. I think if sdcdb can act more transparently in regard to ucSim it would be used more. So stress adding value and enhancing ucSim operation, and not block or hide the functionality of ucSim. * combine print "p" & "pt" together. We have room on the screen, might as well print its type, address and value in one command. * "fr" command prints the current position in the C code. Should also print the raw code address for dumping ucSim code. Developer Notes: ====================== To debug, it might be helpful to turn on verbose debug dumps by uncommenting #define SDCDB_DEBUG in sdcdb.h. Some basic layout: sdcdb.c - main shell of the program. cmd.c - process user commands typed in. simi.c - handle talking to the simulator via a socket connection. symtab.c - Misc. functions to translate and process linked list structures(modules, functions, symbols, etc) and CDB file parsing. break.c - track and implement break points. Understanding the structures and access mechanisms of SDCDB is a bit of work. The structures include generic linked list and function access. These lists are accessed in part by the functions from ../../src/SDCCset.c and SDCChash.c. See the cmd.c:infoSymbols() routine to gain some insight into these main program structures. Or type "info symbols" to dump out some of these. The new ls,lm,lf commands are also based on showing information about these lists of structures. Generic functions are used to act on these linked lists of structures. For example, in cmd.c, DEFSETFUNC(funcWithName) function will find a function structure with a given name. So the linked list of function structures(with the head "functions") is traversed and when one is found with a matching name, a pointer to the function structure is returned. The src/SDCCset.c,SDCCset.h contain much of the core helper routines to allowed to implement these linked list access functions. The dynamic context tracking is difficult to understand. It has some concept of stack use, as in cmd.c:printSymValue(), where it can print variables relative to the stack pointer.