I am trying to convert an unmaintainable user interface driver over to something that uses data structures to define the menu organization (This example is stripped down to the bare minimum from my actual app).
Picture an array of screens, selectable by the user's activation of some arrow keys:
Col 0 Col 1 +-----------+ Row 0 | Screen 1a | +-----------+ /\ || \/ +-----------+ +-----------+ Row 1 | Screen 2a | <===> | Screen 2b | +-----------+ +-----------+
I define a function to output each screen (in the code below, they also change the row & column indices):
void f1a(void) { outputScreen1a(); if(r > 0) r++; return; } /* ============= */ void f2a(void) { outputScreen2a(); if(c < 1) c++; return; } /* ============= */ void f2b(void) { outputScreen2b(); r = c = 0; return; }
These are called by the main() function, using a function pointer table:
static code const void (* code menuFunc[2][2])(void) = { { f1a, NULL }, { f2a, f2b } }; unsigned char r, c; void main(void) { unsigned char i; SFRPAGE = 0; /* Go to default page */ WDTCN = 0xDE; /* Disable watchdog timer */ WDTCN = 0xAD; IE = 0; /* Disable all interrupts */ i = 0; r = c = 0; while (1) { if(i < 70) { i++; } else { i = 0; (*menuFunc[r][c])(); } } /* END while (TRUE) */ } /* END main() */
As presented above, the source file will compile without error. But my application is quite a bit more complex than what I present here, the table is assymetrical (marked by the NULL pointer) and I want to guantee I do not inadvertently dereference it, so I add a qualification to the main control loop:
while (1) { if(i < 70) { i++; } else { i = 0; if((menuFunc[r][c])() != NULL) (*menuFunc[r][c])(); } } /* END while (TRUE) */
C51 does not like this. It flags the statement where I check for NULL:
?????.C:(56): error C193: '!=' : illegal conversion from/to 'void'
NULL is defined in stdio.h:
#define NULL ((void *) 0)
K&R doesn't state it explicitly, but seems to assume that void is an object type, that (void *) can only point to an object, and never uses NULL as a pointer to a function.
So the question is, if I can't use NULL to mark an uncallable function in the table, is there a null function pointer I could use instead?
============================================================ Gary Lynch | To send mail, no$pam in domain name lynchg@no$pam.com | must be changed to stacoenergy. ============================================================
Your line:
if((menuFunc[r][c])() != NULL)
contains a () making it a function call of a function taking void.
You have to realize that the deferencing * is not needed for function pointers.
Try:
if (menuFunc[r][c]) { .... }
to test your pointer.
By George, you've got it! That took care of the problem.
Thanks for the insight.
had you used a static code analyzer, you'd be saying: "By George static code analyzer, you've got it!"
:-)
By 'static code analyzer' I presume you mean PC-Lint, which prompts me to take this to the next level.
I do own a copy of PC-Lint, and have used it in the past to solve some hairy problems. I would like to use it routinely, but am impeded by the tool being apparently an attribute of the project, rather than of uV3 itself.
By that I mean every time I create a new project, I have to go tell the IDE the locations of the lint executable, the configuration file that characterizes my micro, and the compiler's default include files (all things that generally don't change--project to project).
This is about 75% of the effort of installing a new application for EVERY project (and I create a lot of them). So I only go through it if it promises me a major benefit. But I don't run into problems like the one you just witnessed very often (It looks like my last query to this body was last April).
Am I the only one who thinks we ought to be able to just install PC-Lint, enable it in uV3, and be able to run it from then on?
but you can run PC-lint from the command line, or better - using a batch file. Who needs uv3 for that...? just create "lint files" files per project, and you are in business.
lint-nt -w2 -e40 -e10 -e123 -e63 -e19 -e31 -e534 -e409 -e522 -e553 -e537 -e647 -e525 -e539 -e14 -e602 -e547 -e501 -e140 -e526 CO-RV.lnt lint_files.lnt > results.txt
and lint_files.lnt,
-I..\STR9_scheduler -I"\Keil\ARM\INC\ST\91x" -I"\Keil\ARM\RV31\INC" ..\STR9_scheduler\91x_it.c ..\STR9_scheduler\config.c ..\STR9_scheduler\LED.c ..\STR9_scheduler\main.c ..\STR9_scheduler\messaging.c ..\STR9_scheduler\priority_queue.c ..\STR9_scheduler\queue.c ..\STR9_scheduler\scheduler.c ..\STR9_scheduler\Serial.c ..\STR9_scheduler\swi_functions.c ..\STR9_scheduler\synchronization.c ..\STR9_scheduler\system_notifications.c ..\STR9_scheduler\system_services.c ..\STR9_scheduler\timer.c ..\STR9_scheduler\trace_buffer.c
I don't own PC-Lint.
I wrote a little program that extracts a bit of information from the Keil project files (and also looks at the produced output files).
Then I use this to create a Makefile that uses a couple of free compilers to compile (but not link) the source code with suitable warning levels. In my case, it is enough to know what source files are part of the project, and what directories the source is in and what directories to scan for include files.
Not perfect, but a quick way to get a bit of extra static analysis of the code. Spending money on PC-Lint would probably be a better solution, but I did the above once when I was bored and had to wait a couple of hours for a transport. In the end, the solution has produced a couple of intersting warnings that I would have liked support for by the ARM compiler.
Alas, it can't do cross-module analysis, so I should probably some day look at automatic support for any of the free source-code analyzers that are available. When I originally did the above, I didn't had Internet access, so I had to settle for whatever tools/info I had on the laptop.
Anyone who have any special favourites? en.wikipedia.org/.../List_of_tools_for_static_code_analysis
I tried splint yesterday. It is a nice tool, but lacks support for specific compiler extensions besides some GNU stuff.
What I forgot to mention is that I do the above for ARM and not C51 projects. This greatly reduces the problems with compiler extensions.
A bit of creative use of sed or #defines can normally "standardize" the code.
On 24-Oct-2008 05:50; Per Westermark wrote: > > I wrote a little program that extracts a bit of information > from the Keil project files (and also looks at the produced > output files). > > Then I use this to create a Makefile that uses a couple of > free compilers to compile (but not link) the source code > with suitable warning levels. > I keep digressing, but I have been trying to implement just what you describe for years.
I have batch files that call Perl scripts to extract enough info from the *.__i and *.lnp files to create a makefile I could archive with my source. It would need to include the compile- & link-time directives (which I use for configuration management). I can create them for a specific project, but have never gotten one to work as a general purpose utility.
- What language do you write in? - Did you get yours working for the general case?
I really have to check if I used C or C++ ;)
Not the quickest way to write the string manipulation but I didn't have too much tools installed on the laptop, and I got the idea when I failed to buy a book to read while waiting for a plane after the original plane got cancelled.
Yes, it worked quite well, but in this case I wasn't originally so very concerned about compilation options since the goal was to test-compile with other compilers. The important thing was to be able to feed the other compilers with define symbols. My aim was to use the correct set of source files, the correct include directories and the correct conditional compilation options. Then I had to do a bit of automatic tweaking of the source to get it through for example the MinGW version of the gcc compiler.
But yes, it does pick up the command-line options that the ARM compiler prints at the top of the list files, so I can compile the files with the ARM compiler too and with the correct options.
I basically did this instead of doing cross words, without really knowing what would come out of it.
I would like to use it routinely, but am impeded by the tool being apparently an attribute of the project, rather than of uV3 itself.
So what's keeping you from copying and modifying a personally adjusted default project (including Lint settings) instead of creating new ones all the time?
Let's see if I can apply your advice to my logistics.
My 'top level BOM' is a system containing 5 MCUs, which communicate over several networks. Thus I must maintain 5 execution modules and around 120 source files to make a release.
The product is offered in 50 different configurations which I maintain from a common source deck by changing the values of 4 pre-processor constants at build time.
Four of the 5 applications are based on finite state machines, which I implement calling a function pointer table, indexed by the state variable. When elements of the call tree pass strings as parameters to lower-level functions, these strings get stored in the same ?CO? code segment as the function pointer table, and L51 is too dense to realize this is not a recursive function call, bombarding me with a couple dozen warnings and moving all affected functions out of the overlayable RAM logic, which eats up so much internal RAM I have to write OVERLAY directives, unique to each MCU, to get it to fit.
My work is mostly adding new features, and your average feature changes the code in around 2 execution modules. Every other change causes a source file or 2 to grow to the point where I have to re-factor, so my project file source list is NEVER the same between MCUs, and rarely the same between revisions of the same MCU.
So I could possibly create a 'default project file' to copy into each directory, for which I would have to delete all the file entries, the pre-processor constants, and OVERLAY directives, then customize it to the new environment. I had heretofore considered this a wash, but with the wish to enable lint all the time, it is worth running a check.
I'll report back when I know.
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