Unfortunately, this isn't the case - things like polymorphism and other properties of C++ lead to loads of "Undefined reference" errors when trying to access C functions from C++ code and vice versa.

The solution consist of special extern directives - the two sites below should keep you covered:
Mixing C and C++ code in the same program
How to mix C and C++

Good luck porting!

As I stumbled across a few interesting things, I felt like sharing the code below:

#if defined MOBIHAND
WBM_OpenWebPage(0,"https://www.mobihand.com/mobilecart/mc1.asp?posid=162&pid=8703");
#elif defined PALMGEAR
WBM_OpenWebPage(0,"http://www.palmgear.com/index.cfm?fuseaction=sc.buy&prodid=137239&buytoken=62745661");
#else
#error "no ESD Specified"
#endif


The first thing that I considered interesting is the #error macro – it allows you to stop the compilation process if some condition is not met. In the example above, the condition would be that no ESD flag is set. Furthermore, nesting definitions isn’t too easy either – the syntax involves the defined operator (which the PODS does NOT highlight).

The folks there currently discuss the various encryption options available to Palm OS developers – if your apps need a security improvement, click the link below to get to the first post:
Data encryption Palm OS

The simulator gave an alert along the lines of “Invalid insertion point” – WTF?

The alert text above is a classic example for a completely unrelated error message – the reason for the alert is simple: the text field FldShadow is not high enough for the text it should contain. Just increase the height of the field – and the fatal alert is gone for good!

Simple DirectMedia Layer (SDL) is a cross-platform, multimedia, free software library written in C that creates an abstraction over various platforms’ graphics, sound, and input APIs, allowing a developer to write a computer game or other multimedia application once and run it on many operating systems including Linux, Windows, Mac OS X, AmigaOS and its clone MorphOS. It manages video, events, digital audio, CD-ROM, sound, threads, shared object loading, networking and timers.

Now, an user called TomB has opened a thread on Nexave, announcing that he is working on porting this very library to Palm OS. Here is a translation of his german post:

Dear Ladies and Gentlemen,

I have posted a first version of my port right here: https://sourceforge.net/project/showfiles.php?group_id=212180. I have included a few t5est programs and games that run well on a Treo 650 and a Zodiac – a Tungsten E has had issues due to low RAM.

I would be very thankful for testers!
For developers: I support all except OpenGL, CDRom and Threads. The libraries SDL_mixer, SDL_image and spritelib are included. Additionally, ARM versions of most standard C library calls are included as a bonus!

Should anyone of you feel like testing the SDL port for Palm OS, please leave a comment with your experiences here. Alexander Gratz and I will then post the URL of this post to Nexave in order to allow TomB to participate in the discussion!

This version of ZLPlugin.h has worked well for me with OnBoardC 2.4 and 2.6 – it allows you to use all ZLauncher functions except for ZLDrawChars(no idea why, but it kills the compile process). Additionally, the current build of ZLauncher seems to have a bug in the variable-length preference functions…the calls execute correctly, but don’t work(aka save/read data).

Anyways, here goes:
ZLPlugin.h.pdb

Anyways, the input is in traditional degrees, and the output is a float value. If you are short on memory, you could also transform the input to the sine table to get cosine or vice versa…although this IMHO doesn’t pay out(a simple lookup is faster)…

Enjoy!

P.s. Non-coders…Sorry for the long post…

float cosine[]={1,
0.999847695,
0.999390827,
0.998629535,
0.99756405,
0.996194698,
0.994521895,
0.992546152,
0.990268069,
0.987688341,
0.984807753,
0.981627183,
0.978147601,
0.974370065,
0.970295726,
0.965925826,
0.961261696,
0.956304756,
0.951056516,
0.945518576,
0.939692621,
0.933580426,
0.927183855,
0.920504853,
0.913545458,
0.906307787,
0.898794046,
0.891006524,
0.882947593,
0.874619707,
0.866025404,
0.857167301,
0.848048096,
0.838670568,
0.829037573,
0.819152044,
0.809016994,
0.79863551,
0.788010754,
0.777145961,
0.766044443,
0.75470958,
0.743144825,
0.731353702,
0.7193398,
0.707106781,
0.69465837,
0.68199836,
0.669130606,
0.656059029,
0.64278761,
0.629320391,
0.615661475,
0.601815023,
0.587785252,
0.573576436,
0.559192903,
0.544639035,
0.529919264,
0.515038075,
0.5,
0.48480962,
0.469471563,
0.4539905,
0.438371147,
0.422618262,
0.406736643,
0.390731128,
0.374606593,
0.35836795,
0.342020143,
0.325568154,
0.309016994,
0.292371705,
0.275637356,
0.258819045,
0.241921896,
0.224951054,
0.207911691,
0.190808995,
0.173648178,
0.156434465,
0.139173101,
0.121869343,
0.104528463,
0.087155743,
0.069756474,
0.052335956,
0.034899497,
0.017452406,
2.832769449E-16,
-0.017452406,
-0.034899497,
-0.052335956,
-0.069756474,
-0.087155743,
-0.104528463,
-0.121869343,
-0.139173101,
-0.156434465,
-0.173648178,
-0.190808995,
-0.207911691,
-0.224951054,
-0.241921896,
-0.258819045,
-0.275637356,
-0.292371705,
-0.309016994,
-0.325568154,
-0.342020143,
-0.35836795,
-0.374606593,
-0.390731128,
-0.406736643,
-0.422618262,
-0.438371147,
-0.4539905,
-0.469471563,
-0.48480962,
-0.5,
-0.515038075,
-0.529919264,
-0.544639035,
-0.559192903,
-0.573576436,
-0.587785252,
-0.601815023,
-0.615661475,
-0.629320391,
-0.64278761,
-0.656059029,
-0.669130606,
-0.68199836,
-0.69465837,
-0.707106781,
-0.7193398,
-0.731353702,
-0.743144825,
-0.75470958,
-0.766044443,
-0.777145961,
-0.788010754,
-0.79863551,
-0.809016994,
-0.819152044,
-0.829037573,
-0.838670568,
-0.848048096,
-0.857167301,
-0.866025404,
-0.874619707,
-0.882947593,
-0.891006524,
-0.898794046,
-0.906307787,
-0.913545458,
-0.920504853,
-0.927183855,
-0.933580426,
-0.939692621,
-0.945518576,
-0.951056516,
-0.956304756,
-0.961261696,
-0.965925826,
-0.970295726,
-0.974370065,
-0.978147601,
-0.981627183,
-0.984807753,
-0.987688341,
-0.990268069,
-0.992546152,
-0.994521895,
-0.996194698,
-0.99756405,
-0.998629535,
-0.999390827,
-0.999847695,
-1,-0.999847695,
-0.999390827,
-0.998629535,
-0.99756405,
-0.996194698,
-0.994521895,
-0.992546152,
-0.990268069,
-0.987688341,
-0.984807753,
-0.981627183,
-0.978147601,
-0.974370065,
-0.970295726,
-0.965925826,
-0.961261696,
-0.956304756,
-0.951056516,
-0.945518576,
-0.939692621,
-0.933580426,
-0.927183855,
-0.920504853,
-0.913545458,
-0.906307787,
-0.898794046,
-0.891006524,
-0.882947593,
-0.874619707,
-0.866025404,
-0.857167301,
-0.848048096,
-0.838670568,
-0.829037573,
-0.819152044,
-0.809016994,
-0.79863551,
-0.788010754,
-0.777145961,
-0.766044443,
-0.75470958,
-0.743144825,
-0.731353702,
-0.7193398,
-0.707106781,
-0.69465837,
-0.68199836,
-0.669130606,
-0.656059029,
-0.64278761,
-0.629320391,
-0.615661475,
-0.601815023,
-0.587785252,
-0.573576436,
-0.559192903,
-0.544639035,
-0.529919264,
-0.515038075,
-0.5,
-0.48480962,
-0.469471563,
-0.4539905,
-0.438371147,
-0.422618262,
-0.406736643,
-0.390731128,
-0.374606593,
-0.35836795,
-0.342020143,
-0.325568154,
-0.309016994,
-0.292371705,
-0.275637356,
-0.258819045,
-0.241921896,
-0.224951054,
-0.207911691,
-0.190808995,
-0.173648178,
-0.156434465,
-0.139173101,
-0.121869343,
-0.104528463,
-0.087155743,
-0.069756474,
-0.052335956,
-0.034899497,
-0.017452406,
-1.07187544E-15,
0.017452406,
0.034899497,
0.052335956,
0.069756474,
0.087155743,
0.104528463,
0.121869343,
0.139173101,
0.156434465,
0.173648178,
0.190808995,
0.207911691,
0.224951054,
0.241921896,
0.258819045,
0.275637356,
0.292371705,
0.309016994,
0.325568154,
0.342020143,
0.35836795,
0.374606593,
0.390731128,
0.406736643,
0.422618262,
0.438371147,
0.4539905,
0.469471563,
0.48480962,
0.5,
0.515038075,
0.529919264,
0.544639035,
0.559192903,
0.573576436,
0.587785252,
0.601815023,
0.615661475,
0.629320391,
0.64278761,
0.656059029,
0.669130606,
0.68199836,
0.69465837,
0.707106781,
0.7193398,
0.731353702,
0.743144825,
0.75470958,
0.766044443,
0.777145961,
0.788010754,
0.79863551,
0.809016994,
0.819152044,
0.829037573,
0.838670568,
0.848048096,
0.857167301,
0.866025404,
0.874619707,
0.882947593,
0.891006524,
0.898794046,
0.906307787,
0.913545458,
0.920504853,
0.927183855,
0.933580426,
0.939692621,
0.945518576,
0.951056516,
0.956304756,
0.961261696,
0.965925826,
0.970295726,
0.974370065,
0.978147601,
0.981627183,
0.984807753,
0.987688341,
0.990268069,
0.992546152,
0.994521895,
0.996194698,
0.99756405,
0.998629535,
0.999390827,
0.999847695,
1};

float sine[]=
{0,
0.017452406,
0.034899497,
0.052335956,
0.069756474,
0.087155743,
0.104528463,
0.121869343,
0.139173101,
0.156434465,
0.173648178,
0.190808995,
0.207911691,
0.224951054,
0.241921896,
0.258819045,
0.275637356,
0.292371705,
0.309016994,
0.325568154,
0.342020143,
0.35836795,
0.374606593,
0.390731128,
0.406736643,
0.422618262,
0.438371147,
0.4539905,
0.469471563,
0.48480962,
0.5,
0.515038075,
0.529919264,
0.544639035,
0.559192903,
0.573576436,
0.587785252,
0.601815023,
0.615661475,
0.629320391,
0.64278761,
0.656059029,
0.669130606,
0.68199836,
0.69465837,
0.707106781,
0.7193398,
0.731353702,
0.743144825,
0.75470958,
0.766044443,
0.777145961,
0.788010754,
0.79863551,
0.809016994,
0.819152044,
0.829037573,
0.838670568,
0.848048096,
0.857167301,
0.866025404,
0.874619707,
0.882947593,
0.891006524,
0.898794046,
0.906307787,
0.913545458,
0.920504853,
0.927183855,
0.933580426,
0.939692621,
0.945518576,
0.951056516,
0.956304756,
0.961261696,
0.965925826,
0.970295726,
0.974370065,
0.978147601,
0.981627183,
0.984807753,
0.987688341,
0.990268069,
0.992546152,
0.994521895,
0.996194698,
0.99756405,
0.998629535,
0.999390827,
0.999847695,
1,
0.999847695,
0.999390827,
0.998629535,
0.99756405,
0.996194698,
0.994521895,
0.992546152,
0.990268069,
0.987688341,
0.984807753,
0.981627183,
0.978147601,
0.974370065,
0.970295726,
0.965925826,
0.961261696,
0.956304756,
0.951056516,
0.945518576,
0.939692621,
0.933580426,
0.927183855,
0.920504853,
0.913545458,
0.906307787,
0.898794046,
0.891006524,
0.882947593,
0.874619707,
0.866025404,
0.857167301,
0.848048096,
0.838670568,
0.829037573,
0.819152044,
0.809016994,
0.79863551,
0.788010754,
0.777145961,
0.766044443,
0.75470958,
0.743144825,
0.731353702,
0.7193398,
0.707106781,
0.69465837,
0.68199836,
0.669130606,
0.656059029,
0.64278761,
0.629320391,
0.615661475,
0.601815023,
0.587785252,
0.573576436,
0.559192903,
0.544639035,
0.529919264,
0.515038075,
0.5,
0.48480962,
0.469471563,
0.4539905,
0.438371147,
0.422618262,
0.406736643,
0.390731128,
0.374606593,
0.35836795,
0.342020143,
0.325568154,
0.309016994,
0.292371705,
0.275637356,
0.258819045,
0.241921896,
0.224951054,
0.207911691,
0.190808995,
0.173648178,
0.156434465,
0.139173101,
0.121869343,
0.104528463,
0.087155743,
0.069756474,
0.052335956,
0.034899497,
0.017452406,
5.665538898E-16,
-0.017452406,
-0.034899497,
-0.052335956,
-0.069756474,
-0.087155743,
-0.104528463,
-0.121869343,
-0.139173101,
-0.156434465,
-0.173648178,
-0.190808995,
-0.207911691,
-0.224951054,
-0.241921896,
-0.258819045,
-0.275637356,
-0.292371705,
-0.309016994,
-0.325568154,
-0.342020143,
-0.35836795,
-0.374606593,
-0.390731128,
-0.406736643,
-0.422618262,
-0.438371147,
-0.4539905,
-0.469471563,
-0.48480962,
-0.5,
-0.515038075,
-0.529919264,
-0.544639035,
-0.559192903,
-0.573576436,
-0.587785252,
-0.601815023,
-0.615661475,
-0.629320391,
-0.64278761,
-0.656059029,
-0.669130606,
-0.68199836,
-0.69465837,
-0.707106781,
-0.7193398,
-0.731353702,
-0.743144825,
-0.75470958,
-0.766044443,
-0.777145961,
-0.788010754,
-0.79863551,
-0.809016994,
-0.819152044,
-0.829037573,
-0.838670568,
-0.848048096,
-0.857167301,
-0.866025404,
-0.874619707,
-0.882947593,
-0.891006524,
-0.898794046,
-0.906307787,
-0.913545458,
-0.920504853,
-0.927183855,
-0.933580426,
-0.939692621,
-0.945518576,
-0.951056516,
-0.956304756,
-0.961261696,
-0.965925826,
-0.970295726,
-0.974370065,
-0.978147601,
-0.981627183,
-0.984807753,
-0.987688341,
-0.990268069,
-0.992546152,
-0.994521895,
-0.996194698,
-0.99756405,
-0.998629535,
-0.999390827,
-0.999847695,
-1,
-0.999847695,
-0.999390827,
-0.998629535,
-0.99756405,
-0.996194698,
-0.994521895,
-0.992546152,
-0.990268069,
-0.987688341,
-0.984807753,
-0.981627183,
-0.978147601,
-0.974370065,
-0.970295726,
-0.965925826,
-0.961261696,
-0.956304756,
-0.951056516,
-0.945518576,
-0.939692621,
-0.933580426,
-0.927183855,
-0.920504853,
-0.913545458,
-0.906307787,
-0.898794046,
-0.891006524,
-0.882947593,
-0.874619707,
-0.866025404,
-0.857167301,
-0.848048096,
-0.838670568,
-0.829037573,
-0.819152044,
-0.809016994,
-0.79863551,
-0.788010754,
-0.777145961,
-0.766044443,
-0.75470958,
-0.743144825,
-0.731353702,
-0.7193398,
-0.707106781,
-0.69465837,
-0.68199836,
-0.669130606,
-0.656059029,
-0.64278761,
-0.629320391,
-0.615661475,
-0.601815023,
-0.587785252,
-0.573576436,
-0.559192903,
-0.544639035,
-0.529919264,
-0.515038075,
-0.5,
-0.48480962,
-0.469471563,
-0.4539905,
-0.438371147,
-0.422618262,
-0.406736643,
-0.390731128,
-0.374606593,
-0.35836795,
-0.342020143,
-0.325568154,
-0.309016994,
-0.292371705,
-0.275637356,
-0.258819045,
-0.241921896,
-0.224951054,
-0.207911691,
-0.190808995,
-0.173648178,
-0.156434465,
-0.139173101,
-0.121869343,
-0.104528463,
-0.087155743,
-0.069756474,
-0.052335956,
-0.034899497,
-0.017452406,
-1.13310778E-15};

However, the API’s Palm itself provides do not work on any shipping Treo. I myself have tested the MiniCamera sample from the SDK on a Palm Treo 650 and a Treo 680 and can report that changing brightness and contrast of images(!!!) via CamLibControl works on neither. A comrade from 1src has tested MiniCamera on a Treo 755p(latest Palm device) and doesn’t report any successes either.

So, to cut a long story short, you can NOT programatically change image brightness/contrast on a Palm OS Treo. You need to live with what the camera manager provides…so much for the Treo being a high-tech smartphone. As for the MiniCamera API sample … do not ask me why it is in there if it doesn’t work …

P.s. Sorry for the aggressive tune…but please, Palm, come on. I mean, every 100€ dumb phone can do that!

1. Define your application creator
#define DACREATOR 'myDA'

2. Define a the name of your feature ID giving it a unique number. To make it real easy, give it a name reminding of the global which pointer it will contain. I put an “f” in front of it.
#define fBuffer 1

3. For ease of use, put in the following two functions already published on TamsPalm:
//------------------------------------
MemPtr malloc(UInt16 size) {
MemHandle h = MemHandleNew(size);
if (!h) {
return NULL;
}
return (MemPtr) MemHandleLock(h);
}

//------------------------------------
void free(MemPtr ptr) {
MemHandle h = MemPtrRecoverHandle(ptr);
if(!h) return;
MemHandleUnlock(h);
MemHandleFree(h);
ptr = NULL;
}

4. Put in two functions that will make it easy to set and get the App Defined Feature which will contain the pointers to the globals.
// ------------------------------------
UInt32 GetFtr(UInt16 ftrID){
UInt32 test=0;
Err e=FtrGet(DACREATOR, ftrID, &test);
if (e!=0){
FtrSet(DACREATOR, ftrID, 0);
test=0;
}
return test;
}

// ------------------------------------
void SetFtr(UInt16 ftrID, UInt32 val){
FtrSet(DACREATOR, ftrID, val);
}

5. Declare your global variable and place them in the Dynamic Heap. To use the Dynamic Heap is really cool. You can almost put as much as you like up there without affecting the stack which has a limited space already used by the app running when the DA is launched.
char *Buffer=malloc(32000);

6. Set the pointer as a feature value.
SetFtr(fBuffer, (UInt32)Buffer);

7. To access the global variable in your functions, you need to get the pointer to it. That is done like this:
char *Buffer=GetFtr(fBuffer);
StrCopy(Buffer,"Hello!");

or even use it directly as in this example:
StrCopy((char *)GetFtr(fBuffer),"Hello!");

8. When quitting the DA, you need to free the global variable. Don’t forget it! It’s more important for a DA than for normal app. Quitting a normal app releases the variables but quitting a DA does not.
free((char *)GetFtr(fBuffer));

That’s it. It’s easy, fast, powerful, and safe. It also works with structures, so you can easily have your DAappPrefs available in all functions. If you want to see how it works in a real DA, have a look at the thumbboardDA code.

To cut a long story short, the CERT has posted a list of common C gotchas there. No, not the kind of gotchas you can find in a beginner’s book…but real gotchas from everyday development/porting work.

Take a look by all means…and plucker it if you feel like it!