Make functions of one program available for other programs?

[compu]

When I launch a program via my shell, is it possible to make functions and variables of it available for the launched program?

[ExtendeD]

Sharing functions dynamically would require dynamic libraries, which is not supported and not really planned in Ndless. But these functions can also be exported as a static library, bound with the program launched at compile time (see how libndls is built and used or bwang's C library somewhere on Omnimaga).

Sharing variables would require a Shared memory, I don't know if the TI-Nspire includes anything like this. A dirty workaround would be to pass the address of a memory block allocated by the shell to the programs launched as a command line parameter, and access the variables relatively to this base address. This could also be used to call back dynamically functions from the shell by the way.

[compu]

I've tried it on this way now:

I define a structre called _rshellAPI (in a header file that is included in rshell and the launched program) which looks like this:

Code: Select All | Copy To Clipboard

1 2 3 4 5 6 7 8 9 10 11 12 13

typedef struct _rshellAPI { void (*c_draw)(void); void (*c_clear)(void); void (*c_writec)(char ch); void (*c_write)(char* str); void (*c_swrite)(char* format, int buflen, ...); char (*cn_readc)(void); char (*c_readc)(void); int (*c_read)(char* str); } rshellAPI;

In rshell's source, I initialize this structure with functions of Nspire I/O:

Code: Select All | Copy To Clipboard

1 2 3 4 5 6 7 8 9 10 11

rshellAPI rshell = { &c_draw, &c_clear, &c_writec, &c_write, &c_swrite, &cn_readc, &c_readc, &c_read };

And then pass it to the launched program:

Code: Select All | Copy To Clipboard

1	((void (*)(int, char **, rshellAPI*))(docptr + sizeof(PRGMSIG)))(n_argc, n_argv, &rshell);

Then I've changed the launched program to use these functions:

Code: Select All | Copy To Clipboard

1	int main(int argc, char** argv, rshellAPI* rshell)

Code: Select All | Copy To Clipboard

1	rshell->c_writec('\n');

All this compiles without errors, but when the launched program tries to call one of the functions, this happens:

Code: Select All | Copy To Clipboard

1 2 3 4 5

Error at PC=11140B6C: Unaligned read_word: 11         Backtrace: Frame     PrvFrame Self     Return   Start 11136665: 41000000 3A41003A 003E7325 000A0D20 41000000: invalid address

What is wrong with this?

[ExtendeD]

Does it crash before the call or within the function called?

[bsl]

Try isolating the problem, see if what you passed is getting there.
They should match.

from the launcner:
printf("n_argc=%i, n_argc=%p, &rshell=%X\n",n_argc, n_argv, &rshell);
((void (*)(int, char **, rshellAPI*))(docptr + sizeof(PRGMSIG)))(n_argc, n_argv, &rshell);


from the launcned:
int main(int argc, char** argv, rshellAPI* rshell){
 printf(argc=%i, argv=%p, rshell=%p\n",argc, argv, rshell);
.
.
.
}

Alignment errors: The adressess in argv, rshell should end in: 0,4,8,C


Declaring with "static" might solve the alignment problem:
static rshellAPI rshell =
{
   &c_draw,
   &c_clear,
   &c_writec,
   &c_write,
   &c_swrite,
   &cn_readc,
   &c_readc,
   &c_read
};

[calc84maniac]

Do function pointers work properly in the Ndless toolchain? I remember they didn't at some point. What are the GCC options in your makefile?

[bsl]

Yes, they do.
Look at  ploaderhook.c

[ExtendeD]

Do function pointers work properly in the Ndless toolchain? I remember they didn't at some point. What are the GCC options in your makefile?

Wait, you're right, I forgot that one: http://hackspire.unsads.com/wiki/index.php/Ndless_features_and_limitations#Global_variables
You should use nl_relocdata() on your functions array.

[compu]

First of all, thanks for your help.
Currently I'm not at home, but how do I have to call nl_relocdata() with a structure?
What is the first argument (nl_relocdata_data on Hackspire)?

[compu]

BUMP

Code: Select All | Copy To Clipboard

1	n_argc=1, n_argv=1800e070, &rshell=111B0400

Code: Select All | Copy To Clipboard

1	argc=1, argv=1800e070, rshell=00000001

[bsl]

Try this:
Instead of passing a third argument, just use the last n_argv[19]
to pass the rshell address.
Launcher

Code: Select All | Copy To Clipboard

1 2	n_argv[19] = (char*)&rshell; // put pointer in last array slot

Launched

Code: Select All | Copy To Clipboard

1 2 3 4 5 6 7 8

int main(int argc, char** argv){  rshellAPI *rshell;   rshell = (rshellAPI *)argv[19]; . . . }

[compu]

Doesn't work, but at least the address of rshell in the launched program isn't 00000001 anymore 

I got 2 different errors and one time it just restarted.

Code: Select All | Copy To Clipboard

1 2	Launcher: 1800e93c Launched: 111793a8

[ExtendeD]

First of all, thanks for your help.
Currently I'm not at home, but how do I have to call nl_relocdata() with a structure?
What is the first argument (nl_relocdata_data on Hackspire)?

There was a typo in the sample on Hackspire, it's fixed: http://hackspire.unsads.com/wiki/index.php/Ndless_features_and_limitations#Global_variables
The first argument would be rshell in your case.