Omnimaga
Calculator Community => TI Calculators => Calculator C => Topic started by: compu on August 22, 2011, 03:56:41 pm
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When I launch a program via my shell (http://ourl.ca/12605), is it possible to make functions and variables of it available for the launched program?
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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.
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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:
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 (http://nspforge.unsads.com/p/nspireio):
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:
((void (*)(int, char **, rshellAPI*))(docptr + sizeof(PRGMSIG)))(n_argc, n_argv, &rshell);
Then I've changed the launched program to use these functions:
int main(int argc, char** argv, rshellAPI* rshell)
rshell->c_writec('\n');
All this compiles without errors, but when the launched program tries to call one of the functions, this happens:
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?
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Does it crash before the call or within the function called?
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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
};
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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?
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Yes, they do.
Look at ploaderhook.c
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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.
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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)?
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BUMP
n_argc=1, n_argv=1800e070, &rshell=111B0400argc=1, argv=1800e070, rshell=00000001
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Try this:
Instead of passing a third argument, just use the last n_argv[19]
to pass the rshell address.
Launcher
n_argv[19] = (char*)&rshell; // put pointer in last array slot
Launched
int main(int argc, char** argv){
rshellAPI *rshell;
rshell = (rshellAPI *)argv[19];
.
.
.
}
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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.
Launcher: 1800e93c
Launched: 111793a8
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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.