Styjun

I am developing a code in which I access the values from one function (func1) into another function (func2). Both functions have pointers as argument. I am calling "func2" in an other file to pass the values further for writing over UART.

Below is code snippet:

func1: (file one.c)

int16_t driver485Compare(uint8_t * message, uint16_t len)

 int j = 0;
 uint8_t FWmsg[9] = 0x09,0x30,0x30,0x32,0x32,0x31,0x31,0x30,0x36; 
 uint8_t adata[9] = 0x09,0x30,0x30,0x30,0x30,0x30,0x30,0x30,0x30; 

 printf("compare command.........."); 
 for (j=0; j<9; j++)
 
 adata[j] = message[j] ;
 printf("%d ",adata[j]);
 

 if(compareArray(FWmsg,adata,7)==0)
 
 uint8_t add, fwcommand, fwaction;
 uint16_t fwvalue;
 GetABFWversion(&message, &add, &fwcommand, &fwaction, &fwvalue);

 printf("elements matched n");
 // HERE I NEED TO read VALUES OF add, fwcommand, fwaction, fwvalue and pass to "message"

 

 else
 
 printf("Arrays have different elements.n");
 

 return 0;

func2: (file two.c)

int8_t GetABFWversion(uint8_t* add, uint8_t* fwcommand, uint8_t* fwaction, uint16_t* fwvalue) 
 
 char MyCopy[10]; 
 strcpy (MyCopy, FIRMWARE_VERSION);
 char MyCopy1[10];
 for (int k=0; k<9; k++)
 
 int l=1;
 MyCopy1[k] = MyCopy[k+l]; 
 

 char FWversion_AB[10] = 0;
 for(int x=6;x<9;x++)
 
 FWversion_AB[z] = MyCopy1[x];
 z++;
 

 uint16_t val = atoi(FWversion_AB);
 *add = RS485_ADDRESS; //values read from enum
 *fwcommand = CMD_GET_VERSION_AB; //values read from enum
 *fwaction = CMD_ACTION_AB; //values read from enum
 *fwvalue = val;

// NEED TO PASS VALUES OF add, fwcommand, fwaction, fwval to "driver485Compare()"

func3: (in different file (three.c))

void TaskSlave(void *p_arg) //b - communication Task

 uint8_t res; 
 rs485_message_t rs485Msg;

 (void)p_arg;
 while(1)
 
 res = driver485Read((uint8_t *)&rs485Msg, RS485_MSG_LENGTH); 

 res = driver485Compare((uint8_t *)&rs485Msg, RS485_MSG_LENGTH); 
 //add, fwcommad, fwaction, fwval SHOULD BE REFLECTED HERE WHILE CALLING "driver485Compare()" IN ABOVE STATEMENT.

 

What is not working? All functions in C have extern applied by default, so there is no reason you can't call a function declared in one source from another. You simply have to provide a function prototype, e.g. int fn_in_other_file (params); for the function in the file where you want to use it before you actually use it. Just as you do when using a function within the same source file.

The linker will resolve all symbol names when linking the object files together despite the functions being defined in separate source files. There is nothing special you need to do there.

Take a very basic example of 3 files where the function from one file are called in another:

File 1 (a.c)

int funA (void)

 return 2;

File 2 (b.c) calling funA()

int funA (void); /* function prototype for funA() in file where it is used */

int funB (void)

 return funA() + 3;

(note: how the prototype for funA() is included at the beginning of b.c before funA() is called. (something normally done with header files) You can write the prototype as extern int funA (void); to be explicit, but there is no need, the extern keyword is implied.)

File 3 (main.c) calling funB()

#include <stdio.h>

int funB(void); /* function prototype for funB() in file where it is used */

int main (void) 

 printf ("funB() : %dn", funB());

Looking at the flow you can deduce that the output from main() should be "funB() : 5", so compile all three and check:

$ gcc -Wall -Wextra -pedantic-std=gnu11 -O2 a.c b.c -o bin/main main.c

And the expected output is:

$ ./bin/main
funB() : 5

This is the very same circumstance that you face in your question and you can apply it to solve your problem. Give it a try and let me know if you have further questions.