program compile help

Hi all..

I'm trying to use someone else's design for a project i'm working on but have to compile some code that is pretty short but will not compile.

it is a program to load a video data stream file to memory and then send it to the parallel port uninterrupted using a pc in dos, data flow is controlled by the ACK input on the parallel port from an external CPLD.

here is the code...

Code:

---

/*********************************************

  READ_PSK.C 

  READING  SOFTWARE FOR .PSK  FILES

  May 16th 2004

  (C) 2004  J.F. FOURCADIER  F4DAY

*************************************************/

#include <stdio.h>
#include <conio.h>
#include <dos.h>
#include <stdlib.h>

int main (void)
{
      char nomfich[51];
      FILE *data_file;
      int base = 0x78C0; // output port address
      int data_reg = base + 0;
      int status_reg = base + 1;
      unsigned char *buf;
      unsigned long n;
      int k = 0;       
      // FILE SIZE
      // DATV_0 =  283968L
      // DATV_1 = 7497408L
      // DATV_3 = 1060800L
      long filesize = 7497408L; // file size
      buf = malloc(filesize);
      clrscr();

      data_file = fopen("C:\\DJGPP\\MYPRO\\datv_1.psk","rb");
      if (data_file == 0)
            {
                printf("fopen failed\n");
                printf("\n\nname of file should be datv_x.psk  !\n");
                exit(1);
            }
      else
      {
      printf("\nreading.....");
      }
      fread(buf,1,filesize,data_file);
      fclose(data_file);

      disable();
      printf("\ntransmitting.....");
      n = 0;
      do
      {
      do
          {
          outportb(data_reg,*(buf+n));
          // wait for next state on nAck :
          do { } while (((inportb(status_reg)) | 0xBF) != 0xFF);
          n++;
          outportb(data_reg,*(buf+n));
          // wait for next state on nAck :
          do { } while (((inportb(status_reg)) | 0xBF) == 0xFF);
          n++;
          }
      while(n <= (filesize - 1));
      n=0;
      k++;
      }
      while(!0);        // endless loop
//    while(k<500);

      free(buf);
      enable();
     
      exit(0);
}

---

So the problem is when i try to compile i get this error for this line:
>>>>buf = malloc(filesize)

Error: Invalid conversion from 'void*' to 'unsigned char*'

Compiler i'm using is DJGPP with c and c++ parts installed.


i havent a clue really about pointers etc so i'm not sure what is wrong.....
can anyone help?

thanks

Rob

Do you seriously have anything against writing modern programs? Port this over to something realistic.

Anyway, your actual problem here is possibly that you have to cast malloc() on this ancient compiler.

Code:

---

buf = (unsigned char *)malloc(filesize);

---

The design i'm buiding from is not my own and i can only just about do the basics in C so this will have to do for now, it is supposed to rely on dos to be able to work fast enough aparrently, but what do i know...ha

will give your idea a try..

thanks

Rob

If it requires casting, then it must be compiled as C++, since C doesn't require casting... So, this is supposed to be done in C? Then why is the library compiled as C++?

> Error: Invalid conversion from 'void*' to 'unsigned char*'
This usually means you're compiling your C program with a C++ compiler.
Try
gcc prog.c
rather than
gxx prog.cpp

And what does "uninterrupted" mean?

Quote:

---

Originally Posted by Salem

> Error: Invalid conversion from 'void*' to 'unsigned char*'
This usually means you're compiling your C program with a C++ compiler.
Try
gcc prog.c
rather than
gxx prog.cpp

And what does "uninterrupted" mean?

---

As far as i can tell it disables all other activities like keyboard input etc to reduce any chance of data flow 'glitches'.
I think the loading to memory is meant to reduce the chance for delays compared with sending the file direct from the disk.

Anyway i did add the casting as above and it coompiled first time.. now to test!

Like i said i haven't much idea about programming.
This is a relatively small part of the project (a digital television transmitter for ham radio), the hardware was the main task so i don't want to spend much time here until it can actually get the whole thing working in a fashion!

Rob