Hello hugo,

On Apr 20 19:04 96, hugo landsman of 2:283/608.5 wrote:

 MS>> how do you kill this thread? 

 hl> ungetc(27,stdin)?

:-), but not really? or?

first i will you the expected problems and then i will prove them:

a) the code for getch() MAY look like (and in fact the MS-C 6.0 getch()
code looks exactly this way. i looked into the ms-c lib)

  getch()
  {
   if (ungetChar!=-1) return ungetCharArray[ungetChar--];
   KbdCharIn(...,WAIT);
  }

 so, when thread 2 starts a getch, there is no unget char pending and getch
calls KbdCharIN and waits until a key is pressed...

 when thread1 performs the unget, the following code is executed:

  unget(char x)
  {
   if (spaceFree in ungetCharArray)
     {
      ungetCharArray[++ungetChar]=x;
      return
     }
  }

 b) another compiler vendor (VACPP) has similar code, but has made the code
thread-safe:

 there is 1 Mutex-semaphore for the Kbd/Vio code. 

  getch()
  {
   requestLock(mux)
   ...
  }

  ungetch()
  {
   requestLock(mux)
   ...
  }

 so, in this case, thread2 is waiting for getch and thread1 has no chance
in ungetch a char...

ok, here's a sample app :


#define INCL_DOSSEMAPHORES
#define INCL_DOSPROCESS
#include 

#include 
#include 
#include 

#define THREADSTACK     65536

//--------------------------------------------------------------------------
static void _Optlink input1(void *dummy)
{
 printf("####### 1\n");
 getch();
 printf("####### 2\n");
}
//--------------------------------------------------------------------------
int main(int argc, char *argv[], char *envp[])
{
 TID tid = (TID)_beginthread(input1,0, THREADSTACK, 0);

 printf("----1------\n");
 DosSleep(5000);

 printf("----2------\n");
 ungetch('a');
 printf("----3------\n");
 DosWaitThread(&tid, DCWW_WAIT);
 printf("----4------\n");
}

icc -Fd+ -Sm -Ss+ -Si+ -Tl30 -Q+ -Wall+cls-gnr-lan-par-ppt-vft-inl-ppc-use-
-W3 -Gm+ xxx1.cpp

PS: to terminate the hanging app just press a key ....
 WARPED!, Mario

--- Msgedsq/2 2.2e