At 12:03 12/29/98 -0700, Dwayne Reid wrote:
>The only implementations of circular buffers
>that I've seen do NOT overwrite the old values when popping - the pointers
>change but the old values remain.  This is different from the pic stack
>behaviour.

actually all circular implementations i know do overwrite (that's why they
are circular) -- of course not when popping, but when pushing. how about

char stack[N];
char *p = stack;

void push(char c) {
  *p++ = c; // normal push
  if (p >= stack+N) p=stack; // make it circular
}

char pop(void) {
  if (--p < stack) p=stack+N-1;
  return *p;
}

ge