New NOTIFY system call! Queued at kernel. Duplicate messages (with same source

and type) are overwritten with newer flags/ arguments. The interface from
within the kernel is lock_notify(). User processes can make a system call with
notify(). NOTIFY fully replaces the old notification mechanism.

kernel/misc.c

@@ -2,6 +2,9 @@
  *   panic	    abort MINIX due to a fatal error
  *   bad_assertion  for debugging
  *   bad_compare    for debugging
+ *   alloc_bit      bit map manipulation
+ *   free_bit       bit map manipulation
+ *   print_bitmap   bit map manipulation
  */
 
 #include "kernel.h"
@@ -35,6 +38,78 @@ int n;
 }
 
 
+/*===========================================================================*
+ *			   print_bitmap					     * 
+ *===========================================================================*/
+PUBLIC void print_bitmap(bitmap, nr_bits)
+bitchunk_t *bitmap; 
+bit_t nr_bits;
+{
+    bit_t bit_i;
+    
+    for (bit_i=0; bit_i < nr_bits; bit_i++) {
+
+        kprintf("%d", GET_BIT(bitmap, bit_i) > 0 );
+        if (! ((bit_i+1) % 8) )   kprintf(" ", NO_ARG);
+        if (! ((bit_i+1) % 64) )   kprintf("\n", NO_ARG);
+    }
+    kprintf("\n", NO_ARG);
+}
+
+/*===========================================================================*
+ *			   	free_bit				     * 
+ *===========================================================================*/
+PUBLIC void free_bit(bit_nr, bitmap, nr_bits) 
+bit_t bit_nr;
+bitchunk_t *bitmap;
+bit_t nr_bits;
+{
+  bitchunk_t *chunk;
+  if (bit_nr >= nr_bits) {
+  	kprintf("Warning, free_bit: %d illegal index\n", bit_nr);
+  	return;
+  }
+  chunk = &bitmap[(bit_nr/BITCHUNK_BITS)];
+  *chunk &= ~(1 << (bit_nr % BITCHUNK_BITS));
+}
+
+/*===========================================================================*
+ *			   	alloc_bit				     * 
+ *===========================================================================*/
+PUBLIC int alloc_bit(bitmap, nr_bits) 
+bitchunk_t *bitmap;
+bit_t nr_bits;
+{
+    bitchunk_t *chunk;
+    int nr_chunks;
+    int bit_nr;
+    int i;
+    
+    /* Iterate over the words in block. */
+    nr_chunks = BITMAP_CHUNKS(nr_bits);
+    for (chunk = &bitmap[0]; chunk < &bitmap[nr_chunks]; chunk++) {
+
+        /* Does this chunk contain a free bit? */
+        if (*chunk == (bitchunk_t) ~0) continue;
+        
+        /* Get bit number from the start of the bit map. */
+        for (i = 0; (*chunk & (1 << i)) != 0; ++i) {}
+        bit_nr = (chunk - &bitmap[0]) * BITCHUNK_BITS + i;
+        
+        /* Don't allocate bits beyond the end of the map. */
+        if (bit_nr >= nr_bits) break;
+
+        *chunk |= 1 << bit_nr % BITCHUNK_BITS;
+        return(bit_nr);        
+        
+    }
+    kprintf("Warning, all %d bits in map busy\n", nr_bits);
+    return(-1);    
+}
+
+
+
+
 #if !NDEBUG
 /*=========================================================================*
  *				bad_assertion				   *