minix/kernel/utility.c
2005-07-14 15:27:40 +00:00

115 lines
3.2 KiB
C
Executable file

/* This file contains a collection of miscellaneous procedures:
* panic abort MINIX due to a fatal error
* safe_lock lock the kernel, use in combination with safe_unlock
* safe_unlock unlock the kernel, but prevent breaking nested locks
* alloc_bit bit map manipulation
* free_bit bit map manipulation
*/
#include "kernel.h"
#include "assert.h"
#include <unistd.h>
#include <minix/com.h>
PRIVATE int relock_count = 0;
/*===========================================================================*
* safe_lock *
*===========================================================================*/
PUBLIC void safe_lock(c,v)
int c;
char *v;
{
if(!(read_cpu_flags() & X86_FLAG_I)) {
relock_count++;
} else {
intr_disable();
}
}
/*===========================================================================*
* safe_unlock *
*===========================================================================*/
PUBLIC void safe_unlock(void)
{
if(! relock_count) {
intr_enable();
} else {
relock_count--;
}
}
/*===========================================================================*
* panic *
*===========================================================================*/
PUBLIC void panic(s,n)
_CONST char *s;
int n;
{
/* The system has run aground of a fatal kernel error. Terminate execution. */
static int panicking = 0;
if (panicking ++) /* prevent recursive panics */
return;
if (s != NULL) {
kprintf("\nKernel panic: %s", karg(s));
if (n != NO_NUM) kprintf(" %d", n);
kprintf("\n",NO_NUM);
}
prepare_shutdown(RBT_PANIC);
}
/*===========================================================================*
* 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);
}
return(-1);
}