system.c

操作系统课程设计 在minix3下实现实时进程

      krandom.bin[source].r_buf[r_next] = read_clock();
  }
  if (krandom.bin[source].r_size < RANDOM_ELEMENTS) {
  	krandom.bin[source].r_size ++;
  }
  krandom.bin[source].r_next = (r_next + 1 ) % RANDOM_ELEMENTS;
}

/*===========================================================================*
 *				send_sig				     *
 *===========================================================================*/
PUBLIC void send_sig(proc_nr, sig_nr)
int proc_nr;			/* system process to be signalled */
int sig_nr;			/* signal to be sent, 1 to _NSIG */
{
/* Notify a system process about a signal. This is straightforward. Simply
 * set the signal that is to be delivered in the pending signals map and 
 * send a notification with source SYSTEM.
 */ 
  register struct proc *rp;

  rp = proc_addr(proc_nr);
  sigaddset(&priv(rp)->s_sig_pending, sig_nr);
  lock_notify(SYSTEM, proc_nr); 
}

/*===========================================================================*
 *				cause_sig				     *
 *===========================================================================*/
PUBLIC void cause_sig(proc_nr, sig_nr)
int proc_nr;			/* process to be signalled */
int sig_nr;			/* signal to be sent, 1 to _NSIG */
{
/* A system process wants to send a signal to a process.  Examples are:
 *  - HARDWARE wanting to cause a SIGSEGV after a CPU exception
 *  - TTY wanting to cause SIGINT upon getting a DEL
 *  - FS wanting to cause SIGPIPE for a broken pipe 
 * Signals are handled by sending a message to PM.  This function handles the 
 * signals and makes sure the PM gets them by sending a notification. The 
 * process being signaled is blocked while PM has not finished all signals 
 * for it. 
 * Race conditions between calls to this function and the system calls that
 * process pending kernel signals cannot exist. Signal related functions are
 * only called when a user process causes a CPU exception and from the kernel 
 * process level, which runs to completion.
 */
  register struct proc *rp;

  /* Check if the signal is already pending. Process it otherwise. */
  rp = proc_addr(proc_nr);
  if (! sigismember(&rp->p_pending, sig_nr)) {
      sigaddset(&rp->p_pending, sig_nr);
      if (! (rp->p_rts_flags & SIGNALED)) {		/* other pending */
          if (rp->p_rts_flags == 0) lock_dequeue(rp);	/* make not ready */
          rp->p_rts_flags |= SIGNALED | SIG_PENDING;	/* update flags */
          send_sig(PM_PROC_NR, SIGKSIG);
      }
  }
}

/*===========================================================================*
 *				umap_bios				     *
 *===========================================================================*/
PUBLIC phys_bytes umap_bios(rp, vir_addr, bytes)
register struct proc *rp;	/* pointer to proc table entry for process */
vir_bytes vir_addr;		/* virtual address in BIOS segment */
vir_bytes bytes;		/* # of bytes to be copied */
{
/* Calculate the physical memory address at the BIOS. Note: currently, BIOS
 * address zero (the first BIOS interrupt vector) is not considered, as an 
 * error here, but since the physical address will be zero as well, the 
 * calling function will think an error occurred. This is not a problem,
 * since no one uses the first BIOS interrupt vector.  
 */

  /* Check all acceptable ranges. */
  if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= BIOS_MEM_END)
  	return (phys_bytes) vir_addr;
  else if (vir_addr >= BASE_MEM_TOP && vir_addr + bytes <= UPPER_MEM_END)
  	return (phys_bytes) vir_addr;

#if DEAD_CODE	/* brutal fix, if the above is too restrictive */
  if (vir_addr >= BIOS_MEM_BEGIN && vir_addr + bytes <= UPPER_MEM_END)
  	return (phys_bytes) vir_addr;
#endif

  kprintf("Warning, error in umap_bios, virtual address 0x%x\n", vir_addr);
  return 0;
}

/*===========================================================================*
 *				umap_local				     *
 *===========================================================================*/
PUBLIC phys_bytes umap_local(rp, seg, vir_addr, bytes)
register struct proc *rp;	/* pointer to proc table entry for process */
int seg;			/* T, D, or S segment */
vir_bytes vir_addr;		/* virtual address in bytes within the seg */
vir_bytes bytes;		/* # of bytes to be copied */
{
/* Calculate the physical memory address for a given virtual address. */
  vir_clicks vc;		/* the virtual address in clicks */
  phys_bytes pa;		/* intermediate variables as phys_bytes */
#if (CHIP == INTEL)
  phys_bytes seg_base;
#endif

  /* If 'seg' is D it could really be S and vice versa.  T really means T.
   * If the virtual address falls in the gap,  it causes a problem. On the
   * 8088 it is probably a legal stack reference, since "stackfaults" are
   * not detected by the hardware.  On 8088s, the gap is called S and
   * accepted, but on other machines it is called D and rejected.
   * The Atari ST behaves like the 8088 in this respect.
   */

  if (bytes <= 0) return( (phys_bytes) 0);
  if (vir_addr + bytes <= vir_addr) return 0;	/* overflow */
  vc = (vir_addr + bytes - 1) >> CLICK_SHIFT;	/* last click of data */

#if (CHIP == INTEL) || (CHIP == M68000)
  if (seg != T)
	seg = (vc < rp->p_memmap[D].mem_vir + rp->p_memmap[D].mem_len ? D : S);
#else
  if (seg != T)
	seg = (vc < rp->p_memmap[S].mem_vir ? D : S);
#endif

  if ((vir_addr>>CLICK_SHIFT) >= rp->p_memmap[seg].mem_vir + 
  	rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );

  if (vc >= rp->p_memmap[seg].mem_vir + 
  	rp->p_memmap[seg].mem_len) return( (phys_bytes) 0 );

#if (CHIP == INTEL)
  seg_base = (phys_bytes) rp->p_memmap[seg].mem_phys;
  seg_base = seg_base << CLICK_SHIFT;	/* segment origin in bytes */
#endif
  pa = (phys_bytes) vir_addr;
#if (CHIP != M68000)
  pa -= rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
  return(seg_base + pa);
#endif
#if (CHIP == M68000)
  pa -= (phys_bytes)rp->p_memmap[seg].mem_vir << CLICK_SHIFT;
  pa += (phys_bytes)rp->p_memmap[seg].mem_phys << CLICK_SHIFT;
  return(pa);
#endif
}

/*===========================================================================*
 *				umap_remote				     *
 *===========================================================================*/
PUBLIC phys_bytes umap_remote(rp, seg, vir_addr, bytes)
register struct proc *rp;	/* pointer to proc table entry for process */
int seg;			/* index of remote segment */
vir_bytes vir_addr;		/* virtual address in bytes within the seg */
vir_bytes bytes;		/* # of bytes to be copied */
{
/* Calculate the physical memory address for a given virtual address. */
  struct far_mem *fm;

  if (bytes <= 0) return( (phys_bytes) 0);
  if (seg < 0 || seg >= NR_REMOTE_SEGS) return( (phys_bytes) 0);

  fm = &rp->p_priv->s_farmem[seg];
  if (! fm->in_use) return( (phys_bytes) 0);
  if (vir_addr + bytes > fm->mem_len) return( (phys_bytes) 0);

  return(fm->mem_phys + (phys_bytes) vir_addr); 
}

/*===========================================================================*
 *				virtual_copy				     *
 *===========================================================================*/
PUBLIC int virtual_copy(src_addr, dst_addr, bytes)
struct vir_addr *src_addr;	/* source virtual address */
struct vir_addr *dst_addr;	/* destination virtual address */
vir_bytes bytes;		/* # of bytes to copy  */
{
/* Copy bytes from virtual address src_addr to virtual address dst_addr. 
 * Virtual addresses can be in ABS, LOCAL_SEG, REMOTE_SEG, or BIOS_SEG.
 */
  struct vir_addr *vir_addr[2];	/* virtual source and destination address */
  phys_bytes phys_addr[2];	/* absolute source and destination */ 
  int seg_index;
  int i;

  /* Check copy count. */
  if (bytes <= 0) return(EDOM);

  /* Do some more checks and map virtual addresses to physical addresses. */
  vir_addr[_SRC_] = src_addr;
  vir_addr[_DST_] = dst_addr;
  for (i=_SRC_; i<=_DST_; i++) {

      /* Get physical address. */
      switch((vir_addr[i]->segment & SEGMENT_TYPE)) {
      case LOCAL_SEG:
          seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
          phys_addr[i] = umap_local( proc_addr(vir_addr[i]->proc_nr), 
              seg_index, vir_addr[i]->offset, bytes );
          break;
      case REMOTE_SEG:
          seg_index = vir_addr[i]->segment & SEGMENT_INDEX;
          phys_addr[i] = umap_remote( proc_addr(vir_addr[i]->proc_nr), 
              seg_index, vir_addr[i]->offset, bytes );
          break;
      case BIOS_SEG:
          phys_addr[i] = umap_bios( proc_addr(vir_addr[i]->proc_nr),
              vir_addr[i]->offset, bytes );
          break;
      case PHYS_SEG:
          phys_addr[i] = vir_addr[i]->offset;
          break;
      default:
          return(EINVAL);
      }

      /* Check if mapping succeeded. */
      if (phys_addr[i] <= 0 && vir_addr[i]->segment != PHYS_SEG) 
          return(EFAULT);
  }

  /* Now copy bytes between physical addresseses. */
  phys_copy(phys_addr[_SRC_], phys_addr[_DST_], (phys_bytes) bytes);
  return(OK);
}