/* Copyright (C) 2005 David Decotigny
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 
 #include <sos/assert.h>
 #include <sos/list.h>
 #include <sos/kmem_slab.h>
 #include <hwcore/irq.h>
 #include <drivers/bochs.h>
 
 #include <hwcore/mm_context.h>
 
 #include "process.h"
 
 
 #define SOS_PROCESS_MAX_NAMELEN 32
 
 
 /**
  * Definition of a process in SOS. A process is basically the
  * collection of all the resources requested by a user program. The
  * threads are one of these resources, the mm_context is one other
  * example of such resources.
  */
 struct sos_process
 {
   char name[SOS_PROCESS_MAX_NAMELEN];
 
   /** First important resource: the MMU translation tables'
       configuration */
   struct sos_mm_context  *mm_context;
 
   /** Second important resource: the CPU execution contexts, aka the
       threads executing in the context of this process. */
   struct sos_thread      *thread_list;
   sos_count_t            nb_threads;
 
   /** Reference counter, including threads */
   sos_count_t            ref_cnt;
 
   struct sos_process     *prev, *next;
 };
 
 
 /** The list of processes in the system */
 static struct sos_process *process_list = NULL;
 
 
 /** The cache for the sos_process structures */
 struct sos_kslab_cache *cache_struct_process;
 
 
 /**
  * Helper function for debugging purposes
  */
 void sos_process_dumplist()
 {
   struct sos_thread * cur_thr = sos_thread_get_current();
   struct sos_process * proc;
   int nb_procs;
 
   sos_bochs_printf("<ps>\n");
   list_foreach(process_list, proc, nb_procs)
     {
       struct sos_thread * thr;
       int    nb_thrs;
 
       sos_bochs_printf("  proc@%p: '%s', %d threads, %d refs\n",
                        proc, proc->name?proc->name:"(none)",
                        proc->nb_threads, proc->ref_cnt);
 
       list_foreach_forward_named(proc->thread_list, thr, nb_thrs,
                                  prev_in_process, next_in_process)
         {
           if (thr == cur_thr)
             sos_bochs_printf("    thr@%p: [CURRENT]\n", thr);
           else
             sos_bochs_printf("    thr@%p: %cstate=%d eip=%p\n",
                              thr,
                              sos_cpu_context_is_in_user_mode(thr->cpu_state)?'u':'k',
                              thr->state,
                              (void*)sos_cpu_context_get_PC(thr->cpu_state));
         }
     }
   sos_bochs_printf("  ======= %d processes =======\n", nb_procs);
   sos_bochs_printf("</ps>\n");
 }
 
 
 sos_ret_t sos_process_subsystem_setup()
 {
   /* Create the cache for the process structures */
   cache_struct_process = sos_kmem_cache_create("struct_process",
                                                sizeof(struct sos_process),
                                                3,
                                                0,
                                                SOS_KSLAB_CREATE_MAP
                                                | SOS_KSLAB_CREATE_ZERO);
   if (! cache_struct_process)
     return -SOS_ENOMEM;
 
   return SOS_OK;
 }
 
 
 struct sos_process *sos_process_create_empty(const char *name)
 {
   sos_ui32_t flags;
   struct sos_process *proc;
 
   proc = (struct sos_process*) sos_kmem_cache_alloc(cache_struct_process, 0);
   if (! proc)
     return NULL;
 
   /* proc is already filled with 0 (cache has SOS_KSLAB_CREATE_ZERO
      flag) */
 
   /* Initialize a new mm_context */
   proc->mm_context = sos_mm_context_create();
   if (NULL == proc->mm_context)
     {
       /* Error */
       sos_kmem_cache_free((sos_vaddr_t)proc);
       return NULL;
     }
 
   if (!name)
     {
         name = "[UNNAMED]";
     }
 
   strzcpy(proc->name, name, SOS_PROCESS_MAX_NAMELEN);
 
   /* Add it to the global list of processes */
   sos_disable_IRQs(flags);
   list_add_tail(process_list, proc);
   sos_restore_IRQs(flags);
 
   /* Mark the process as referenced */
   proc->ref_cnt = 1;
   return proc;
 }
 
 
 inline
 sos_ret_t sos_process_ref(struct sos_process *proc)
 {
   sos_ui32_t flags;
   sos_disable_IRQs(flags);
   proc->ref_cnt ++;
   sos_restore_IRQs(flags);
   return SOS_OK;
 }
 
 
 sos_count_t sos_process_get_nb_threads(const struct sos_process *proc)
 {
   sos_count_t retval;
   sos_ui32_t flags;
   sos_disable_IRQs(flags);
   retval = proc->nb_threads;
   sos_restore_IRQs(flags);
   return retval;
 }
 
 
 struct sos_mm_context *
 sos_process_get_mm_context(const struct sos_process *proc)
 {
   return proc->mm_context;
 }
 
 
 /* ***************************************************
  * Restricted functions
  */
 
 
 sos_ret_t sos_process_register_thread(struct sos_process *in_proc,
                                       struct sos_thread *thr)
 {
   sos_ui32_t flags;
 
   /* The process is assumed to be referenced by somebody */
   SOS_ASSERT_FATAL(in_proc->ref_cnt > 0);
 
   /* Only threads that are being created are allowed to be attached to
      a process */
   SOS_ASSERT_FATAL(thr->state == SOS_THR_CREATED);
 
   /* Update the list of the threads in the process */
   thr->process = in_proc;
 
   /* Increment the reference count for the process */
   sos_process_ref(in_proc);
 
   /* Add the thread to the process thread's list */
   sos_disable_IRQs(flags);
   list_add_tail_named(in_proc->thread_list, thr,
                       prev_in_process, next_in_process);
   in_proc->nb_threads ++;
   sos_restore_IRQs(flags);
 
   return SOS_OK;
 }
 
 
 /** The function responsible for releasing the resources held by the
     process. */
 sos_ret_t sos_process_unref(struct sos_process *proc)
 {
   sos_ui32_t flags;
   sos_ret_t retval;
 
   SOS_ASSERT_FATAL(proc->ref_cnt > 0);
 
   sos_disable_IRQs(flags);
   proc->ref_cnt --;
   if (proc->ref_cnt > 0)
     {
       sos_restore_IRQs(flags);
       return -SOS_EBUSY;
     }
   list_delete(process_list, proc);
   sos_restore_IRQs(flags);
 
   /* First: release the mm_context */
   retval = sos_mm_context_unref(proc->mm_context);
   SOS_ASSERT_FATAL(SOS_OK == retval);
 
   /* Free the process structure */
   sos_kmem_cache_free((sos_vaddr_t)proc);
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_process_unregister_thread(struct sos_thread *thr)
 {
   sos_ui32_t flags;
   struct sos_process * in_proc = thr->process;
 
   SOS_ASSERT_FATAL(thr->state == SOS_THR_ZOMBIE);
   
   /* Update the list of the threads in the process */
   thr->process = NULL;
   sos_disable_IRQs(flags);
   list_delete_named(in_proc->thread_list, thr,
                     prev_in_process, next_in_process);
   SOS_ASSERT_FATAL(in_proc->nb_threads > 0);
   in_proc->nb_threads --;
   sos_restore_IRQs(flags);
  
   /* Unreference the process */
   sos_process_unref(in_proc);
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_process_set_name(struct sos_process * proc,
                                const char * new_name)
 {
   strzcpy(proc->name, new_name, SOS_PROCESS_MAX_NAMELEN);
   return SOS_OK;
 }