flight/libraries/PyMite/vm/thread.h

   1 /*
   2 # This file is Copyright 2007, 2009, 2010 Dean Hall.
   3 #
   4 # This file is part of the PyMite VM.
   5 # The PyMite VM is free software: you can redistribute it and/or modify
   6 # it under the terms of the GNU GENERAL PUBLIC LICENSE Version 2.
   7 #
   8 # The PyMite VM is distributed in the hope that it will be useful,
   9 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11 # A copy of the GNU GENERAL PUBLIC LICENSE Version 2
  12 # is seen in the file COPYING in this directory.
  13 */
  14
  15
  16 #ifndef __THREAD_H__
  17 #define __THREAD_H__
  18
  19
  20 /**
  21  * \file
  22  * \brief VM Thread
  23  *
  24  * Encapsulating a frame pointer, a root code object and thread state.
  25  */
  26
  27
  28 #include "interp.h"
  29
  30
  31  /** Frequency in Hz to switch threads */
  32 #define THREAD_RESCHEDULE_FREQUENCY    10
  33
  34
  35 /**
  36  * Interpreter return values
  37  *
  38  * Used to control interpreter loop
  39  * and indicate return value.
  40  * Negative values indicate erroneous results.
  41  * Positive values indicate "continue interpreting",
  42  * but first do something special like reschedule threads
  43  * or (TBD) sweep the heap.
  44  */
  45 typedef enum PmInterpCtrl_e
  46 {
  47     /* other erroneous exits go here with negative values */
  48     INTERP_CTRL_ERR = -1,   /**< Generic error causes exit */
  49     INTERP_CTRL_EXIT = 0,   /**< Normal execution exit */
  50     INTERP_CTRL_CONT = 1,   /**< Continue interpreting */
  51     INTERP_CTRL_RESCHED = 2 /**< Reschedule threads */
  52         /* all positive values indicate "continue interpreting" */
  53 } PmInterpCtrl_t, *pPmInterpCtrl_t;
  54
  55 /**
  56  * Thread obj
  57  *
  58  */
  59 typedef struct PmThread_s
  60 {
  61     /** object descriptor */
  62     PmObjDesc_t od;
  63
  64     /** current frame pointer */
  65     pPmFrame_t pframe;
  66
  67     /**
  68      * Interpreter loop control value
  69      *
  70      * A positive value means continue interpreting.
  71      * A zero value means normal interpreter exit.
  72      * A negative value signals an error exit.
  73      */
  74     PmInterpCtrl_t interpctrl;
  75 } PmThread_t,
  76  *pPmThread_t;
  77
  78
  79 /**
  80  * Constructs a thread for a root frame.
  81  *
  82  * @param pframe Frame object as a basis for this thread.
  83  * @param r_pobj Return by reference; Ptr to the newly created thread object.
  84  * @return Return status
  85  */
  86 PmReturn_t thread_new(pPmObj_t pframe, pPmObj_t *r_pobj);
  87
  88 #endif /* __THREAD_H__ */