thread.h

00001 /*
00002 # This file is Copyright 2007, 2009 Dean Hall.
00003 #
00004 # This file is part of the PyMite VM.
00005 # The PyMite VM is free software: you can redistribute it and/or modify
00006 # it under the terms of the GNU GENERAL PUBLIC LICENSE Version 2.
00007 #
00008 # The PyMite VM is distributed in the hope that it will be useful,
00009 # but WITHOUT ANY WARRANTY; without even the implied warranty of
00010 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
00011 # A copy of the GNU GENERAL PUBLIC LICENSE Version 2
00012 # is seen in the file COPYING in this directory.
00013 */
00014 
00015 
00016 #ifndef __THREAD_H__
00017 #define __THREAD_H__
00018 
00019 
00020 /**
00021  * \file
00022  * \brief VM Thread
00023  *
00024  * Encapsulating a frame pointer, a root code object and thread state.
00025  */
00026 
00027 
00028 #include "interp.h"
00029 
00030 
00031  /** Frequency in Hz to switch threads */
00032 #define THREAD_RESCHEDULE_FREQUENCY    10
00033 
00034 
00035 /**
00036  * Interpreter return values
00037  *
00038  * Used to control interpreter loop
00039  * and indicate return value.
00040  * Negative values indicate erroneous results.
00041  * Positive values indicate "continue interpreting",
00042  * but first do something special like reschedule threads
00043  * or (TBD) sweep the heap.
00044  */
00045 typedef enum PmInterpCtrl_e
00046 {
00047     /* other erroneous exits go here with negative values */
00048     INTERP_CTRL_ERR = -1,   /**< Generic error causes exit */
00049     INTERP_CTRL_EXIT = 0,   /**< Normal execution exit */
00050     INTERP_CTRL_CONT = 1,   /**< Continue interpreting */
00051     INTERP_CTRL_RESCHED = 2 /**< Reschedule threads */
00052         /* all positive values indicate "continue interpreting" */
00053 } PmInterpCtrl_t, *pPmInterpCtrl_t;
00054 
00055 /**
00056  * Thread obj
00057  *
00058  */
00059 typedef struct PmThread_s
00060 {
00061     /** object descriptor */
00062     PmObjDesc_t od;
00063 
00064     /** current frame pointer */
00065     pPmFrame_t pframe;
00066 
00067     /**
00068      * Interpreter loop control value
00069      *
00070      * A positive value means continue interpreting.
00071      * A zero value means normal interpreter exit.
00072      * A negative value signals an error exit.
00073      */
00074     PmInterpCtrl_t interpctrl;
00075 } PmThread_t,
00076  *pPmThread_t;
00077 
00078 
00079 /**
00080  * Constructs a thread for a root frame.
00081  *
00082  * @param pframe Frame object as a basis for this thread.
00083  * @param r_pobj Return by reference; Ptr to the newly created thread object.
00084  * @return Return status
00085  */
00086 PmReturn_t thread_new(pPmObj_t pframe, pPmObj_t *r_pobj);
00087 
00088 #endif /* __THREAD_H__ */