flight/libraries/PyMite/vm/pm.c

   1 /*
   2 # This file is Copyright 2006, 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 #undef __FILE_ID__
  17 #define __FILE_ID__ 0x15
  18
  19
  20 /**
  21  * \file
  22  * \brief PyMite User API
  23  *
  24  * High-level functions to initialize and run PyMite
  25  */
  26
  27
  28 #include "pm.h"
  29
  30
  31 /** Number of millisecond-ticks to pass before scheduler is run */
  32 #define PM_THREAD_TIMESLICE_MS  10
  33
  34
  35 /** Stores the timer millisecond-ticks since system start */
  36 volatile uint32_t pm_timerMsTicks = 0;
  37
  38 /** Stores tick timestamp of last scheduler run */
  39 volatile uint32_t pm_lastRescheduleTimestamp = 0;
  40
  41
  42 PmReturn_t
  43 pm_init(PmMemSpace_t memspace, uint8_t const * const pusrimg)
  44 {
  45     PmReturn_t retval;
  46
  47     /* Initialize the hardware platform */
  48     retval = plat_init();
  49     PM_RETURN_IF_ERROR(retval);
  50
  51     /* Initialize the heap and the globals */
  52     retval = heap_init();
  53     PM_RETURN_IF_ERROR(retval);
  54
  55     retval = global_init();
  56     PM_RETURN_IF_ERROR(retval);
  57
  58     /* Load usr image info if given */
  59     if (pusrimg != C_NULL)
  60     {
  61         retval = img_appendToPath(memspace, pusrimg);
  62     }
  63
  64     return retval;
  65 }
  66
  67
  68 PmReturn_t
  69 pm_run(uint8_t const *modstr)
  70 {
  71     PmReturn_t retval;
  72     pPmObj_t pmod;
  73     pPmObj_t pstring;
  74     uint8_t const *pmodstr = modstr;
  75
  76     /* Import module from global struct */
  77     retval = string_new(&pmodstr, &pstring);
  78     PM_RETURN_IF_ERROR(retval);
  79     retval = mod_import(pstring, &pmod);
  80     PM_RETURN_IF_ERROR(retval);
  81
  82     /* Load builtins into thread */
  83     retval = global_setBuiltins((pPmFunc_t)pmod);
  84     PM_RETURN_IF_ERROR(retval);
  85
  86     /* Interpret the module's bcode */
  87     retval = interp_addThread((pPmFunc_t)pmod);
  88     PM_RETURN_IF_ERROR(retval);
  89     retval = interpret(INTERP_RETURN_ON_NO_THREADS);
  90
  91     /*
  92      * De-initialize the hardware platform.
  93      * Ignore plat_deinit's retval so interpret's retval returns to caller.
  94      */
  95     plat_deinit();
  96
  97     return retval;
  98 }
  99
 100
 101 /* Warning: Can be called in interrupt context! */
 102 PmReturn_t
 103 pm_vmPeriodic(uint16_t usecsSinceLastCall)
 104 {
 105     /*
 106      * Add the full milliseconds to pm_timerMsTicks and store additional
 107      * microseconds for the next run. Thus, usecsSinceLastCall must be
 108      * less than 2^16-1000 so it will not overflow usecResidual.
 109      */
 110     static uint16_t usecResidual = 0;
 111
 112     C_ASSERT(usecsSinceLastCall < 64536);
 113
 114     usecResidual += usecsSinceLastCall;
 115     while (usecResidual >= 1000)
 116     {
 117         usecResidual -= 1000;
 118         pm_timerMsTicks++;
 119     }
 120
 121     /* Check if enough time has passed for a scheduler run */
 122     if ((pm_timerMsTicks - pm_lastRescheduleTimestamp)
 123         >= PM_THREAD_TIMESLICE_MS)
 124     {
 125         interp_setRescheduleFlag((uint8_t)1);
 126         pm_lastRescheduleTimestamp = pm_timerMsTicks;
 127     }
 128     return PM_RET_OK;
 129 }