flight/libraries/PyMite/vm/frame.h

   1 /*
   2 # This file is Copyright 2003, 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 #ifndef __FRAME_H__
  17 #define __FRAME_H__
  18
  19
  20 /**
  21  * \file
  22  * \brief VM Frame
  23  *
  24  * VM frame header.
  25  */
  26
  27
  28 /**
  29  * The maximum number of local variables a native function can have.
  30  * This defines the length of the locals array in the native frame struct.
  31  */
  32 #define NATIVE_MAX_NUM_LOCALS   8
  33
  34
  35 /**
  36  * Block Type
  37  *
  38  * Numerical values to put in the 'b_type' field of the tPmBlockType struct.
  39  */
  40 typedef enum PmBlockType_e
  41 {
  42     /** Invalid block type */
  43     B_INVALID = 0,
  44
  45     /** Loop type */
  46     B_LOOP,
  47
  48     /** Try type */
  49     B_TRY
  50 } PmBlockType_t, *pPmBlockType_t;
  51
  52
  53 /**
  54  * Block
  55  *
  56  * Extra info for loops and trys (others?)
  57  * Frames use linked list of blocks to handle
  58  * nested loops and try-catch blocks.
  59  */
  60 typedef struct PmBlock_s
  61 {
  62     /** Obligatory obj descriptor */
  63     PmObjDesc_t od;
  64
  65     /** Ptr to backup stack ptr */
  66     pPmObj_t *b_sp;
  67
  68     /** Handler fxn obj */
  69     uint8_t const *b_handler;
  70
  71     /** Block type */
  72     PmBlockType_t b_type:8;
  73
  74     /** Next block in stack */
  75     struct PmBlock_s *next;
  76 } PmBlock_t,
  77  *pPmBlock_t;
  78
  79
  80 /**
  81  * Frame
  82  *
  83  * A struct that holds the execution frame of a function, including the stack,
  84  * local vars and pointer to the code object.
  85  *
  86  * This struct doesn't declare the stack.
  87  * frame_new() is responsible for allocating the extra memory
  88  * at the tail of fo_locals[] to hold both the locals and stack.
  89  */
  90 typedef struct PmFrame_s
  91 {
  92     /** Obligatory obj descriptor */
  93     PmObjDesc_t od;
  94
  95     /** Ptr to previous frame obj */
  96     struct PmFrame_s *fo_back;
  97
  98     /** Ptr to fxn obj */
  99     pPmFunc_t fo_func;
 100
 101     /** Mem space where func's CO comes from */
 102     PmMemSpace_t fo_memspace:8;
 103
 104     /** Instrxn ptr (pts into memspace) */
 105     uint8_t const *fo_ip;
 106
 107     /** Linked list of blocks */
 108     pPmBlock_t fo_blockstack;
 109
 110     /** Local attributes dict (non-fast locals) */
 111     pPmDict_t fo_attrs;
 112
 113     /** Global attributes dict (pts to root frame's globals */
 114     pPmDict_t fo_globals;
 115
 116     /** Points to next empty slot in fo_locals (1 past TOS) */
 117     pPmObj_t *fo_sp;
 118
 119     /** Frame can be an import-frame that handles RETURN differently */
 120     uint8_t fo_isImport:1;
 121
 122 #ifdef HAVE_CLASSES
 123     /** Flag to indicate class initailzer frame; handle RETURN differently */
 124     uint8_t fo_isInit:1;
 125 #endif /* HAVE_CLASSES */
 126
 127     /** Array of local vars and stack (space appended at alloc) */
 128     pPmObj_t fo_locals[1];
 129     /* WARNING: Do not put new fields below fo_locals */
 130 } PmFrame_t,
 131  *pPmFrame_t;
 132
 133
 134 /**
 135  * Native Frame
 136  *
 137  * A struct that holds the execution frame of a native function,
 138  * including the args and single stack slot, and pointer to the code object.
 139  *
 140  * This struct doesn't need an OD because it is only used statically in the
 141  * globals struct.  There's only one native frame, the global one.
 142  * This happens because a native function is a leaf node
 143  * in the call tree (a native func can't call python funcs).
 144  */
 145 typedef struct PmNativeFrame_s
 146 {
 147     /** Object descriptor */
 148     PmObjDesc_t od;
 149
 150     /** Ptr to previous frame obj */
 151     struct PmFrame_s *nf_back;
 152
 153     /** Ptr to fxn obj */
 154     pPmFunc_t nf_func;
 155
 156     /** Single stack slot */
 157     pPmObj_t nf_stack;
 158
 159     /** Boolean to indicate if the native frame is active */
 160     uint8_t nf_active;
 161
 162     /** Number of args passed to the native function */
 163     uint8_t nf_numlocals;
 164
 165     /** Local vars */
 166     pPmObj_t nf_locals[NATIVE_MAX_NUM_LOCALS];
 167 } PmNativeFrame_t,
 168  *pPmNativeFrame_t;
 169
 170
 171 /**
 172  * Allocate space for a new frame, fill its fields
 173  * with respect to the given function object.
 174  * Return pointer to the new frame.
 175  *
 176  * @param   pfunc ptr to Function object.
 177  * @param   r_pobj Return value; the new frame.
 178  * @return  Return status.
 179  */
 180 PmReturn_t frame_new(pPmObj_t pfunc, pPmObj_t *r_pobj);
 181
 182 #endif /* __FRAME_H__ */