frame.h

00001 /*
00002 # This file is Copyright 2003, 2006, 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 __FRAME_H__
00017 #define __FRAME_H__
00018 
00019 
00020 /**
00021  * \file
00022  * \brief VM Frame
00023  *
00024  * VM frame header.
00025  */
00026 
00027 
00028 /**
00029  * The maximum number of local variables a native function can have.
00030  * This defines the length of the locals array in the native frame struct.
00031  */
00032 #define NATIVE_MAX_NUM_LOCALS   8
00033 
00034 
00035 /**
00036  * Block Type
00037  *
00038  * Numerical values to put in the 'b_type' field of the tPmBlockType struct.
00039  */
00040 typedef enum PmBlockType_e
00041 {
00042     /** Invalid block type */
00043     B_INVALID = 0,
00044 
00045     /** Loop type */
00046     B_LOOP,
00047 
00048     /** Try type */
00049     B_TRY
00050 } PmBlockType_t, *pPmBlockType_t;
00051 
00052 
00053 /**
00054  * Block
00055  *
00056  * Extra info for loops and trys (others?)
00057  * Frames use linked list of blocks to handle
00058  * nested loops and try-catch blocks.
00059  */
00060 typedef struct PmBlock_s
00061 {
00062     /** Obligatory obj descriptor */
00063     PmObjDesc_t od;
00064 
00065     /** Ptr to backup stack ptr */
00066     pPmObj_t *b_sp;
00067 
00068     /** Handler fxn obj */
00069     uint8_t const *b_handler;
00070 
00071     /** Block type */
00072     PmBlockType_t b_type:8;
00073 
00074     /** Next block in stack */
00075     struct PmBlock_s *next;
00076 } PmBlock_t,
00077  *pPmBlock_t;
00078 
00079 
00080 /**
00081  * Frame
00082  *
00083  * A struct that holds the execution frame of a function, including the stack,
00084  * local vars and pointer to the code object.
00085  *
00086  * This struct doesn't declare the stack.
00087  * frame_new() is responsible for allocating the extra memory
00088  * at the tail of fo_locals[] to hold both the locals and stack.
00089  */
00090 typedef struct PmFrame_s
00091 {
00092     /** Obligatory obj descriptor */
00093     PmObjDesc_t od;
00094 
00095     /** Ptr to previous frame obj */
00096     struct PmFrame_s *fo_back;
00097 
00098     /** Ptr to fxn obj */
00099     pPmFunc_t fo_func;
00100 
00101     /** Mem space where func's CO comes from */
00102     PmMemSpace_t fo_memspace:8;
00103 
00104     /** Instrxn ptr (pts into memspace) */
00105     uint8_t const *fo_ip;
00106 
00107     /** Linked list of blocks */
00108     pPmBlock_t fo_blockstack;
00109 
00110     /** Local attributes dict (non-fast locals) */
00111     pPmDict_t fo_attrs;
00112 
00113     /** Global attributes dict (pts to root frame's globals */
00114     pPmDict_t fo_globals;
00115 
00116     /** Points to next empty slot in fo_locals (1 past TOS) */
00117     pPmObj_t *fo_sp;
00118 
00119     /** Frame can be an import-frame that handles RETURN differently */
00120     uint8_t fo_isImport:1;
00121 
00122 #ifdef HAVE_CLASSES
00123     /** Flag to indicate class initailzer frame; handle RETURN differently */
00124     uint8_t fo_isInit:1;
00125 #endif /* HAVE_CLASSES */
00126 
00127     /** Array of local vars and stack (space appended at alloc) */
00128     pPmObj_t fo_locals[1];
00129     /* WARNING: Do not put new fields below fo_locals */
00130 } PmFrame_t,
00131  *pPmFrame_t;
00132 
00133 
00134 /**
00135  * Native Frame
00136  *
00137  * A struct that holds the execution frame of a native function,
00138  * including the args and single stack slot, and pointer to the code object.
00139  *
00140  * This struct doesn't need an OD because it is only used statically in the
00141  * globals struct.  There's only one native frame, the global one.
00142  * This happens because a native function is a leaf node
00143  * in the call tree (a native func can't call python funcs).
00144  */
00145 typedef struct PmNativeFrame_s
00146 {
00147     /** Object descriptor */
00148     PmObjDesc_t od;
00149 
00150     /** Ptr to previous frame obj */
00151     struct PmFrame_s *nf_back;
00152 
00153     /** Ptr to fxn obj */
00154     pPmFunc_t nf_func;
00155 
00156     /** Single stack slot */
00157     pPmObj_t nf_stack;
00158 
00159     /** Boolean to indicate if the native frame is active */
00160     uint8_t nf_active;
00161 
00162     /** Number of args passed to the native function */
00163     uint8_t nf_numlocals;
00164 
00165     /** Local vars */
00166     pPmObj_t nf_locals[NATIVE_MAX_NUM_LOCALS];
00167 } PmNativeFrame_t,
00168  *pPmNativeFrame_t;
00169 
00170 
00171 /**
00172  * Allocate space for a new frame, fill its fields
00173  * with respect to the given function object.
00174  * Return pointer to the new frame.
00175  *
00176  * @param   pfunc ptr to Function object.
00177  * @param   r_pobj Return value; the new frame.
00178  * @return  Return status.
00179  */
00180 PmReturn_t frame_new(pPmObj_t pfunc, pPmObj_t *r_pobj);
00181 
00182 #endif /* __FRAME_H__ */