frame.h

00001 /*
00002 # This file is Copyright 2002 Dean Hall.
00003 # This file is part of the PyMite VM.
00004 # This file is licensed under the MIT License.
00005 # See the LICENSE file for details.
00006 */
00007 
00008 
00009 #ifndef __FRAME_H__
00010 #define __FRAME_H__
00011 
00012 
00013 /**
00014  * \file
00015  * \brief VM Frame
00016  *
00017  * VM frame header.
00018  */
00019 
00020 
00021 /**
00022  * The maximum number of local variables a native function can have.
00023  * This defines the length of the locals array in the native frame struct.
00024  */
00025 #define NATIVE_MAX_NUM_LOCALS   8
00026 
00027 
00028 /**
00029  * Block Type
00030  *
00031  * Numerical values to put in the 'b_type' field of the tPmBlockType struct.
00032  */
00033 typedef enum PmBlockType_e
00034 {
00035     /** Invalid block type */
00036     B_INVALID = 0,
00037 
00038     /** Loop type */
00039     B_LOOP,
00040 
00041     /** Try type */
00042     B_TRY
00043 } PmBlockType_t, *pPmBlockType_t;
00044 
00045 
00046 /**
00047  * Block
00048  *
00049  * Extra info for loops and trys (others?)
00050  * Frames use linked list of blocks to handle
00051  * nested loops and try-catch blocks.
00052  */
00053 typedef struct PmBlock_s
00054 {
00055     /** Obligatory obj descriptor */
00056     PmObjDesc_t od;
00057 
00058     /** Ptr to backup stack ptr */
00059     pPmObj_t *b_sp;
00060 
00061     /** Handler fxn obj */
00062     uint8_t const *b_handler;
00063 
00064     /** Block type */
00065     PmBlockType_t b_type:8;
00066 
00067     /** Next block in stack */
00068     struct PmBlock_s *next;
00069 } PmBlock_t,
00070  *pPmBlock_t;
00071 
00072 
00073 /**
00074  * Frame
00075  *
00076  * A struct that holds the execution frame of a function, including the stack,
00077  * local vars and pointer to the code object.
00078  *
00079  * This struct doesn't declare the stack.
00080  * frame_new() is responsible for allocating the extra memory
00081  * at the tail of fo_locals[] to hold both the locals and stack.
00082  */
00083 typedef struct PmFrame_s
00084 {
00085     /** Obligatory obj descriptor */
00086     PmObjDesc_t od;
00087 
00088     /** Ptr to previous frame obj */
00089     struct PmFrame_s *fo_back;
00090 
00091     /** Ptr to fxn obj */
00092     pPmFunc_t fo_func;
00093 
00094     /** Mem space where func's CO comes from */
00095     PmMemSpace_t fo_memspace:8;
00096 
00097     /** Instrxn ptr (pts into memspace) */
00098     uint8_t const *fo_ip;
00099 
00100     /** Linked list of blocks */
00101     pPmBlock_t fo_blockstack;
00102 
00103     /** Local attributes dict (non-fast locals) */
00104     pPmDict_t fo_attrs;
00105 
00106     /** Global attributes dict (pts to root frame's globals */
00107     pPmDict_t fo_globals;
00108 
00109     /** Points to next empty slot in fo_locals (1 past TOS) */
00110     pPmObj_t *fo_sp;
00111 
00112     /** Frame can be an import-frame that handles RETURN differently */
00113     uint8_t fo_isImport:1;
00114 
00115 #ifdef HAVE_CLASSES
00116     /** Flag to indicate class initailzer frame; handle RETURN differently */
00117     uint8_t fo_isInit:1;
00118 #endif /* HAVE_CLASSES */
00119 
00120     /** Array of local vars and stack (space appended at alloc) */
00121     pPmObj_t fo_locals[1];
00122     /* WARNING: Do not put new fields below fo_locals */
00123 } PmFrame_t,
00124  *pPmFrame_t;
00125 
00126 
00127 /**
00128  * Native Frame
00129  *
00130  * A struct that holds the execution frame of a native function,
00131  * including the args and single stack slot, and pointer to the code object.
00132  *
00133  * This struct doesn't need an OD because it is only used statically in the
00134  * globals struct.  There's only one native frame, the global one.
00135  * This happens because a native function is a leaf node
00136  * in the call tree (a native func can't call python funcs).
00137  */
00138 typedef struct PmNativeFrame_s
00139 {
00140     /** Object descriptor */
00141     PmObjDesc_t od;
00142 
00143     /** Ptr to previous frame obj */
00144     struct PmFrame_s *nf_back;
00145 
00146     /** Ptr to fxn obj */
00147     pPmFunc_t nf_func;
00148 
00149     /** Single stack slot */
00150     pPmObj_t nf_stack;
00151 
00152     /** Boolean to indicate if the native frame is active */
00153     uint8_t nf_active;
00154 
00155     /** Number of args passed to the native function */
00156     uint8_t nf_numlocals;
00157 
00158     /** Local vars */
00159     pPmObj_t nf_locals[NATIVE_MAX_NUM_LOCALS];
00160 } PmNativeFrame_t,
00161  *pPmNativeFrame_t;
00162 
00163 
00164 /**
00165  * Allocate space for a new frame, fill its fields
00166  * with respect to the given function object.
00167  * Return pointer to the new frame.
00168  *
00169  * @param   pfunc ptr to Function object.
00170  * @param   r_pobj Return value; the new frame.
00171  * @return  Return status.
00172  */
00173 PmReturn_t frame_new(pPmObj_t pfunc, pPmObj_t *r_pobj);
00174 
00175 #endif /* __FRAME_H__ */