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LibrePilot/flight/libraries/PyMite/vm/frame.h

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/*
# This file is Copyright 2003, 2006, 2007, 2009, 2010 Dean Hall.
#
# This file is part of the PyMite VM.
# The PyMite VM is free software: you can redistribute it and/or modify
# it under the terms of the GNU GENERAL PUBLIC LICENSE Version 2.
#
# The PyMite VM is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# A copy of the GNU GENERAL PUBLIC LICENSE Version 2
# is seen in the file COPYING in this directory.
*/
#ifndef __FRAME_H__
#define __FRAME_H__
/**
* \file
* \brief VM Frame
*
* VM frame header.
*/
/**
* The maximum number of local variables a native function can have.
* This defines the length of the locals array in the native frame struct.
*/
#define NATIVE_MAX_NUM_LOCALS 8
/**
* Block Type
*
* Numerical values to put in the 'b_type' field of the tPmBlockType struct.
*/
typedef enum PmBlockType_e
{
/** Invalid block type */
B_INVALID = 0,
/** Loop type */
B_LOOP,
/** Try type */
B_TRY
} PmBlockType_t, *pPmBlockType_t;
/**
* Block
*
* Extra info for loops and trys (others?)
* Frames use linked list of blocks to handle
* nested loops and try-catch blocks.
*/
typedef struct PmBlock_s
{
/** Obligatory obj descriptor */
PmObjDesc_t od;
/** Ptr to backup stack ptr */
pPmObj_t *b_sp;
/** Handler fxn obj */
uint8_t const *b_handler;
/** Block type */
PmBlockType_t b_type:8;
/** Next block in stack */
struct PmBlock_s *next;
} PmBlock_t,
*pPmBlock_t;
/**
* Frame
*
* A struct that holds the execution frame of a function, including the stack,
* local vars and pointer to the code object.
*
* This struct doesn't declare the stack.
* frame_new() is responsible for allocating the extra memory
* at the tail of fo_locals[] to hold both the locals and stack.
*/
typedef struct PmFrame_s
{
/** Obligatory obj descriptor */
PmObjDesc_t od;
/** Ptr to previous frame obj */
struct PmFrame_s *fo_back;
/** Ptr to fxn obj */
pPmFunc_t fo_func;
/** Mem space where func's CO comes from */
PmMemSpace_t fo_memspace:8;
/** Instrxn ptr (pts into memspace) */
uint8_t const *fo_ip;
/** Linked list of blocks */
pPmBlock_t fo_blockstack;
/** Local attributes dict (non-fast locals) */
pPmDict_t fo_attrs;
/** Global attributes dict (pts to root frame's globals */
pPmDict_t fo_globals;
/** Points to next empty slot in fo_locals (1 past TOS) */
pPmObj_t *fo_sp;
/** Frame can be an import-frame that handles RETURN differently */
uint8_t fo_isImport:1;
#ifdef HAVE_CLASSES
/** Flag to indicate class initailzer frame; handle RETURN differently */
uint8_t fo_isInit:1;
#endif /* HAVE_CLASSES */
/** Array of local vars and stack (space appended at alloc) */
pPmObj_t fo_locals[1];
/* WARNING: Do not put new fields below fo_locals */
} PmFrame_t,
*pPmFrame_t;
/**
* Native Frame
*
* A struct that holds the execution frame of a native function,
* including the args and single stack slot, and pointer to the code object.
*
* This struct doesn't need an OD because it is only used statically in the
* globals struct. There's only one native frame, the global one.
* This happens because a native function is a leaf node
* in the call tree (a native func can't call python funcs).
*/
typedef struct PmNativeFrame_s
{
/** Object descriptor */
PmObjDesc_t od;
/** Ptr to previous frame obj */
struct PmFrame_s *nf_back;
/** Ptr to fxn obj */
pPmFunc_t nf_func;
/** Single stack slot */
pPmObj_t nf_stack;
/** Boolean to indicate if the native frame is active */
uint8_t nf_active;
/** Number of args passed to the native function */
uint8_t nf_numlocals;
/** Local vars */
pPmObj_t nf_locals[NATIVE_MAX_NUM_LOCALS];
} PmNativeFrame_t,
*pPmNativeFrame_t;
/**
* Allocate space for a new frame, fill its fields
* with respect to the given function object.
* Return pointer to the new frame.
*
* @param pfunc ptr to Function object.
* @param r_pobj Return value; the new frame.
* @return Return status.
*/
PmReturn_t frame_new(pPmObj_t pfunc, pPmObj_t *r_pobj);
#endif /* __FRAME_H__ */