296 lines
9.6 KiB
C
296 lines
9.6 KiB
C
/*
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* $Id$
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*/
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/*
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* Harbour Project source code:
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* Codeblock runtime support
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*
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* Copyright 1999 Ryszard Glab <rglab@imid.med.pl>
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* www - http://www.harbour-project.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version, with one exception:
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*
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* The exception is that if you link the Harbour Runtime Library (HRL)
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* and/or the Harbour Virtual Machine (HVM) with other files to produce
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* an executable, this does not by itself cause the resulting executable
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* to be covered by the GNU General Public License. Your use of that
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* executable is in no way restricted on account of linking the HRL
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* and/or HVM code into it.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA (or visit
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* their web site at http://www.gnu.org/).
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*
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*/
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/* The Harbour implementation of codeblocks */
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#include "extend.h"
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#include "ctoharb.h"
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#include "itemapi.h"
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/* Creates the codeblock structure
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*
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* pBuffer -> the buffer with pcodes (without HB_P_PUSHBLOCK)
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* wLocals -> number of local variables referenced in a codeblock
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* pLocalPosTable -> a table with positions on eval stack for referenced variables
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* pSymbols -> a pointer to the module symbol table
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*
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* Note: pLocalPosTable cannot be used if uiLocals is ZERO
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*
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*/
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HB_CODEBLOCK_PTR hb_codeblockNew( BYTE * pBuffer,
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USHORT uiLocals,
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USHORT * pLocalPosTable,
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PHB_SYMB pSymbols )
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{
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HB_CODEBLOCK_PTR pCBlock;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockNew(%p, %hu, %p, %p)", pBuffer, uiLocals, pLocalPosTable, pSymbols));
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pCBlock = ( HB_CODEBLOCK_PTR ) hb_xgrab( sizeof( HB_CODEBLOCK ) );
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/* Store the number of referenced local variables
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*/
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pCBlock->uiLocals = uiLocals;
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if( uiLocals )
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{
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/* NOTE: if a codeblock will be created by macro compiler then
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* uiLocal have to be ZERO
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* uiLocal will be also ZERO if it is a nested codeblock
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*/
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USHORT ui = 1;
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PHB_ITEM pLocal;
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HB_HANDLE hMemvar;
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/* Create a table that will store the values of local variables
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* accessed in a codeblock
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* The element 0 is used as the counter of references to this table
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*/
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pCBlock->pLocals = ( PHB_ITEM ) hb_xgrab( ( uiLocals + 1 ) * sizeof( HB_ITEM ) );
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pCBlock->pLocals[ 0 ].type = IT_LONG;
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pCBlock->pLocals[ 0 ].item.asLong.value = 1;
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while( uiLocals-- )
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{
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/* Swap the current value of local variable with the reference to this
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* value.
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* TODO: If Harbour will support threads in the future then we need
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* to implement some kind of semaphores here.
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*/
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pLocal = hb_stack.pBase + 1 + ( *pLocalPosTable++ );
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if( ! IS_MEMVAR( pLocal ) )
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{
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/* Change the value only if this variable is not referenced
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* by another codeblock yet.
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* In this case we have to copy the current value to a global memory
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* pool so it can be shared by codeblocks
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*/
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hMemvar = hb_memvarValueNew( pLocal, FALSE );
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pLocal->type = IT_BYREF | IT_MEMVAR;
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pLocal->item.asMemvar.itemsbase = hb_memvarValueBaseAddress();
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pLocal->item.asMemvar.offset = 0;
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pLocal->item.asMemvar.value = hMemvar;
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hb_memvarValueIncRef( pLocal->item.asMemvar.value );
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memcpy( pCBlock->pLocals + ui, pLocal, sizeof( HB_ITEM ) );
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}
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else
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{
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/* This variable is already detached (by another codeblock)
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* - copy the reference to a value
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*/
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/* Increment the reference counter so this value will not be
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* released if other codeblock will be deleted
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*/
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hb_memvarValueIncRef( pLocal->item.asMemvar.value );
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memcpy( pCBlock->pLocals + ui, pLocal, sizeof( HB_ITEM ) );
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}
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++ui;
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}
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}
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else
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{
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/* Check if this codeblock is created during evaluation of another
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* codeblock - all inner codeblocks use the local variables table
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* created during creation of the outermost codeblock
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*/
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PHB_ITEM pLocal;
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pLocal = hb_stack.pBase + 1;
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if( IS_BLOCK( pLocal ) )
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{
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HB_CODEBLOCK_PTR pOwner = pLocal->item.asBlock.value;
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pCBlock->pLocals = pOwner->pLocals;
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pCBlock->uiLocals = uiLocals = pOwner->uiLocals;
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if( pOwner->pLocals )
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{ /* the outer codeblock have the table with local references - reuse it */
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while( uiLocals )
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{
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hb_memvarValueIncRef( pCBlock->pLocals[ uiLocals ].item.asMemvar.value );
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--uiLocals;
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}
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/* increment a reference counter for the table of local references
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*/
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pCBlock->pLocals[ 0 ].item.asLong.value++;
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}
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}
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else
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pCBlock->pLocals = NULL;
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}
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/*
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* The codeblock pcode is stored in static segment.
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* The only allowed operation on a codeblock is evaluating it then
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* there is no need to duplicate its pcode - just store the pointer to it
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*/
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pCBlock->pCode = pBuffer;
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pCBlock->dynBuffer = FALSE;
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pCBlock->pSymbols = pSymbols;
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pCBlock->ulCounter = 1;
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HB_TRACE(HB_TR_INFO, ("codeblock created (%li) %lx", pCBlock->ulCounter, pCBlock));
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return pCBlock;
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}
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HB_CODEBLOCK_PTR hb_codeblockMacroNew( BYTE * pBuffer, USHORT usLen )
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{
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HB_CODEBLOCK_PTR pCBlock;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockMacroNew(%p, %i)", pBuffer, usLen));
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pCBlock = ( HB_CODEBLOCK_PTR ) hb_xgrab( sizeof( HB_CODEBLOCK ) );
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/* Store the number of referenced local variables
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*/
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pCBlock->uiLocals = 0;
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pCBlock->pLocals = NULL;
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/*
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* The codeblock pcode is stored in dynamically allocated memory that
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* can be deallocated after creation of a codeblock. We have to duplicate
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* the passed buffer
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*/
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pCBlock->pCode = ( BYTE * ) hb_xgrab( usLen );
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memcpy( pCBlock->pCode, pBuffer, usLen );
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pCBlock->dynBuffer = TRUE;
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pCBlock->pSymbols = NULL; /* macro-compiled codeblock cannot acces a local symbol table */
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pCBlock->ulCounter = 1;
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HB_TRACE(HB_TR_INFO, ("codeblock created (%li) %lx", pCBlock->ulCounter, pCBlock));
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return pCBlock;
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}
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/* Delete a codeblock
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*/
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void hb_codeblockDelete( HB_ITEM_PTR pItem )
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{
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HB_CODEBLOCK_PTR pCBlock = pItem->item.asBlock.value;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockDelete(%p)", pItem));
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HB_TRACE(HB_TR_INFO, ("deleting a codeblock (%li) %lx", pCBlock->ulCounter, pCBlock));
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if( --pCBlock->ulCounter == 0 )
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{
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/* free space allocated for local variables
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*/
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if( pCBlock->pLocals )
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{
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USHORT ui = 1;
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while( ui <= pCBlock->uiLocals )
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{
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hb_memvarValueDecRef( pCBlock->pLocals[ ui ].item.asMemvar.value );
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++ui;
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}
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/* decrement the table reference counter and release memory if
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* it was the last reference
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*/
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if( --pCBlock->pLocals[ 0 ].item.asLong.value == 0 )
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hb_xfree( pCBlock->pLocals );
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}
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/* free space allocated for pcodes - if it was macro-compiled codeblock
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*/
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if( pCBlock->dynBuffer )
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hb_xfree( pCBlock->pCode );
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/* free space allocated for a CODEBLOCK structure
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*/
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hb_xfree( pCBlock );
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HB_TRACE(HB_TR_INFO, ("codeblock deleted (%li) %lx", pCBlock->ulCounter, pCBlock));
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}
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}
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/* Evaluate passed codeblock
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* Before evaluation we have to switch to a static variable base that
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* was defined when the codeblock was created.
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* (The codeblock can only see the static variables defined in a module
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* where the codeblock was created)
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*/
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void hb_codeblockEvaluate( HB_ITEM_PTR pItem )
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{
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int iStatics = hb_stack.iStatics;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockEvaluate(%p)", pItem));
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hb_stack.iStatics = pItem->item.asBlock.statics;
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hb_vmExecute( pItem->item.asBlock.value->pCode, pItem->item.asBlock.value->pSymbols );
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hb_stack.iStatics = iStatics;
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}
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/* Get local variable referenced in a codeblock
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*/
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PHB_ITEM hb_codeblockGetVar( PHB_ITEM pItem, LONG iItemPos )
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{
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HB_CODEBLOCK_PTR pCBlock = pItem->item.asBlock.value;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockGetVar(%p, %ld)", pItem, iItemPos));
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/* local variables accessed in a codeblock are always stored as reference */
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return hb_itemUnRef( pCBlock->pLocals - iItemPos );
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}
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/* Get local variable passed by reference
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*/
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PHB_ITEM hb_codeblockGetRef( PHB_ITEM pItem, PHB_ITEM pRefer )
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{
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HB_CODEBLOCK_PTR pCBlock = pItem->item.asBlock.value;
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockGetRef(%p, %p)", pItem, pRefer));
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return pCBlock->pLocals - pRefer->item.asRefer.value;
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}
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/* Copy the codeblock
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* TODO: check if such simple pointer coping will allow to evaluate
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* codeblocks recursively
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*/
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void hb_codeblockCopy( PHB_ITEM pDest, PHB_ITEM pSource )
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{
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HB_TRACE(HB_TR_DEBUG, ("hb_codeblockCopy(%p, %p)", pDest, pSource));
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pDest->item.asBlock.value = pSource->item.asBlock.value;
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pDest->item.asBlock.value->ulCounter++;
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HB_TRACE(HB_TR_INFO, ("copied a codeblock (%li) %lx", pSource->item.asBlock.value->ulCounter, pSource->item.asBlock.value));
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}
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