/* backgrnd.c - True Flash File System *//* Copyright 1984-2004 Wind River Systems, Inc. */#include "copyright_wrs.h"/* FAT-FTL Lite Software Development Kit * Copyright (C) M-Systems Ltd. 1995-1997	*//*modification history--------------------01a,29jul04,alr  modified file header, restarted history*/                 #include "flsocket.h"#include "backgrnd.h"#ifdef BACKGROUND#include <setjmp.h>#include <dos.h>static void (*backgroundTask)(void *);typedef struct {  jmp_buf	registers;  unsigned	mappingContext;  void *	object;  FLSocket *	socket;} Context;static Context foregroundContext, backgroundContext, *currentContext;static int switchContext(Context *toContext, int sendValue){  int state;  if (toContext == currentContext)    return 0;  state = setjmp(currentContext->registers);	/* save our state */  if (state == 0) {    if (backgroundContext.socket) {      currentContext->mappingContext = flGetMappingContext(backgroundContext.socket);      if (toContext->mappingContext != UNDEFINED_MAPPING)	flMap(backgroundContext.socket,(CardAddress) toContext->mappingContext << 12);    }    currentContext = toContext;    longjmp(toContext->registers,sendValue);  }  /* We are back here when target task suspends, and 'state'     is the 'sendValue' on suspend */  return state;}int flForeground(int sendValue){  return switchContext(&foregroundContext,sendValue);}int flBackground(int sendValue){  return switchContext(&backgroundContext,sendValue);}static char backgroundStack[200];int flStartBackground(unsigned volNo, void (*routine)(void *), void *object){  if (currentContext != &foregroundContext)    return 0;  while (backgroundTask)		/* already exists */    flBackground(BG_RESUME);		/* run it until it finishes */  backgroundTask = routine;  backgroundContext.object = object;  backgroundContext.socket = flSocketOf(volNo);  flNeedVcc(backgroundContext.socket);  return flBackground(BG_RESUME);}void flCreateBackground(void){  FLMutex dummyMutex;  foregroundContext.socket = backgroundContext.socket = NULL;  if (setjmp(foregroundContext.registers) != 0)    return;#ifdef __WIN32__   _ESP = (void *) (backgroundStack + sizeof backgroundStack);#else  flStartCriticalSection(&dummyMutex);  _SP = FP_OFF((void far *) (backgroundStack + sizeof backgroundStack));  _SS = FP_SEG((void far *) (backgroundStack + sizeof backgroundStack));  flEndCriticalSection(&dummyMutex);#endif  backgroundTask = NULL;  if (setjmp(backgroundContext.registers) == 0) {    currentContext = &foregroundContext;    longjmp(foregroundContext.registers,1);       /* restore stack and continue */  }  /* We are back here with our new stack when 'background' is called */  for (;;) {    if (backgroundTask) {      (*backgroundTask)(backgroundContext.object);      flDontNeedVcc(backgroundContext.socket);      backgroundTask = NULL;    }    flForeground(-1);  }}#endif