rfreelist.nc

nesC写的heed算法

// $Id: RFreeList.nc,v 1.1.4.2 2003/08/18 22:09:47 cssharp Exp $

/*									tab:4
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 * Copyright (c) 2002-2003 Intel Corporation
 * All rights reserved.
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// A free list for read-only filing systems
includes IFS;
module RFreeList {
  provides {
    interface StdControl;
    interface IFileFree;
  }
#include "massert.h"
}
implementation {
  fileblock_t nFreeBlocks, freePtr, reserved;

  command result_t StdControl.init() {
    call IFileFree.freeall();
    return SUCCESS;
  }

  command result_t StdControl.start() {
    return SUCCESS;
  }

  command result_t StdControl.stop() {
    return SUCCESS;
  }

  command void IFileFree.freeall() {
    nFreeBlocks = IFS_NUM_PAGES;
    reserved = 0;
  }

  command fileblock_t IFileFree.nFreeBlocks() {
    return nFreeBlocks - reserved;
  }

  command void IFileFree.setReserved(fileblock_t n) {
    assert(n <= nFreeBlocks);
    reserved = n;
  }

  command fileblock_t IFileFree.allocate() {
    return 0;
  }

  command void IFileFree.free(fileblock_t n) {
    // Should never be called
  }

  command void IFileFree.setFreePtr(fileblock_t n) {
    assert(n < IFS_NUM_PAGES);
    freePtr = n;
  }

  command void IFileFree.reserve(fileblock_t n) {
    nFreeBlocks--;
  }

  command bool IFileFree.inuse(fileblock_t n) {
    // We say everything is free to keep ScanFS happy
    return n >= IFS_NUM_PAGES;
  }
}