alloc-address.cc

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/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1997 Regents of the University of California.
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 *    must display the following acknowledgement:
 *  This product includes software developed by the Daedalus Research
 *  Group at the University of California Berkeley.
 * 4. Neither the name of the University nor of the Research Group may be
 *    used to endorse or promote products derived from this software without
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 * $Header: /nfs/jade/vint/CVSROOT/ns-2/routing/alloc-address.cc,v 1.10 2000/09/14 18:19:25 haoboy Exp $
 */

/* functions invoked to allocate bits to the ns-address space */

#include <stdlib.h>
#include <assert.h>
#include "config.h"
#include <tclcl.h>


class AllocAddr : public TclObject {
public:
    AllocAddr();
    ~AllocAddr();
    int command(int argc, const char*const* argv);
protected:
    void get_mask(nsmask_t *mask, int fieldsize);
    void alloc(int n);
    bool check_size(int n);
    bool find_free(int len, int *pos);
    bool test(int which);
    void set_field(int offset, int len, nsmask_t *mask, int *shift);
    void free_field(int len);
    void mark(int i);
    int size_;
    int *bitmap_;
};


class AllocAddrClass : public TclClass {
public:
    AllocAddrClass() : TclClass("AllocAddr") {}
    TclObject* create(int, const char*const*) {
        return (new AllocAddr());
    }
} AllocAddr_class;



int AllocAddr::command(int argc, const char*const* argv)
{
    int offset,
        addrsize,
        shift,
        fieldlen;
    nsmask_t mask;

    Tcl& tcl = Tcl::instance();

    if (argc == 3) {
        if (strcmp(argv[1], "freebit") == 0) {
            fieldlen = atoi(argv[2]);
            assert(fieldlen > 0);
            free_field(fieldlen);
            return (TCL_OK);
        }
    }


    else if (argc == 4) {
        if (strcmp(argv[1], "setbit") == 0) {
            fieldlen = atoi(argv[2]);
            addrsize = atoi(argv[3]);
            if (!check_size(addrsize)) {
                tcl.result("setbit: Size_ increased: Reallocate bits");
                return (TCL_ERROR);
            }
            if (!find_free(fieldlen, &offset)) {
                tcl.result("setbit: no contiguous space found\n");
                return (TCL_ERROR);
            }
            set_field(offset, fieldlen, &mask, &shift);
            // TESTING
            tcl.resultf("%d %d", mask, shift);
            return (TCL_OK);
        }
    }
    else if (argc == 5) {
        int oldfldlen;
        if (strcmp(argv[1], "expand-port") == 0) {
            fieldlen = atoi(argv[2]);
            addrsize = atoi(argv[3]);
            oldfldlen = atoi(argv[4]);
            if (!check_size(addrsize)) {
                tcl.result("expand-port: Size_ increased: Reallocate bits");
                return (TCL_ERROR);
            }
            if (!find_free(fieldlen, &offset)) {
                tcl.result("expand-port: no contiguous space found\n");
                return (TCL_ERROR);
            }
            int i, k;
            for (i = offset, k = 0; k < fieldlen; k++, i--) {
                bitmap_[i] = 1;
            }
            shift = offset - (fieldlen - 1);
            get_mask(&mask, fieldlen + oldfldlen);
            // TESTING
            tcl.resultf("%d %d", mask, shift);
            return (TCL_OK);
        }
    }
    return TclObject::command(argc, argv);
}


AllocAddr::AllocAddr()
{
    size_ = 0;
    bitmap_ = 0;

}

AllocAddr::~AllocAddr()
{
    delete [] bitmap_;

}

void AllocAddr::alloc(int n)
{
    size_ = n;
    bitmap_ = new int[n];
    for (int i=0; i < n; i++)
        bitmap_[i] = 0;
}


bool AllocAddr::check_size(int n)
{
    if (n <= size_)
        return 1;
    assert (n > 0);
    if (size_ == 0) {
        alloc(n);
        return 1;
    }
    if (n > size_) 
        return 0;
    return 1;

    // this check is no longer needed, as now bits are re-allocated every time
    // the size changes.
    //     int *old = bitmap_;
    //     int osize = size_;
    //     alloc(n);
    //     for (int i = 0; i < osize; i++) 
    //  bitmap_[i] = old[i];
    //     delete [] old;
}

void AllocAddr::mark(int i)
{
    bitmap_[i] = 1;
}


void AllocAddr::get_mask(nsmask_t *mask, int fieldsize)
{
    // int temp = (int)(pow(2, (double)fieldsize));
    *mask = (1 << fieldsize) - 1;
}


bool AllocAddr::test(int which)
{
    assert(which <= size_);
    if (bitmap_[which] == 1)
        return TRUE;
    else
        return FALSE;
}


bool AllocAddr::find_free(int len, int *pos) 
{
    int count = 0;
    int temp = 0;

    for (int i = (size_ - 1); i >= 0; i--)
        if (!test(i)) {
            /**** check if n contiguous bits are free ****/
            temp = i;
            for (int k = 0; (k < len) && (i >=0); k++, i--){
                if(test(i)) {
                    count = 0;
                    break;
                }
                count++;
            }
            if (count == len) {
                *pos = temp;
                return 1;
            }
        }
    return 0;
}


void AllocAddr::set_field(int offset, int len, nsmask_t *mask, int *shift)
{
    int i, k;

    for (k = 0, i = offset; k < len; k++, i--) {
        bitmap_[i] = 1; 
    }
    *shift = offset - (len-1);
    get_mask(mask, len);
}


void AllocAddr::free_field(int len)
{
    int count = 0;

    for (int i = 0; i < size_; i++) {
        if (test(i)) {
            bitmap_[i] = 0;
            count++;
        }
        if (count == len)
            break;
    }
}

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