The World of Computer Software/World_Of_Computer_Software-02-386-Vol-2of3.iso/b/bc3.zip/XMEM.CPP

C/C++ Source or Header | 1992-02-14 | 4KB | 201 lines

// (C) Copyright 1992 Qualitas, Inc.  All rights reserved.
//
// xmem.cpp - example usage of memory classes in DPMI class library
//

#include <iostream.h>
#include <iomanip.h>
#include "dpmihost.h"
#include "segment.h"

//
// Function to output AbstractSegment and derived classes
//
ostream& operator << (ostream& str, AbstractSegment& s)
{
    void far *p=s.ptrTo();

    str.fill('0');
    str << "Segment: selector=" << setw(4) << hex << FP_SEG(p);
    str << " Base=" << setw(8) << s.segmentBase();
    str << " Size=" << setw(8) << s.segmentSize();

    if (s.queryProp(present))
        str << " present";
    else
        str << " not present";

    if (s.queryProp(executable))
    {
        str << " code";
        if (s.queryProp(readable))
            str << " readable";
        else
            str << " execute_only";
    }
    else
    {
        str << " data";
        if (s.queryProp(readable))
            str << " writable";
        else
            str << " read_only";
    }


    if (s.queryProp(big))
        str << " big";


    if (s.queryProp(expandDown))
        str << " expand_down";


    str << "\n";
    return str;
}


#define MAXMEMSEG 512
//
// This function illustrates the use of the MemorySegment class for
// allocating 64 KB blocks of memory from DPMI.
//
void AllocateMemory(void)
{
    int i;
    uLong totmem;

    // declare an array of pointers to MemorySegment
    MemorySegment* pMemSegs[MAXMEMSEG];

    cout << "Memory Allocation Test\n";

    for (i=0, totmem=0; i < MAXMEMSEG ; i++)
    {
        // allocate a new 64 KB MemorySegment (arg==0 means 64 KB)
        pMemSegs[i] = new MemorySegment(0);

        // if the pointer to the segment is zero,the allocation failed
        if (pMemSegs[i]->ptrTo() == 0)
            break;
        else
        {    //output the segment information
            cout << *pMemSegs[i];

            totmem += 0x10000;    // tally total memory alloc'ed
        }
    }
    cout << "Total Memory Allocated: " << dec << totmem << " bytes\n";

    // free the MemorySegments - releases memory to DPMI host
    for (--i; i >= 0; i--)
        delete pMemSegs[i];
}


//
// This function illustrates the use of the Segment class for creating
// a window on an arbitrary region of the linear address space.
//
void PeekMemory(void)
{
    Segment s;                // create a segment
    uChar far *pSeg = (uChar far *)s.ptrTo();//   and a pointer to it
    s.resize(0x80);                // set its size to 128 bytes

    uLong linearAddress;            // address to examine

    while (1)
    {
        cout << "\nEnter linear address to examine (0 to end): ";
        cin >> hex >> linearAddress;

        if (linearAddress == 0)
            break;

        s.move(linearAddress);        // position the segment

        int i=0;
        do                // display segment data
        {
            cout << hex << setw(2) << (int)pSeg[i] << " ";
            i++;
            if ((i % 16) == 0) cout << "\n";

        } while (i < 128);
        cout << "\n";
    };
}


void ShowProperties(void)
{
    Segment s;
    cout << "\nTest Segment Properties\n";
    cout << " Default properties:\n " << s;

    s-present;
    cout << " Make it not present:\n " << s;

    s+executable;
    cout << " Make it a code segment:\n " << s;

    s-executable; s+present; s-writable;
    cout << " Make it present read-only data:\n " << s;
}

//
// This function illustrates other members and derived classes of
// AbstractSegment
//
void ShowMisc(void)
{
    // DOSMemory class allocates memory from DOS

    cout << "\nTest other memory classes\n";

    DOSMemory d(0x10);        // create a 0x10 paragraph block
    cout << " A 0x10 paragraph DOSMemory block:\n " << d;

    // Resize it to 8 paragraphs
    d.resize(8);
    cout << " DOSMemory block resized to 8 paragraphs:\n " << d;

    // Create an alias to this using an alternate Segment constructor

    Segment aliasToDOSMemory(d); aliasToDOSMemory+executable;
    cout << " A code alias to that segment:\n " << aliasToDOSMemory;

    // Create a specific descriptor

    Segment specific(0xf);
    cout << " Specific descriptor 0xFh:\n " << specific;

    // Create a CommonRealSegment at paragraph 0xb800

    CommonRealSegment crs(0xb800);
    cout << " A common real segment at paragraph 0xb800:\n " << crs;

    // Create a Huge Segment that maps the low megabyte:

    HugeSegment h(0x100000); h.move(0);
    cout << " A huge segment spanning the low 1 MB:\n " << h;
}


void main(void)
{
    DPMIhost dpmi;

    if (dpmi.getStatus() == DPMIok)
    {
        dpmi.enterProtectedMode();
        AllocateMemory();
        PeekMemory();
        ShowProperties();
        ShowMisc();
    }
    else
        cout << "DPMI host not present\n";
}