brk

/*
** This is the only file that will be uploaded to the testing server for grading.
** Please put your implementation of the tasks in here.
** In order to configure the simulated memory hardware to satisfy the requests
** use the Kernel::mmu member through its interface.
** Although you cannot change the definitions in the Kernel class you can declare
** procedures in this file for any code that you want to write (and if you pass
** "this" to these procedures then you can access the Kernel members and methods.
*/

#include "base/system.h"
#include <iostream>
using namespace std;

uint32_t heapStart=0x00200000;
uint32_t frameSize=1024*4; //4096

//change non-zero values to zero
uint32_t sizeAllocated=0;

void Kernel::syscall(int num, uint32_t arg0, uint32_t arg1, uint32_t arg2, uint32_t arg3)
{
    printf("output: syscall %d arg0=%08x arg1=%08x arg2=%08x arg3=%08x\n", num, arg0, arg1, arg2, arg3);

    switch(num)
    {
        case SYS_BRK:
            {
                //std::cout << "Brk is not implemented" << std::endl;
                heapStart= userModeHeap.base;
                //uint32_t size=arg0; //arg0 is size
                if(arg0>sizeAllocated)
                {
                    //increase
                    cout<<" - Increase - "<<endl;
                    for(uint32_t i=heapStart;i<heapStart+arg0;i+=4096)
                    {
                        uint32_t loc = (i>>12UL)&0x3ffUL;
                        uint32_t tableID = i>>22UL;
                        if(mmu.cr3.tables[tableID]==NULL)
                        {
                            cout<<"- Creating table - "<<endl;
                            mmu.cr3.tables[tableID]= new PageTable;
                            //std::cin.get();
                        }
                        //uint32_t loc= ((heapStart+((i)*frameSize))>>12UL)&0x3ffUL;
                        mmu.cr3.tables[tableID]->entries[loc].frame = allocateFrame();
                        mmu.cr3.tables[tableID]->entries[loc].present = true;
                    }
                }
                else if(arg0<=sizeAllocated)
                {
                    //decrease
                    cout<<" - Decrease - "<<endl;
                    for(uint32_t i=heapStart+sizeAllocated;i>=heapStart+arg0;i-=4096)
                    {
                        uint32_t loc = (i>>12UL)&0x3ffUL;
                        uint32_t tableID = i>>22UL;
                        freeFrame(mmu.cr3.tables[tableID]->entries[loc].frame);
                        mmu.cr3.tables[tableID]->entries[loc].frame = 0;
                        mmu.cr3.tables[tableID]->entries[loc].present = false;
                    }
                }
                sizeAllocated = arg0;
            }
            return;
        default:
            std::cout << "Unrecognised syscall: " << num << std::endl;
            return;
    }
}


void Kernel::pageFaultHandler(uint32_t vaddr)
{
    printf("output: Page fault! addr=%08x\n",vaddr);
    uint32_t stack =userModeStack.base;

    cout<<hex<<stack<<dec<<endl;
    //syscall(2,0,0,0,0);
    //printf("Success! addr=%08x\n",vaddr);
    throw std::string("output: Program segv");
}