/*
** 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"

void Kernel::syscall(int num, uint32_t arg0, uint32_t arg1, uint32_t arg2, uint32_t arg3)
{
    uint32_t numFrame, currSize, numDir, lastIndex;
    uint32_t PT1, PT2, freeThis;



    printf("output: syscall %d arg0=%08x arg1=%08x arg2=%08x arg3=%08x\n", num, arg0, arg1, arg2, arg3);
    switch(num) {
        case SYS_BRK:

            currSize = 0;

            numFrame = arg0/4096;

            numDir =  (numFrame/1024)+1;

            PT1 = userModeHeap.base>>22;
            PT2 = (userModeHeap.base>>12)&0x3ff;

            for(int k = PT1; k<numDir; k++){
              if(this -> mmu.cr3.tables[k] == NULL){
                this -> mmu.cr3.tables[k] = new PageTable();
              }

              if(k == PT1){
                for (int i = PT2; i < 1024; i++) {
                  if(this -> mmu.cr3.tables[k]->entries[i].present == false){
                    this -> mmu.cr3.tables[k]->entries[i].frame = allocateFrame();
                    this -> mmu.cr3.tables[k]->entries[i].present = true;
                  }
                  currSize++;
                  if(currSize == numFrame){
                    lastIndex = i;
                    i=1024;
                  }
                }
              }
              else{
                for (int i = 0; i < 1024; i++) {
                  if(this -> mmu.cr3.tables[k]->entries[i].present == false){
                    this -> mmu.cr3.tables[k]->entries[i].frame = allocateFrame();
                    this -> mmu.cr3.tables[k]->entries[i].present = true;
                  }
                  currSize++;
                  if(currSize == numFrame){
                    lastIndex = i;
                    i=1024;
                  }
                }
              }
            }

            lastIndex++;

            for(int k = (numDir-1); k < 1024; k++)
            {
              if(k == (numDir-1)){
                for (int i = lastIndex; i < 1024; i++) {
                  //printf("%d\n", i);
                  //printf("%d\n", (numFrame+PT2));
                  if(this -> mmu.cr3.tables[k] -> entries[i].present == true){
                    freeThis = this -> mmu.cr3.tables[k]->entries[i].frame;
                    freeFrame(freeThis);
                    this -> mmu.cr3.tables[k]->entries[i].frame = 0;
                    this -> mmu.cr3.tables[k]->entries[i].present = false;
                  }
                }
              }
              else{
                for (int i = 0; i < 1024; i++) {

                  //printf("%d\n", (numFrame+PT2));
                  if(this -> mmu.cr3.tables[k] != NULL){
                    if(this -> mmu.cr3.tables[k] -> entries[i].present == true){
                      freeThis = this -> mmu.cr3.tables[k]->entries[i].frame;
                      freeFrame(freeThis);
                      this -> mmu.cr3.tables[k]->entries[i].frame = 0;
                      this -> mmu.cr3.tables[k]->entries[i].present = false;
                    }
                  }
                }
              }

            }

            return;
        default:
            std::cout << "Unrecognised syscall: " << num << std::endl;
            return;
  }

}


void Kernel::pageFaultHandler(uint32_t vaddr)
{
    printf("output: Page fault! addr=%08x\n",vaddr);
    throw std::string("output: Program segv");
}