/**************************************************************************************
 Copyright (c) 2002
      The UbixOS Project

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 $Id: paging.c,v 1.24 2003/04/24 00:16:30 reddawg Exp $
**************************************************************************************/

#include <vmm/paging.h>
#include <vmm/memory.h>
#include <sys/idt.h>
#include <sys/gdt.h>
#include <ubixos/types.h>
#include <ubixos/schedule.h>
#include <ubixos/panic.h>
#include <lib/kmalloc.h>


uLong *pageDirectory = 0x0;
uLong memoryStart = 0x100000;
uLong *kernelPageDirectory = 0x0;

/************************************************************************

Function: void initPageSystem()
Description: This Function Will Initialize The Ubix Paging Sytem
Notes:

07/29/02 - I Started The Rewrite Of This Function Hopefully All Goes Well
           This Is The Startup Routine To Build The Initial VM Space.
           Also Note I May Switch The Page Fault To A Task Gate.

07/30/02 - I Decided That To Save On Performance All Page Tables Will Be
           Mapped In At BFC00000 So That Memory Does Not Need To Be Relocated
           To Alter Page Tables.
           Also Put Page Index At 0x100000
           
************************************************************************/
void initPagingSystem() {
  int i=0,x=0;
  uLong *pageTable;
  struct tssStruct *doubleFaultTSS = (struct tssStruct *)0x4000;
  //Allocate A Page For The Kernels VM Space Page Directory
  kernelPageDirectory = (uLong *)findFreePage(_current->id);
  //Make Sure The Page Directory Is Clean
  for (i=0;i<pageEntries;i++) {
    kernelPageDirectory[i] = (uLong)0x0;
    }
  //Allocate A Page For The First 4MB Of Memory
  pageTable = (uLong *)findFreePage(_current->id);
  kernelPageDirectory[0] = (uLong)((uLong)(pageTable) | pagePresent|pageWrite|pageUser);//pageDefault);
  //Make Sure The Page Table Is Clean
  for (i=0;i<pageEntries;i++) {
    pageTable[i] = (uLong)0x0;
    }
  //Map The First 1MB Of Memory To The Kernel VM Space
  for (i=0;i<(pageEntries/4);i++) {
    if ((i*0x1000) < 0xC0000) {
      pageTable[i] = (uLong)((i*0x1000) | pagePresent|pageWrite|pageUser);// pageDefault);
      }
    else {
      pageTable[i] = (uLong)((i*0x1000) | pagePresent|pageUser);// pageDefault);
      }
    }
  //Create Page Tables For The Top 1GB Of VM Space This Is To Be Shared With All VM Spaces
  for (i=768;i<pageEntries;i++) {
    pageTable = (uLong *)findFreePage(-1);
    //Make Sure The Page Table Is Clean
    for (x=0;x<pageEntries;x++) {
      pageTable[x] = (uLong)0x0;
      }
    //Map In The Page Directory
    kernelPageDirectory[i] = (uLong)((uLong)(pageTable) | pagePresent|pageWrite|pageUser);//pageDefault);
    }
  //Set Up Memory To Be All The Allocated Page Directories
  pageTable = (uLong *)findFreePage(-1);
  kernelPageDirectory[767] = ((uLong)pageTable | pagePresent|pageWrite|pageUser);//pageDefault);
  for (i=0;i<pageEntries;i++) {
    pageTable[i] = kernelPageDirectory[i];
    }
  //Also Set Up Page Directory To Be The The First Page In 0xE0400000
  pageTable = (uLong *)(kernelPageDirectory[0] & 0xFFFFF000);
  pageTable[256] = (uLong)((uLong)(kernelPageDirectory) | pagePresent|pageWrite|pageUser);//pageDefault);
  //Now Lets Turn On Paging With This Initial Page Table
  asm(
    "movl %0,%%eax          \n"
    "movl %%eax,%%cr3       \n"
    "movl %%cr0,%%eax       \n"
    "orl  $0x80010000,%%eax \n" //Flags To Enable Paging With Protection
    "movl %%eax,%%cr0       \n"
    : : "d" ((uLong *)(kernelPageDirectory))
    );
  //Now Add The IDT Entry For Page Faults
  setVector(_pageFault,14,dPresent + dInt + dDpl3);
  //Remap The Memory List
  for (i=0x101000;i<=(0x101000+(numPages*sizeof(mMap)));i+=0x1000) {
    remapPage(i,(0xE6667000+(i-0x101000)));
    }
  memoryMap = (mMap *)0xE6667000;

  doubleFaultTSS->back_link    = 0x0;
  doubleFaultTSS->esp0         = (uInt32)kmalloc(4096,-2)+4095;
  doubleFaultTSS->ss0          = 0x10;
  doubleFaultTSS->esp1         = 0x0;
  doubleFaultTSS->ss1          = 0x0;
  doubleFaultTSS->esp2         = 0x0;
  doubleFaultTSS->ss2          = 0x0;
  doubleFaultTSS->cr3          = (unsigned int)kernelPageDirectory;
  doubleFaultTSS->eip          = (unsigned int)&doubleFault;
  doubleFaultTSS->eflags       = 0x206;
  doubleFaultTSS->esp          = 0x1BFFF;
  doubleFaultTSS->ebp          = 0x1BFFF;
  doubleFaultTSS->esi          = 0x0;
  doubleFaultTSS->edi          = 0x0;
  doubleFaultTSS->es           = 0x10;
  doubleFaultTSS->cs           = 0x08;
  doubleFaultTSS->ss           = 0x10;
  doubleFaultTSS->ds           = 0x10;
  doubleFaultTSS->fs           = 0x10;
  doubleFaultTSS->gs           = 0x10;
  doubleFaultTSS->ldt          = 0x0;
  doubleFaultTSS->trace_bitmap = 0x0000;
  doubleFaultTSS->io_map       = 0x8000;
    
  }

void *mapFromTask(pidType pid,void *ptr,uInt32 size) {
  kTask_t *child = 0x0;
  uLong i = 0x0,x = 0x0,y = 0x0,count = ((size+4095)/0x1000),c = 0x0;
  uShort dI = 0x0,tI = 0x0;
  uInt32 baseAddr = 0x0,offset = 0x0;
  uInt32 *childPageDir   = (uInt32 *)0x5A00000;
  uInt32 *childPageTable = 0x0;
  uInt32 *pageTableSrc   = 0x0;
  offset = (uInt32)ptr & 0xFFF;
  baseAddr = (uInt32)ptr & 0xFFFFF000;
  child = getTask(pid);
  //Calculate The Page Table Index And Page Directory Index
  dI = (baseAddr/(1024*4096));
  tI = ((baseAddr-(dI*(1024*4096)))/4096);
  remapPage(child->tss.cr3,0x5A00000);
  for (i=0;i<0x1000;i++) {
    remapPage(childPageDir[i],0x5A01000 + (i * 0x1000));
    }
  for (x=(_current->oInfo.vmStart/(1024*4096));x<1024;x++) {
    pageTableSrc = (uInt32 *)(tablesBaseAddress + (4096*x));
    for (y=0;y<1024;y++) {
      //Loop Through The Page Table Find An UnAllocated Page
      if ((uInt32)pageTableSrc[y] == (uInt32)0x0) {
        if (count > 1) {
          for (c=0;((c<count) && (y+c < 1024));c++) {
            if ((uInt32)pageTableSrc[y+c] != (uInt32)0x0) {
              c = -1;
              break;
              }
            }
          if (c != -1) {
            for (c=0;c<count;c++) {
              if ((tI + c) >= 0x1000) {
                dI++;
                tI = 0-c;
                }
              childPageTable = (uInt32 *)(0x5A01000 + (0x1000 * dI));
              remapPage(childPageTable[tI+c],((x*(1024*4096))+((y+c)*4096)));
              }
            unmapPage(0x5A00000,1);
            for (i=0;i<0x1000;i++) {
              unmapPage((0x5A01000 + (i*0x1000)),1);
              }
            return((void *)((x*(1024*4096))+(y*4096)+offset));
            }
          }
        else {
          //Map A Physical Page To The Virtual Page
          childPageTable = (uInt32 *)(0x5A01000 + (0x1000 * dI));
          remapPage(childPageTable[tI],((x*(1024*4096))+(y*4096)));
          //Return The Address Of The Mapped In Memory
          unmapPage(0x5A00000,1);
          for (i=0;i<0x1000;i++) {
            unmapPage((0x5A01000 + (i*0x1000)),1);
            }
          return((void *)((x*(1024*4096))+(y*4096)+offset));
          }
        }
      }
    }
  return(0x0);
  }

void unmapPages(void *ptr,uInt32 size) {
  uInt32 baseAddr = (uInt32)ptr & 0xFFFFF000;
  uInt32 dI = 0x0,tI = 0x0;
  uInt32 y = 0x0;
  uInt32 *pageTable = 0x0;
  
  dI = (baseAddr/(1024*4096));
  tI = ((baseAddr-(dI*(1024*4096)))/4096);  
  pageTable = (uInt32 *)(tablesBaseAddress + (4096*dI));
  for (y=tI;y<(tI+((size+4095)/4096));y++) {
    pageTable[y] = 0x0;
    }
  return;
  }