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/*

 * mmu.c -- memory and TLB access

 */

#include "common.h"

#include "stdarg.h"

#include "romlib.h"

#include "mmu.h"

#include "start.h"

static Word tlbIndex;

static Word tlbEntryHi;

static Word tlbEntryLo;

static Word badAddress;

Word mmuReadWord(Word vAddr) {

  return *(Word *)vAddr;

}

Half mmuReadHalf(Word vAddr) {

  return *(Half *)vAddr;

}

Byte mmuReadByte(Word vAddr) {

  return *(Byte *)vAddr;

}

void mmuWriteWord(Word vAddr, Word data) {

  *(Word *)vAddr = data;

}

void mmuWriteHalf(Word vAddr, Half data) {

  *(Half *)vAddr = data;

}

void mmuWriteByte(Word vAddr, Byte data) {

  *(Byte *)vAddr = data;

}

Word mmuGetIndex(void) {

  return tlbIndex;

}

void mmuSetIndex(Word value) {

  tlbIndex = value;

}

Word mmuGetEntryHi(void) {

  return tlbEntryHi;

}

void mmuSetEntryHi(Word value) {

  tlbEntryHi = value;

}

Word mmuGetEntryLo(void) {

  return tlbEntryLo;

}

void mmuSetEntryLo(Word value) {

  tlbEntryLo = value;

}

Word mmuGetBadAddr(void) {

  return badAddress;

}

void mmuSetBadAddr(Word value) {

  badAddress = value;

}

TLB_Entry mmuGetTLB(int index) {

  Word hi;

  Word lo;

  TLB_Entry result;

  hi = getTLB_HI(index);

  lo = getTLB_LO(index);

  result.page = hi & PAGE_MASK;

  result.frame = lo & PAGE_MASK;

  result.write = (lo & TLB_WRITE) ? true : false;

  result.valid = (lo & TLB_VALID) ? true : false;

  return result;

}

void mmuSetTLB(int index, TLB_Entry tlbEntry) {

  Word flags;

  flags = 0;

  if (tlbEntry.write) {

    flags |= TLB_WRITE;

  }

  if (tlbEntry.valid) {

    flags |= TLB_VALID;

  }

  setTLB(index, tlbEntry.page, tlbEntry.frame | flags);

}