/////////////////////////////////////////////////////////////////////////
// $Id: icache.h,v 1.54 2010-05-18 07:28:04 sshwarts Exp $
/////////////////////////////////////////////////////////////////////////
//
//   Copyright (c) 2007-2010 Stanislav Shwartsman
//          Written by Stanislav Shwartsman [sshwarts at sourceforge net]
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2 of the License, or (at your option) any later version.
//
//  This library is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA B 02110-1301 USA
//
/////////////////////////////////////////////////////////////////////////

#ifndef BX_ICACHE_H
#define BX_ICACHE_H

// bit 31 indicates code page
const Bit32u ICacheWriteStampInvalid  = 0xffffffff;
const Bit32u ICacheWriteStampStart    = 0x7fffffff;
const Bit32u ICacheWriteStampFetchModeMask = ~ICacheWriteStampStart;

#if BX_SUPPORT_TRACE_CACHE
extern void handleSMC(bx_phy_address pAddr);
#endif

class bxPageWriteStampTable
{
  // A table (dynamically allocated) to store write-stamp generation IDs.
  // Each time a write occurs to a physical page, a generation ID is
  // decremented. Only iCache entries which have write stamps matching
  // the physical page write stamp are valid.
  Bit32u *pageWriteStampTable;

#define PHY_MEM_PAGES (1024*1024)

public:
  bxPageWriteStampTable() {
    pageWriteStampTable = new Bit32u[PHY_MEM_PAGES];
    resetWriteStamps();
  }
 ~bxPageWriteStampTable() { delete [] pageWriteStampTable; }

  BX_CPP_INLINE Bit32u hash(bx_phy_address pAddr) const {
    // can share writeStamps between multiple pages if >32 bit phy address
    return ((Bit32u) pAddr) >> 12;
  }

  BX_CPP_INLINE Bit32u getPageWriteStamp(bx_phy_address pAddr) const
  {
    return pageWriteStampTable[hash(pAddr)];
  }

  BX_CPP_INLINE const Bit32u *getPageWriteStampPtr(bx_phy_address pAddr) const
  {
    return &pageWriteStampTable[hash(pAddr)];
  }

  BX_CPP_INLINE void setPageWriteStamp(bx_phy_address pAddr, Bit32u pageWriteStamp)
  {
    pageWriteStampTable[hash(pAddr)] = pageWriteStamp;
  }

  BX_CPP_INLINE void markICache(bx_phy_address pAddr)
  {
    pageWriteStampTable[hash(pAddr)] |= ICacheWriteStampFetchModeMask;
  }

  BX_CPP_INLINE void decWriteStamp(bx_phy_address pAddr)
  {
    Bit32u index = hash(pAddr);
    if (pageWriteStampTable[index] & ICacheWriteStampFetchModeMask) {
#if BX_SUPPORT_TRACE_CACHE
      handleSMC(pAddr); // one of the CPUs might be running trace from this page
#endif
      // Decrement page write stamp, so iCache entries with older stamps are
      // effectively invalidated.
      pageWriteStampTable[index] = (pageWriteStampTable[index] - 1) & ~ICacheWriteStampFetchModeMask;
    }
  }

  BX_CPP_INLINE void resetWriteStamps(void);
};

BX_CPP_INLINE void bxPageWriteStampTable::resetWriteStamps(void)
{
  for (Bit32u i=0; i<PHY_MEM_PAGES; i++) {
    pageWriteStampTable[i] = ICacheWriteStampStart - 1;
  }
}

extern bxPageWriteStampTable pageWriteStampTable;

#define BxICacheEntries (64 * 1024)  // Must be a power of 2.
#define BxICacheMemPool (384 * 1024)

#if BX_SUPPORT_TRACE_CACHE
  #define BX_MAX_TRACE_LENGTH 32
#endif

struct bxICacheEntry_c
{
  bx_phy_address pAddr; // Physical address of the instruction
  Bit32u writeStamp;    // Generation ID. Each write to a physical page
                        // decrements this value
#if BX_SUPPORT_TRACE_CACHE
  Bit32u tlen;          // Trace length in instructions
  bxInstruction_c *i;
#else
  // ... define as array of 1 to simplify merge with trace cache code
  bxInstruction_c i[1];
#endif
};

#define BX_ICACHE_INVALID_PHY_ADDRESS (bx_phy_address(-1))

class BOCHSAPI bxICache_c {
public:
  bxICacheEntry_c entry[BxICacheEntries];
#if BX_SUPPORT_TRACE_CACHE
  bxInstruction_c mpool[BxICacheMemPool];
  unsigned mpindex;

#define BX_ICACHE_PAGE_SPLIT_ENTRIES 8 /* must be power of two */
  struct pageSplitEntryIndex {
    bx_phy_address ppf; // Physical address of 2nd page of the trace 
    bxICacheEntry_c *e; // Pointer to icache entry
  } pageSplitIndex[BX_ICACHE_PAGE_SPLIT_ENTRIES];
  int nextPageSplitIndex;
#endif

public:
  bxICache_c() { flushICacheEntries(); }

  BX_CPP_INLINE unsigned hash(bx_phy_address pAddr, unsigned fetchModeMask) const
  {
//  return ((pAddr + (pAddr << 2) + (pAddr>>6)) & (BxICacheEntries-1)) ^ fetchModeMask;
    return ((pAddr) & (BxICacheEntries-1)) ^ fetchModeMask;
  }

#if BX_SUPPORT_TRACE_CACHE
  BX_CPP_INLINE void alloc_trace(bxICacheEntry_c *e)
  {
    if (mpindex + BX_MAX_TRACE_LENGTH > BxICacheMemPool) {
      flushICacheEntries();
    }
    e->i = &mpool[mpindex];
    e->tlen = 0;
  }

  BX_CPP_INLINE void commit_trace(unsigned len) { mpindex += len; }

  BX_CPP_INLINE void commit_page_split_trace(bx_phy_address paddr, bxICacheEntry_c *entry)
  {
    mpindex++;  // commit_trace(1)

    // register page split entry
    if (pageSplitIndex[nextPageSplitIndex].ppf != BX_ICACHE_INVALID_PHY_ADDRESS)
      pageSplitIndex[nextPageSplitIndex].e->writeStamp = ICacheWriteStampInvalid;

    pageSplitIndex[nextPageSplitIndex].ppf = paddr;
    pageSplitIndex[nextPageSplitIndex].e = entry;

    nextPageSplitIndex = (nextPageSplitIndex+1) & (BX_ICACHE_PAGE_SPLIT_ENTRIES-1);
  }

  BX_CPP_INLINE void handleSMC(bx_phy_address pAddr);
#endif

  BX_CPP_INLINE void purgeICacheEntries(void);
  BX_CPP_INLINE void flushICacheEntries(void);

  BX_CPP_INLINE bxICacheEntry_c* get_entry(bx_phy_address pAddr, unsigned fetchModeMask)
  {
    return &(entry[hash(pAddr, fetchModeMask)]);
  }

};

BX_CPP_INLINE void bxICache_c::flushICacheEntries(void)
{
  bxICacheEntry_c* e = entry;
  unsigned i;

  for (i=0; i<BxICacheEntries; i++, e++)
    e->writeStamp = ICacheWriteStampInvalid;

#if BX_SUPPORT_TRACE_CACHE
  for (i=0;i<BX_ICACHE_PAGE_SPLIT_ENTRIES;i++)
    pageSplitIndex[i].ppf = BX_ICACHE_INVALID_PHY_ADDRESS;

  nextPageSplitIndex = 0;
  mpindex = 0;
#endif
}

#if BX_SUPPORT_TRACE_CACHE
BX_CPP_INLINE void bxICache_c::handleSMC(bx_phy_address pAddr)
{
  pAddr = LPFOf(pAddr);

  for (unsigned i=0;i<BX_ICACHE_PAGE_SPLIT_ENTRIES;i++) {
    if (pAddr == pageSplitIndex[i].ppf) {
      pageSplitIndex[i].e->writeStamp = ICacheWriteStampInvalid;
      pageSplitIndex[i].ppf = BX_ICACHE_INVALID_PHY_ADDRESS;
    }
  }
}
#endif

// Since the write stamps may overflow if we always simply decrese them,
// this function has to be called often enough that we can reset them.
BX_CPP_INLINE void bxICache_c::purgeICacheEntries(void)
{
  flushICacheEntries();
}

extern void purgeICaches(void);
extern void flushICaches(void);

#endif