/**

 * $Id$

 *

 * SH4 MMU implementation based on address space page maps. This module

 * is responsible for all address decoding functions. 

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 */

#define MODULE sh4_module

#include <stdio.h>

#include <assert.h>

#include "sh4/sh4mmio.h"

#include "sh4/sh4core.h"

#include "sh4/sh4trans.h"

#include "dreamcast.h"

#include "mem.h"

#include "mmu.h"

#define RAISE_TLB_ERROR(code, vpn) \

    MMIO_WRITE(MMU, TEA, vpn); \

    MMIO_WRITE(MMU, PTEH, ((MMIO_READ(MMU, PTEH) & 0x000003FF) | (vpn&0xFFFFFC00))); \

    sh4_raise_tlb_exception(code);

#define RAISE_MEM_ERROR(code, vpn) \

    MMIO_WRITE(MMU, TEA, vpn); \

    MMIO_WRITE(MMU, PTEH, ((MMIO_READ(MMU, PTEH) & 0x000003FF) | (vpn&0xFFFFFC00))); \

    sh4_raise_exception(code);

#define RAISE_TLB_MULTIHIT_ERROR(vpn) \

    sh4_raise_reset(EXC_TLB_MULTI_HIT); \

    MMIO_WRITE(MMU, TEA, vpn); \

    MMIO_WRITE(MMU, PTEH, ((MMIO_READ(MMU, PTEH) & 0x000003FF) | (vpn&0xFFFFFC00)));

/* An entry is a 1K entry if it's one of the mmu_utlb_1k_pages entries */

#define IS_1K_PAGE_ENTRY(ent)  ( ((uintptr_t)(((struct utlb_1k_entry *)ent) - &mmu_utlb_1k_pages[0])) < UTLB_ENTRY_COUNT )

/* Primary address space (used directly by SH4 cores) */

mem_region_fn_t *sh4_address_space;

mem_region_fn_t *sh4_user_address_space;

/* MMU-mapped storequeue targets. Only used with TLB on */

mem_region_fn_t *storequeue_address_space; 

mem_region_fn_t *storequeue_user_address_space; 

/* Accessed from the UTLB accessor methods */

uint32_t mmu_urc;

uint32_t mmu_urb;

/* Module globals */

static struct itlb_entry mmu_itlb[ITLB_ENTRY_COUNT];

static struct utlb_entry mmu_utlb[UTLB_ENTRY_COUNT];

static struct utlb_page_entry mmu_utlb_pages[UTLB_ENTRY_COUNT];

static uint32_t mmu_lrui;

static uint32_t mmu_asid; // current asid

/* Structures for 1K page handling */

static struct utlb_1k_entry mmu_utlb_1k_pages[UTLB_ENTRY_COUNT];

static int mmu_utlb_1k_free_list[UTLB_ENTRY_COUNT];

static int mmu_utlb_1k_free_index;

/* Function prototypes */

static void mmu_invalidate_tlb();

static void mmu_utlb_register_all();

static void mmu_utlb_remove_entry(int);

static void mmu_utlb_insert_entry(int);

static void mmu_register_mem_region( uint32_t start, uint32_t end, mem_region_fn_t fn );

static void mmu_register_user_mem_region( uint32_t start, uint32_t end, mem_region_fn_t fn );

static void mmu_set_tlb_enabled( int tlb_on );

static void mmu_set_tlb_asid( uint32_t asid );

static void mmu_set_storequeue_protected( int protected );

static gboolean mmu_utlb_map_pages( mem_region_fn_t priv_page, mem_region_fn_t user_page, sh4addr_t start_addr, int npages );

static void mmu_utlb_remap_pages( gboolean remap_priv, gboolean remap_user, int entryNo );

static gboolean mmu_utlb_unmap_pages( gboolean unmap_priv, gboolean unmap_user, sh4addr_t start_addr, int npages );

static gboolean mmu_ext_page_remapped( sh4addr_t page, mem_region_fn_t fn, void *user_data );

static void mmu_utlb_1k_init();

static struct utlb_1k_entry *mmu_utlb_1k_alloc();

static void mmu_utlb_1k_free( struct utlb_1k_entry *entry );

static int32_t FASTCALL tlb_protected_read( sh4addr_t addr, void *exc );

static void FASTCALL tlb_protected_write( sh4addr_t addr, uint32_t val, void *exc );

static void FASTCALL tlb_initial_write( sh4addr_t addr, uint32_t val, void *exc );

static uint32_t get_tlb_size_mask( uint32_t flags );

static uint32_t get_tlb_size_pages( uint32_t flags );

/*********************** Module public functions ****************************/

/**

 * Allocate memory for the address space maps, and initialize them according

 * to the default (reset) values. (TLB is disabled by default)

 */

void MMU_init()

{

    sh4_address_space = mem_alloc_pages( sizeof(mem_region_fn_t) * 256 );

    sh4_user_address_space = mem_alloc_pages( sizeof(mem_region_fn_t) * 256 );

    storequeue_address_space = mem_alloc_pages( sizeof(mem_region_fn_t) * 4 );

    storequeue_user_address_space = mem_alloc_pages( sizeof(mem_region_fn_t) * 4 );

    mmu_set_tlb_enabled(0);

    mmu_register_user_mem_region( 0x80000000, 0x00000000, &mem_region_address_error );

    mmu_register_user_mem_region( 0xE0000000, 0xE4000000, &p4_region_storequeue);

    /* Setup P4 tlb/cache access regions */

    mmu_register_mem_region( 0xE0000000, 0xE4000000, &p4_region_storequeue );

    mmu_register_mem_region( 0xE4000000, 0xF0000000, &mem_region_unmapped );

    mmu_register_mem_region( 0xF0000000, 0xF1000000, &p4_region_icache_addr );

    mmu_register_mem_region( 0xF1000000, 0xF2000000, &p4_region_icache_data );

    mmu_register_mem_region( 0xF2000000, 0xF3000000, &p4_region_itlb_addr );

    mmu_register_mem_region( 0xF3000000, 0xF4000000, &p4_region_itlb_data );

    mmu_register_mem_region( 0xF4000000, 0xF5000000, &p4_region_ocache_addr );

    mmu_register_mem_region( 0xF5000000, 0xF6000000, &p4_region_ocache_data );

    mmu_register_mem_region( 0xF6000000, 0xF7000000, &p4_region_utlb_addr );

    mmu_register_mem_region( 0xF7000000, 0xF8000000, &p4_region_utlb_data );

    mmu_register_mem_region( 0xF8000000, 0x00000000, &mem_region_unmapped );

    /* Setup P4 control region */

    mmu_register_mem_region( 0xFF000000, 0xFF001000, &mmio_region_MMU.fn );

    mmu_register_mem_region( 0xFF100000, 0xFF101000, &mmio_region_PMM.fn );

    mmu_register_mem_region( 0xFF200000, 0xFF201000, &mmio_region_UBC.fn );

    mmu_register_mem_region( 0xFF800000, 0xFF801000, &mmio_region_BSC.fn );

    mmu_register_mem_region( 0xFF900000, 0xFFA00000, &mem_region_unmapped ); // SDMR2 + SDMR3

    mmu_register_mem_region( 0xFFA00000, 0xFFA01000, &mmio_region_DMAC.fn );

    mmu_register_mem_region( 0xFFC00000, 0xFFC01000, &mmio_region_CPG.fn );

    mmu_register_mem_region( 0xFFC80000, 0xFFC81000, &mmio_region_RTC.fn );

    mmu_register_mem_region( 0xFFD00000, 0xFFD01000, &mmio_region_INTC.fn );

    mmu_register_mem_region( 0xFFD80000, 0xFFD81000, &mmio_region_TMU.fn );

    mmu_register_mem_region( 0xFFE00000, 0xFFE01000, &mmio_region_SCI.fn );

    mmu_register_mem_region( 0xFFE80000, 0xFFE81000, &mmio_region_SCIF.fn );

    mmu_register_mem_region( 0xFFF00000, 0xFFF01000, &mem_region_unmapped ); // H-UDI

    register_mem_page_remapped_hook( mmu_ext_page_remapped, NULL );

    mmu_utlb_1k_init();

    /* Ensure the code regions are executable */

    mem_unprotect( mmu_utlb_pages, sizeof(mmu_utlb_pages) );

    mem_unprotect( mmu_utlb_1k_pages, sizeof(mmu_utlb_1k_pages) );

}

void MMU_reset()

{

    mmio_region_MMU_write( CCR, 0 );

    mmio_region_MMU_write( MMUCR, 0 );

}

void MMU_save_state( FILE *f )

{

    fwrite( &mmu_itlb, sizeof(mmu_itlb), 1, f );

    fwrite( &mmu_utlb, sizeof(mmu_utlb), 1, f );

    fwrite( &mmu_urc, sizeof(mmu_urc), 1, f );

    fwrite( &mmu_urb, sizeof(mmu_urb), 1, f );

    fwrite( &mmu_lrui, sizeof(mmu_lrui), 1, f );

    fwrite( &mmu_asid, sizeof(mmu_asid), 1, f );

}

int MMU_load_state( FILE *f )

{

    if( fread( &mmu_itlb, sizeof(mmu_itlb), 1, f ) != 1 ) {

        return 1;

    }

    if( fread( &mmu_utlb, sizeof(mmu_utlb), 1, f ) != 1 ) {

        return 1;

    }

    if( fread( &mmu_urc, sizeof(mmu_urc), 1, f ) != 1 ) {

        return 1;

    }

    if( fread( &mmu_urc, sizeof(mmu_urb), 1, f ) != 1 ) {

        return 1;

    }

    if( fread( &mmu_lrui, sizeof(mmu_lrui), 1, f ) != 1 ) {

        return 1;

    }

    if( fread( &mmu_asid, sizeof(mmu_asid), 1, f ) != 1 ) {

        return 1;

    }

    uint32_t mmucr = MMIO_READ(MMU,MMUCR);

    mmu_set_tlb_enabled(mmucr&MMUCR_AT);

    mmu_set_storequeue_protected(mmucr&MMUCR_SQMD);

    return 0;

}

/**

 * LDTLB instruction implementation. Copies PTEH, PTEL and PTEA into the UTLB

 * entry identified by MMUCR.URC. Does not modify MMUCR or the ITLB.

 */

void MMU_ldtlb()

{

    mmu_urc %= mmu_urb;

    if( mmu_utlb[mmu_urc].flags & TLB_VALID )

        mmu_utlb_remove_entry( mmu_urc );

    mmu_utlb[mmu_urc].vpn = MMIO_READ(MMU, PTEH) & 0xFFFFFC00;

    mmu_utlb[mmu_urc].asid = MMIO_READ(MMU, PTEH) & 0x000000FF;

    mmu_utlb[mmu_urc].ppn = MMIO_READ(MMU, PTEL) & 0x1FFFFC00;

    mmu_utlb[mmu_urc].flags = MMIO_READ(MMU, PTEL) & 0x00001FF;

    mmu_utlb[mmu_urc].pcmcia = MMIO_READ(MMU, PTEA);

    mmu_utlb[mmu_urc].mask = get_tlb_size_mask(mmu_utlb[mmu_urc].flags);

    if( mmu_utlb[mmu_urc].flags & TLB_VALID )

        mmu_utlb_insert_entry( mmu_urc );

}

MMIO_REGION_READ_FN( MMU, reg )

{

    reg &= 0xFFF;

    switch( reg ) {

    case MMUCR:

        mmu_urc %= mmu_urb;

        return MMIO_READ( MMU, MMUCR) | (mmu_urc<<10) | ((mmu_urb&0x3F)<<18) | (mmu_lrui<<26);

    default:

        return MMIO_READ( MMU, reg );

    }

}

MMIO_REGION_WRITE_FN( MMU, reg, val )

{

    uint32_t tmp;

    reg &= 0xFFF;

    switch(reg) {

    case SH4VER:

        return;

    case PTEH:

        val &= 0xFFFFFCFF;

        if( (val & 0xFF) != mmu_asid ) {

            mmu_set_tlb_asid( val&0xFF );

            sh4_icache.page_vma = -1; // invalidate icache as asid has changed

        }

        break;

    case PTEL:

        val &= 0x1FFFFDFF;

        break;

    case PTEA:

        val &= 0x0000000F;

        break;

    case TRA:

        val &= 0x000003FC;

        break;

    case EXPEVT:

    case INTEVT:

        val &= 0x00000FFF;

        break;

    case MMUCR:

        if( val & MMUCR_TI ) {

            mmu_invalidate_tlb();

        }

        mmu_urc = (val >> 10) & 0x3F;

        mmu_urb = (val >> 18) & 0x3F;

        if( mmu_urb == 0 ) {

            mmu_urb = 0x40;

        }

        mmu_lrui = (val >> 26) & 0x3F;

        val &= 0x00000301;

        tmp = MMIO_READ( MMU, MMUCR );

        if( (val ^ tmp) & (MMUCR_SQMD) ) {

            mmu_set_storequeue_protected( val & MMUCR_SQMD );

        }

        if( (val ^ tmp) & (MMUCR_AT) ) {

            // AT flag has changed state - flush the xlt cache as all bets

            // are off now. We also need to force an immediate exit from the

            // current block

            mmu_set_tlb_enabled( val & MMUCR_AT );

            MMIO_WRITE( MMU, MMUCR, val );

            sh4_flush_icache();

        }

        break;

    case CCR:

        CCN_set_cache_control( val );

        val &= 0x81A7;

        break;

    case MMUUNK1:

        /* Note that if the high bit is set, this appears to reset the machine.

         * Not emulating this behaviour yet until we know why...

         */

        val &= 0x00010007;

        break;

    case QACR0:

    case QACR1:

        val &= 0x0000001C;

        break;

    case PMCR1:

        PMM_write_control(0, val);

        val &= 0x0000C13F;

        break;

    case PMCR2:

        PMM_write_control(1, val);

        val &= 0x0000C13F;

        break;

    default:

        break;

    }

    MMIO_WRITE( MMU, reg, val );

}

/********************** 1K Page handling ***********************/

/* Since we use 4K pages as our native page size, 1K pages need a bit of extra

 * effort to manage - we justify this on the basis that most programs won't

 * actually use 1K pages, so we may as well optimize for the common case.

 * 

 * Implementation uses an intermediate page entry (the utlb_1k_entry) that

 * redirects requests to the 'real' page entry. These are allocated on an

 * as-needed basis, and returned to the pool when all subpages are empty.

 */ 

static void mmu_utlb_1k_init()

{

    int i;

    for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

        mmu_utlb_1k_free_list[i] = i;

        mmu_utlb_1k_init_vtable( &mmu_utlb_1k_pages[i] );

    }

    mmu_utlb_1k_free_index = 0;

}

static struct utlb_1k_entry *mmu_utlb_1k_alloc()

{

    assert( mmu_utlb_1k_free_index < UTLB_ENTRY_COUNT );

    struct utlb_1k_entry *entry = &mmu_utlb_1k_pages[mmu_utlb_1k_free_index++];

    return entry;

}    

static void mmu_utlb_1k_free( struct utlb_1k_entry *ent )

{

    unsigned int entryNo = ent - &mmu_utlb_1k_pages[0];

    assert( entryNo < UTLB_ENTRY_COUNT );

    assert( mmu_utlb_1k_free_index > 0 );

    mmu_utlb_1k_free_list[--mmu_utlb_1k_free_index] = entryNo;

}

/********************** Address space maintenance *************************/

/**

 * MMU accessor functions just increment URC - fixup here if necessary

 */

static inline void mmu_urc_fixup()

{

   mmu_urc %= mmu_urb; 

}

static void mmu_register_mem_region( uint32_t start, uint32_t end, mem_region_fn_t fn )

{

    int count = (end - start) >> 12;

    mem_region_fn_t *ptr = &sh4_address_space[start>>12];

    while( count-- > 0 ) {

        *ptr++ = fn;

    }

}

static void mmu_register_user_mem_region( uint32_t start, uint32_t end, mem_region_fn_t fn )

{

    int count = (end - start) >> 12;

    mem_region_fn_t *ptr = &sh4_user_address_space[start>>12];

    while( count-- > 0 ) {

        *ptr++ = fn;

    }

}

static gboolean mmu_ext_page_remapped( sh4addr_t page, mem_region_fn_t fn, void *user_data )

{

    int i;

    if( (MMIO_READ(MMU,MMUCR)) & MMUCR_AT ) {

        /* TLB on */

        sh4_address_space[(page|0x80000000)>>12] = fn; /* Direct map to P1 and P2 */

        sh4_address_space[(page|0xA0000000)>>12] = fn;

        /* Scan UTLB and update any direct-referencing entries */

    } else {

        /* Direct map to U0, P0, P1, P2, P3 */

        for( i=0; i<= 0xC0000000; i+= 0x20000000 ) {

            sh4_address_space[(page|i)>>12] = fn;

        }

        for( i=0; i < 0x80000000; i+= 0x20000000 ) {

            sh4_user_address_space[(page|i)>>12] = fn;

        }

    }

}

static void mmu_set_tlb_enabled( int tlb_on )

{

    mem_region_fn_t *ptr, *uptr;

    int i;

    if( tlb_on ) {

        mmu_register_mem_region(0x00000000, 0x80000000, &mem_region_tlb_miss );

        mmu_register_mem_region(0xC0000000, 0xE0000000, &mem_region_tlb_miss );

        mmu_register_user_mem_region(0x00000000, 0x80000000, &mem_region_tlb_miss );

        for( i=0, ptr = storequeue_address_space, uptr = storequeue_user_address_space; 

             i<0x04000000; i+= LXDREAM_PAGE_SIZE ) {

            *ptr++ = &mem_region_tlb_miss;

            *uptr++ = &mem_region_tlb_miss;

        }

        mmu_utlb_register_all();

    } else {

        for( i=0, ptr = sh4_address_space; i<7; i++, ptr += LXDREAM_PAGE_TABLE_ENTRIES ) {

            memcpy( ptr, ext_address_space, sizeof(mem_region_fn_t) * LXDREAM_PAGE_TABLE_ENTRIES );

        }

        for( i=0, ptr = sh4_user_address_space; i<4; i++, ptr += LXDREAM_PAGE_TABLE_ENTRIES ) {

            memcpy( ptr, ext_address_space, sizeof(mem_region_fn_t) * LXDREAM_PAGE_TABLE_ENTRIES );

        }

    }

}

static void mmu_set_storequeue_protected( int protected ) 

{

    if( protected ) {

        mmu_register_user_mem_region( 0xE0000000, 0xE4000000, &mem_region_address_error );

    } else {

        mmu_register_user_mem_region( 0xE0000000, 0xE4000000, &p4_region_storequeue );

    }

}

static void mmu_set_tlb_asid( uint32_t asid )

{

    /* Scan for pages that need to be remapped */

    int i;

    if( IS_SV_ENABLED() ) {

        for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

            if( mmu_utlb[i].flags & TLB_VALID ) {

                if( (mmu_utlb[i].flags & TLB_SHARE) == 0 ) {

                    if( mmu_utlb[i].asid == mmu_asid ) { // Matches old ASID - unmap out

                        if( !mmu_utlb_unmap_pages( FALSE, TRUE, mmu_utlb[i].vpn&mmu_utlb[i].mask,

                                get_tlb_size_pages(mmu_utlb[i].flags) ) )

                            mmu_utlb_remap_pages( FALSE, TRUE, i );

                    } else if( mmu_utlb[i].asid == asid ) { // Matches new ASID - map in

                        mmu_utlb_map_pages( NULL, mmu_utlb_pages[i].user_fn, 

                                mmu_utlb[i].vpn&mmu_utlb[i].mask, 

                                get_tlb_size_pages(mmu_utlb[i].flags) );  

                    }

                }

            }

        }

    } else {

        // Remap both Priv+user pages

        for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

            if( mmu_utlb[i].flags & TLB_VALID ) {

                if( (mmu_utlb[i].flags & TLB_SHARE) == 0 ) {

                    if( mmu_utlb[i].asid == mmu_asid ) { // Matches old ASID - unmap out

                        if( !mmu_utlb_unmap_pages( TRUE, TRUE, mmu_utlb[i].vpn&mmu_utlb[i].mask,

                                get_tlb_size_pages(mmu_utlb[i].flags) ) )

                            mmu_utlb_remap_pages( TRUE, TRUE, i );

                    } else if( mmu_utlb[i].asid == asid ) { // Matches new ASID - map in

                        mmu_utlb_map_pages( &mmu_utlb_pages[i].fn, mmu_utlb_pages[i].user_fn, 

                                mmu_utlb[i].vpn&mmu_utlb[i].mask, 

                                get_tlb_size_pages(mmu_utlb[i].flags) );  

                    }

                }

            }

        }

    }

    mmu_asid = asid;

}

static uint32_t get_tlb_size_mask( uint32_t flags )

{

    switch( flags & TLB_SIZE_MASK ) {

    case TLB_SIZE_1K: return MASK_1K;

    case TLB_SIZE_4K: return MASK_4K;

    case TLB_SIZE_64K: return MASK_64K;

    case TLB_SIZE_1M: return MASK_1M;

    default: return 0; /* Unreachable */

    }

}

static uint32_t get_tlb_size_pages( uint32_t flags )

{

    switch( flags & TLB_SIZE_MASK ) {

    case TLB_SIZE_1K: return 0;

    case TLB_SIZE_4K: return 1;

    case TLB_SIZE_64K: return 16;

    case TLB_SIZE_1M: return 256;

    default: return 0; /* Unreachable */

    }

}

/**

 * Add a new TLB entry mapping to the address space table. If any of the pages

 * are already mapped, they are mapped to the TLB multi-hit page instead.

 * @return FALSE if a TLB multihit situation was detected, otherwise TRUE.

 */ 

static gboolean mmu_utlb_map_pages( mem_region_fn_t priv_page, mem_region_fn_t user_page, sh4addr_t start_addr, int npages )

{

    mem_region_fn_t *ptr = &sh4_address_space[start_addr >> 12];

    mem_region_fn_t *uptr = &sh4_user_address_space[start_addr >> 12];

    gboolean mapping_ok = TRUE;

    int i;

    if( (start_addr & 0xFC000000) == 0xE0000000 ) {

        /* Storequeue mapping */

        ptr = &storequeue_address_space[(start_addr-0xE0000000) >> 12];

        uptr = &storequeue_user_address_space[(start_addr-0xE0000000) >> 12];

    } else if( (start_addr & 0xE0000000) == 0xC0000000 ) {

        user_page = NULL; /* No user access to P3 region */

    } else if( start_addr >= 0x80000000 ) {

        return TRUE; // No mapping - legal but meaningless

    }

    if( npages == 0 ) {

        struct utlb_1k_entry *ent;

        int i, idx = (start_addr >> 10) & 0x03;

        if( IS_1K_PAGE_ENTRY(*ptr) ) {

            ent = (struct utlb_1k_entry *)*ptr;

        } else {

            ent = mmu_utlb_1k_alloc();

            /* New 1K struct - init to previous contents of region */

            for( i=0; i<4; i++ ) {

                ent->subpages[i] = *ptr;

                ent->user_subpages[i] = *uptr;

            }

            *ptr = &ent->fn;

            *uptr = &ent->user_fn;

        }

        if( priv_page != NULL ) {

            if( ent->subpages[idx] == &mem_region_tlb_miss ) {

                ent->subpages[idx] = priv_page;

            } else {

                mapping_ok = FALSE;

                ent->subpages[idx] = &mem_region_tlb_multihit;

            }

        }

        if( user_page != NULL ) {

            if( ent->user_subpages[idx] == &mem_region_tlb_miss ) {

                ent->user_subpages[idx] = user_page;

            } else {

                mapping_ok = FALSE;

                ent->user_subpages[idx] = &mem_region_tlb_multihit;

            }

        }

    } else {

        if( priv_page != NULL ) {

            if( user_page != NULL ) {

                for( i=0; i<npages; i++ ) {

                    if( *ptr == &mem_region_tlb_miss ) {

                        *ptr++ = priv_page;

                        *uptr++ = user_page;

                    } else {

                        mapping_ok = FALSE;

                        *ptr++ = &mem_region_tlb_multihit;

                        *uptr++ = &mem_region_tlb_multihit;

                    }

                }

            } else {

                /* Privileged mapping only */

                for( i=0; i<npages; i++ ) {

                    if( *ptr == &mem_region_tlb_miss ) {

                        *ptr++ = priv_page;

                    } else {

                        mapping_ok = FALSE;

                        *ptr++ = &mem_region_tlb_multihit;

                    }

                }

            }

        } else if( user_page != NULL ) {

            /* User mapping only (eg ASID change remap w/ SV=1) */

            for( i=0; i<npages; i++ ) {

                if( *uptr == &mem_region_tlb_miss ) {

                    *uptr++ = user_page;

                } else {

                    mapping_ok = FALSE;

                    *uptr++ = &mem_region_tlb_multihit;

                }

            }        

        }

    }

    return mapping_ok;

}

/**

 * Remap any pages within the region covered by entryNo, but not including 

 * entryNo itself. This is used to reestablish pages that were previously

 * covered by a multi-hit exception region when one of the pages is removed.

 */

static void mmu_utlb_remap_pages( gboolean remap_priv, gboolean remap_user, int entryNo )

{

    int mask = mmu_utlb[entryNo].mask;

    uint32_t remap_addr = mmu_utlb[entryNo].vpn & mask;

    int i;

    for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

        if( i != entryNo && (mmu_utlb[i].vpn & mask) == remap_addr && (mmu_utlb[i].flags & TLB_VALID) ) {

            /* Overlapping region */

            mem_region_fn_t priv_page = (remap_priv ? &mmu_utlb_pages[i].fn : NULL);

            mem_region_fn_t user_page = (remap_priv ? mmu_utlb_pages[i].user_fn : NULL);

            uint32_t start_addr;

            int npages;

            if( mmu_utlb[i].mask >= mask ) {

                /* entry is no larger than the area we're replacing - map completely */

                start_addr = mmu_utlb[i].vpn & mmu_utlb[i].mask;

                npages = get_tlb_size_pages( mmu_utlb[i].flags );

            } else {

                /* Otherwise map subset - region covered by removed page */

                start_addr = remap_addr;

                npages = get_tlb_size_pages( mmu_utlb[entryNo].flags );

            }

            if( (mmu_utlb[i].flags & TLB_SHARE) || mmu_utlb[i].asid == mmu_asid ) { 

                mmu_utlb_map_pages( priv_page, user_page, start_addr, npages );

            } else if( IS_SV_ENABLED() ) {

                mmu_utlb_map_pages( priv_page, NULL, start_addr, npages );

            }

        }

    }

}

/**

 * Remove a previous TLB mapping (replacing them with the TLB miss region).

 * @return FALSE if any pages were previously mapped to the TLB multihit page, 

 * otherwise TRUE. In either case, all pages in the region are cleared to TLB miss.

 */

static gboolean mmu_utlb_unmap_pages( gboolean unmap_priv, gboolean unmap_user, sh4addr_t start_addr, int npages )

{

    mem_region_fn_t *ptr = &sh4_address_space[start_addr >> 12];

    mem_region_fn_t *uptr = &sh4_user_address_space[start_addr >> 12];

    gboolean unmapping_ok = TRUE;

    int i;

    if( (start_addr & 0xFC000000) == 0xE0000000 ) {

        /* Storequeue mapping */

        ptr = &storequeue_address_space[(start_addr-0xE0000000) >> 12];

        uptr = &storequeue_user_address_space[(start_addr-0xE0000000) >> 12];

    } else if( (start_addr & 0xE0000000) == 0xC0000000 ) {

        unmap_user = FALSE;

    } else if( start_addr >= 0x80000000 ) {

        return TRUE; // No mapping - legal but meaningless

    }

    if( npages == 0 ) { // 1K page

        assert( IS_1K_PAGE_ENTRY( *ptr ) );

        struct utlb_1k_entry *ent = (struct utlb_1k_entry *)*ptr;

        int i, idx = (start_addr >> 10) & 0x03, mergeable=1;

        if( ent->subpages[idx] == &mem_region_tlb_multihit ) {

            unmapping_ok = FALSE;

        }

        if( unmap_priv )

            ent->subpages[idx] = &mem_region_tlb_miss;

        if( unmap_user )

            ent->user_subpages[idx] = &mem_region_tlb_miss;

        /* If all 4 subpages have the same content, merge them together and

         * release the 1K entry

         */

        mem_region_fn_t priv_page = ent->subpages[0];

        mem_region_fn_t user_page = ent->user_subpages[0];

        for( i=1; i<4; i++ ) {

            if( priv_page != ent->subpages[i] || user_page != ent->user_subpages[i] ) {

                mergeable = 0;

                break;

            }

        }

        if( mergeable ) {

            mmu_utlb_1k_free(ent);

            *ptr = priv_page;

            *uptr = user_page;

        }

    } else {

        if( unmap_priv ) {

            if( unmap_user ) {

                for( i=0; i<npages; i++ ) {

                    if( *ptr == &mem_region_tlb_multihit ) {

                        unmapping_ok = FALSE;

                    }

                    *ptr++ = &mem_region_tlb_miss;

                    *uptr++ = &mem_region_tlb_miss;

                }

            } else {

                /* Privileged (un)mapping only */

                for( i=0; i<npages; i++ ) {

                    if( *ptr == &mem_region_tlb_multihit ) {

                        unmapping_ok = FALSE;

                    }

                    *ptr++ = &mem_region_tlb_miss;

                }

            }

        } else if( unmap_user ) {

            /* User (un)mapping only */

            for( i=0; i<npages; i++ ) {

                if( *uptr == &mem_region_tlb_multihit ) {

                    unmapping_ok = FALSE;

                }

                *uptr++ = &mem_region_tlb_miss;

            }            

        }

    }

    return unmapping_ok;

}

static void mmu_utlb_insert_entry( int entry )

{

    struct utlb_entry *ent = &mmu_utlb[entry];

    mem_region_fn_t page = &mmu_utlb_pages[entry].fn;

    mem_region_fn_t upage;

    sh4addr_t start_addr = ent->vpn & ent->mask;

    int npages = get_tlb_size_pages(ent->flags);

    if( (ent->flags & TLB_USERMODE) == 0 ) {

        upage = &mem_region_user_protected;

    } else {        

        upage = page;

    }

    mmu_utlb_pages[entry].user_fn = upage;

    if( (ent->flags & TLB_WRITABLE) == 0 ) {

        page->write_long = (mem_write_fn_t)tlb_protected_write;

        page->write_word = (mem_write_fn_t)tlb_protected_write;

        page->write_byte = (mem_write_fn_t)tlb_protected_write;

        page->write_burst = (mem_write_burst_fn_t)tlb_protected_write;

        mmu_utlb_init_vtable( ent, &mmu_utlb_pages[entry], FALSE );

    } else if( (ent->flags & TLB_DIRTY) == 0 ) {

        page->write_long = (mem_write_fn_t)tlb_initial_write;

        page->write_word = (mem_write_fn_t)tlb_initial_write;

        page->write_byte = (mem_write_fn_t)tlb_initial_write;

        page->write_burst = (mem_write_burst_fn_t)tlb_initial_write;

        mmu_utlb_init_vtable( ent, &mmu_utlb_pages[entry], FALSE );

    } else {

        mmu_utlb_init_vtable( ent, &mmu_utlb_pages[entry], TRUE );

    }

    /* Is page visible? */

    if( (ent->flags & TLB_SHARE) || ent->asid == mmu_asid ) { 

        mmu_utlb_map_pages( page, upage, start_addr, npages );

    } else if( IS_SV_ENABLED() ) {

        mmu_utlb_map_pages( page, NULL, start_addr, npages );

    }

}

static void mmu_utlb_remove_entry( int entry )

{

    int i, j;

    struct utlb_entry *ent = &mmu_utlb[entry];

    sh4addr_t start_addr = ent->vpn&ent->mask;

    mem_region_fn_t *ptr = &sh4_address_space[start_addr >> 12];

    mem_region_fn_t *uptr = &sh4_user_address_space[start_addr >> 12];

    gboolean unmap_user;

    int npages = get_tlb_size_pages(ent->flags);

    if( (ent->flags & TLB_SHARE) || ent->asid == mmu_asid ) {

        unmap_user = TRUE;

    } else if( IS_SV_ENABLED() ) {

        unmap_user = FALSE;

    } else {

        return; // Not mapped

    }

    gboolean clean_unmap = mmu_utlb_unmap_pages( TRUE, unmap_user, start_addr, npages );

    if( !clean_unmap ) {

        mmu_utlb_remap_pages( TRUE, unmap_user, entry );

    }

}

static void mmu_utlb_register_all()

{

    int i;

    for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

        if( mmu_utlb[i].flags & TLB_VALID ) 

            mmu_utlb_insert_entry( i );

    }

}

static void mmu_invalidate_tlb()

{

    int i;

    for( i=0; i<ITLB_ENTRY_COUNT; i++ ) {

        mmu_itlb[i].flags &= (~TLB_VALID);

    }

    if( IS_TLB_ENABLED() ) {

        for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

            if( mmu_utlb[i].flags & TLB_VALID ) {

                mmu_utlb_remove_entry( i );

            }

        }

    }

    for( i=0; i<UTLB_ENTRY_COUNT; i++ ) {

        mmu_utlb[i].flags &= (~TLB_VALID);

    }

}

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

/*                        MMU TLB address translation                         */

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

/**

 * Translate a 32-bit address into a UTLB entry number. Does not check for

 * page protection etc.

 * @return the entryNo if found, -1 if not found, and -2 for a multi-hit.

 */

int mmu_utlb_entry_for_vpn( uint32_t vpn )

{

    mem_region_fn_t fn = sh4_address_space[vpn>>12];

    if( fn >= &mmu_utlb_pages[0].fn && fn < &mmu_utlb_pages[UTLB_ENTRY_COUNT].fn ) {

        return ((struct utlb_page_entry *)fn) - &mmu_utlb_pages[0];

    } else if( fn == &mem_region_tlb_multihit ) {

        return -2;

    } else {

        return -1;

    }

}

/**

 * Perform the actual utlb lookup w/ asid matching.

 * Possible utcomes are:

 *   0..63 Single match - good, return entry found

 *   -1 No match - raise a tlb data miss exception

 *   -2 Multiple matches - raise a multi-hit exception (reset)

 * @param vpn virtual address to resolve

 * @return the resultant UTLB entry, or an error.

 */

static inline int mmu_utlb_lookup_vpn_asid( uint32_t vpn )

{

    int result = -1;

    unsigned int i;

    mmu_urc++;

    if( mmu_urc == mmu_urb || mmu_urc == 0x40 ) {

        mmu_urc = 0;

    }

    for( i = 0; i < UTLB_ENTRY_COUNT; i++ ) {

        if( (mmu_utlb[i].flags & TLB_VALID) &&

                ((mmu_utlb[i].flags & TLB_SHARE) || mmu_asid == mmu_utlb[i].asid) &&

                ((mmu_utlb[i].vpn ^ vpn) & mmu_utlb[i].mask) == 0 ) {

            if( result != -1 ) {

                return -2;

            }

            result = i;

        }

    }

    return result;

}

/**

 * Perform the actual utlb lookup matching on vpn only

 * Possible utcomes are:

 *   0..63 Single match - good, return entry found

 *   -1 No match - raise a tlb data miss exception

 *   -2 Multiple matches - raise a multi-hit exception (reset)

 * @param vpn virtual address to resolve

 * @return the resultant UTLB entry, or an error.

 */

static inline int mmu_utlb_lookup_vpn( uint32_t vpn )

{

    int result = -1;

    unsigned int i;

    mmu_urc++;

    if( mmu_urc == mmu_urb || mmu_urc == 0x40 ) {

        mmu_urc = 0;

    }

    for( i = 0; i < UTLB_ENTRY_COUNT; i++ ) {

        if( (mmu_utlb[i].flags & TLB_VALID) &&

                ((mmu_utlb[i].vpn ^ vpn) & mmu_utlb[i].mask) == 0 ) {

            if( result != -1 ) {

                return -2;

            }

            result = i;

        }

    }

    return result;

}

/**

 * Update the ITLB by replacing the LRU entry with the specified UTLB entry.

 * @return the number (0-3) of the replaced entry.

 */

static int inline mmu_itlb_update_from_utlb( int entryNo )

{

    int replace;

    /* Determine entry to replace based on lrui */

    if( (mmu_lrui & 0x38) == 0x38 ) {

        replace = 0;

        mmu_lrui = mmu_lrui & 0x07;

    } else if( (mmu_lrui & 0x26) == 0x06 ) {

        replace = 1;

        mmu_lrui = (mmu_lrui & 0x19) | 0x20;

    } else if( (mmu_lrui & 0x15) == 0x01 ) {

        replace = 2;

        mmu_lrui = (mmu_lrui & 0x3E) | 0x14;

    } else { // Note - gets invalid entries too

        replace = 3;

        mmu_lrui = (mmu_lrui | 0x0B);

    }

    mmu_itlb[replace].vpn = mmu_utlb[entryNo].vpn;

    mmu_itlb[replace].mask = mmu_utlb[entryNo].mask;

    mmu_itlb[replace].ppn = mmu_utlb[entryNo].ppn;

    mmu_itlb[replace].asid = mmu_utlb[entryNo].asid;

    mmu_itlb[replace].flags = mmu_utlb[entryNo].flags & 0x01DA;

    return replace;

}

/**

 * Perform the actual itlb lookup w/ asid protection

 * Possible utcomes are:

 *   0..63 Single match - good, return entry found

 *   -1 No match - raise a tlb data miss exception

 *   -2 Multiple matches - raise a multi-hit exception (reset)

 * @param vpn virtual address to resolve

 * @return the resultant ITLB entry, or an error.

 */

static inline int mmu_itlb_lookup_vpn_asid( uint32_t vpn )

{

    int result = -1;

    unsigned int i;

    for( i = 0; i < ITLB_ENTRY_COUNT; i++ ) {

        if( (mmu_itlb[i].flags & TLB_VALID) &&

                ((mmu_itlb[i].flags & TLB_SHARE) || mmu_asid == mmu_itlb[i].asid) &&

                ((mmu_itlb[i].vpn ^ vpn) & mmu_itlb[i].mask) == 0 ) {

            if( result != -1 ) {

                return -2;

            }

            result = i;

        }

    }

    if( result == -1 ) {

        int utlbEntry = mmu_utlb_entry_for_vpn( vpn );

        if( utlbEntry < 0 ) {

            return utlbEntry;

        } else {

            return mmu_itlb_update_from_utlb( utlbEntry );

        }

    }

    switch( result ) {

    case 0: mmu_lrui = (mmu_lrui & 0x07); break;

    case 1: mmu_lrui = (mmu_lrui & 0x19) | 0x20; break;

    case 2: mmu_lrui = (mmu_lrui & 0x3E) | 0x14; break;

    case 3: mmu_lrui = (mmu_lrui | 0x0B); break;

    }

    return result;

}

/**

 * Perform the actual itlb lookup on vpn only

 * Possible utcomes are:

 *   0..63 Single match - good, return entry found

 *   -1 No match - raise a tlb data miss exception

 *   -2 Multiple matches - raise a multi-hit exception (reset)

 * @param vpn virtual address to resolve

 * @return the resultant ITLB entry, or an error.

 */

static inline int mmu_itlb_lookup_vpn( uint32_t vpn )

{

    int result = -1;

    unsigned int i;

    for( i = 0; i < ITLB_ENTRY_COUNT; i++ ) {

        if( (mmu_itlb[i].flags & TLB_VALID) &&

                ((mmu_itlb[i].vpn ^ vpn) & mmu_itlb[i].mask) == 0 ) {

            if( result != -1 ) {

                return -2;

            }

            result = i;

        }

    }

    if( result == -1 ) {

        int utlbEntry = mmu_utlb_lookup_vpn( vpn );

        if( utlbEntry < 0 ) {

            return utlbEntry;

        } else {

            return mmu_itlb_update_from_utlb( utlbEntry );

        }

    }

    switch( result ) {

    case 0: mmu_lrui = (mmu_lrui & 0x07); break;

    case 1: mmu_lrui = (mmu_lrui & 0x19) | 0x20; break;

    case 2: mmu_lrui = (mmu_lrui & 0x3E) | 0x14; break;

    case 3: mmu_lrui = (mmu_lrui | 0x0B); break;