/**

 * $Id: xltcache.c,v 1.1 2007-08-23 12:33:27 nkeynes Exp $

 * 

 * Translation cache management. This part is architecture independent.

 *

 * 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.

 */

#include "sh4/xltcache.h"

#include "dreamcast.h"

#include <sys/mman.h>

#include <assert.h>

#define XLAT_LUT_PAGE_BITS 12

#define XLAT_LUT_TOTAL_BITS 28

#define XLAT_LUT_PAGE(addr) (((addr)>>13) & 0xFFFF)

#define XLAT_LUT_ENTRY(addr) (((addr)&0x1FFE) >> 1)

#define XLAT_LUT_PAGES (1<<(XLAT_LUT_TOTAL_BITS-XLAT_LUT_PAGE_BITS))

#define XLAT_LUT_PAGE_ENTRIES (1<<XLAT_LUT_PAGE_BITS)

#define XLAT_LUT_PAGE_SIZE (XLAT_LUT_PAGE_ENTRIES * sizeof(void *))

#define XLAT_LUT_ENTRY_EMPTY (void *)0

#define XLAT_LUT_ENTRY_USED  (void *)1

#define NEXT(block) ( (xlat_cache_block_t)&((block)->code[(block)->size]))

#define BLOCK_FOR_CODE(code) (((xlat_cache_block_t)code)-1)

#define IS_ENTRY_POINT(ent) (ent > XLAT_LUT_ENTRY_USED)

#define IS_ENTRY_USED(ent) (ent != XLAT_LUT_ENTRY_EMPTY)

#define MIN_BLOCK_SIZE 32

#define MIN_TOTAL_SIZE (sizeof(struct xlat_cache_block)+MIN_BLOCK_SIZE)

#define BLOCK_INACTIVE 0

#define BLOCK_ACTIVE 1

#define BLOCK_USED 2

xlat_cache_block_t xlat_new_cache;

xlat_cache_block_t xlat_new_cache_ptr;

xlat_cache_block_t xlat_new_create_ptr;

xlat_cache_block_t xlat_temp_cache;

xlat_cache_block_t xlat_temp_cache_ptr;

xlat_cache_block_t xlat_old_cache;

xlat_cache_block_t xlat_old_cache_ptr;

static void ***xlat_lut;

static void **xlat_lut2; /* second-tier page info */

void xlat_cache_init() 

{

    xlat_new_cache = mmap( NULL, XLAT_NEW_CACHE_SIZE, PROT_EXEC|PROT_READ|PROT_WRITE,

			   MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 );

    xlat_temp_cache = mmap( NULL, XLAT_TEMP_CACHE_SIZE, PROT_EXEC|PROT_READ|PROT_WRITE,

			   MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 );

    xlat_old_cache = mmap( NULL, XLAT_OLD_CACHE_SIZE, PROT_EXEC|PROT_READ|PROT_WRITE,

			   MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 );

    xlat_new_cache_ptr = xlat_new_cache;

    xlat_temp_cache_ptr = xlat_temp_cache;

    xlat_old_cache_ptr = xlat_old_cache;

    xlat_new_create_ptr = xlat_new_cache;

    xlat_lut = mmap( NULL, XLAT_LUT_PAGES*sizeof(void *), PROT_READ|PROT_WRITE,

		     MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);

    memset( xlat_lut, 0, XLAT_LUT_PAGES*sizeof(void *) );

    xlat_flush_cache();

}

/**

 * Reset the cache structure to its default state

 */

void xlat_flush_cache() 

{

    xlat_cache_block_t tmp;

    int i;

    xlat_new_cache_ptr = xlat_new_cache;

    xlat_new_cache_ptr->active = 0;

    xlat_new_cache_ptr->size = XLAT_NEW_CACHE_SIZE - 2*sizeof(struct xlat_cache_block);

    tmp = NEXT(xlat_new_cache_ptr);

    tmp->active = 1;

    tmp->size = 0;

    xlat_temp_cache_ptr = xlat_temp_cache;

    xlat_temp_cache_ptr->active = 0;

    xlat_temp_cache_ptr->size = XLAT_TEMP_CACHE_SIZE - 2*sizeof(struct xlat_cache_block);

    tmp = NEXT(xlat_temp_cache_ptr);

    tmp->active = 1;

    tmp->size = 0;

    xlat_old_cache_ptr = xlat_old_cache;

    xlat_old_cache_ptr->active = 0;

    xlat_old_cache_ptr->size = XLAT_OLD_CACHE_SIZE - 2*sizeof(struct xlat_cache_block);

    tmp = NEXT(xlat_old_cache_ptr);

    tmp->active = 1;

    tmp->size = 0;

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

	if( xlat_lut[i] != NULL ) {

	    memset( xlat_lut[i], 0, XLAT_LUT_PAGE_SIZE );

	}

    }

}

void xlat_flush_page( sh4addr_t address )

{

    int i;

    void **page = xlat_lut[XLAT_LUT_PAGE(address)];

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

	if( IS_ENTRY_POINT(page[i]) ) {

	    BLOCK_FOR_CODE(page[i])->active = 0;

	}

	page[i] = NULL;

    }

}

void *xlat_get_code( sh4addr_t address )

{

    void **page = xlat_lut[XLAT_LUT_PAGE(address)];

    if( page == NULL ) {

	return NULL;

    }

    return page[XLAT_LUT_ENTRY(address)];

}

/**

 * Cut the specified block so that it has the given size, with the remaining data

 * forming a new free block. If the free block would be less than the minimum size,

 * the cut is not performed.

 * @return the next block after the (possibly cut) block.

 */

static inline xlat_cache_block_t xlat_cut_block( xlat_cache_block_t block, int cutsize )

{

    if( block->size > cutsize + MIN_TOTAL_SIZE ) {

	int oldsize = block->size;

	block->size = cutsize;

	xlat_cache_block_t next = NEXT(block);

	next->active = 0;

	next->size = oldsize - cutsize - sizeof(struct xlat_cache_block);

	return next;

    } else {

	return NEXT(block);

    }

}

/**

 * Promote a block in temp space (or elsewhere for that matter) to old space.

 *

 * @param block to promote.

 */

static void xlat_promote_to_old_space( xlat_cache_block_t block )

{

    int allocation = -sizeof(struct xlat_cache_block);

    int size = block->size;

    xlat_cache_block_t curr = xlat_old_cache_ptr;

    xlat_cache_block_t start_block = curr;

    do {

	allocation += curr->size + sizeof(struct xlat_cache_block);

	curr = NEXT(curr);

	if( allocation > size ) {

	    break; /* done */

	}

	if( curr->size == 0 ) { /* End-of-cache Sentinel */

	    /* Leave what we just released as free space and start again from the

	     * top of the cache

	     */

	    start_block->active = 0;

	    start_block->size = allocation;

	    allocation = -sizeof(struct xlat_cache_block);

	    start_block = curr = xlat_old_cache;

	}

    } while(1);

    start_block->active = 1;

    start_block->size = allocation;

    start_block->lut_entry = block->lut_entry;

    *block->lut_entry = &start_block->code;

    memcpy( start_block->code, block->code, block->size );

    xlat_old_cache_ptr = xlat_cut_block(start_block, size );

    if( xlat_old_cache_ptr->size == 0 ) {

	xlat_old_cache_ptr = xlat_old_cache;

    }

}

/**

 * Similarly to the above method, promotes a block to temp space.

 * TODO: Try to combine these - they're nearly identical

 */

void xlat_promote_to_temp_space( xlat_cache_block_t block )

{

    int size = block->size;

    int allocation = -sizeof(struct xlat_cache_block);

    xlat_cache_block_t curr = xlat_temp_cache_ptr;

    xlat_cache_block_t start_block = curr;

    do {

	if( curr->active == BLOCK_USED ) {

	    xlat_promote_to_old_space( curr );

	}

	allocation += curr->size + sizeof(struct xlat_cache_block);

	curr = NEXT(curr);

	if( allocation > size ) {

	    break; /* done */

	}

	if( curr->size == 0 ) { /* End-of-cache Sentinel */

	    /* Leave what we just released as free space and start again from the

	     * top of the cache

	     */

	    start_block->active = 0;

	    start_block->size = allocation;

	    allocation = -sizeof(struct xlat_cache_block);

	    start_block = curr = xlat_temp_cache;

	}

    } while(1);

    start_block->active = 1;

    start_block->size = allocation;

    start_block->lut_entry = block->lut_entry;

    *block->lut_entry = &start_block->code;

    memcpy( start_block->code, block->code, block->size );

    xlat_temp_cache_ptr = xlat_cut_block(start_block, size );

    if( xlat_temp_cache_ptr->size == 0 ) {

	xlat_temp_cache_ptr = xlat_temp_cache;

    }

}

/**

 * Returns the next block in the new cache list that can be written to by the

 * translator. If the next block is active, it is evicted first.

 */

xlat_cache_block_t xlat_start_block( sh4addr_t address )

{

    if( xlat_new_cache_ptr->size == 0 ) {

	xlat_new_cache_ptr = xlat_new_cache;

    }

    if( xlat_new_cache_ptr->active ) {

	xlat_promote_to_temp_space( xlat_new_cache_ptr );

    }

    xlat_new_create_ptr = xlat_new_cache_ptr;

    xlat_new_create_ptr->active = 1;

    xlat_new_cache_ptr = NEXT(xlat_new_cache_ptr);

    /* Add the LUT entry for the block */

    if( xlat_lut[XLAT_LUT_PAGE(address)] == NULL ) {

	xlat_lut[XLAT_LUT_PAGE(address)] =

	    mmap( NULL, XLAT_LUT_PAGE_SIZE, PROT_READ|PROT_WRITE,

		  MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 );

	memset( xlat_lut[XLAT_LUT_PAGE(address)], 0, XLAT_LUT_PAGE_SIZE );

    }

    if( IS_ENTRY_POINT(xlat_lut[XLAT_LUT_PAGE(address)][XLAT_LUT_ENTRY(address)]) ) {

	xlat_cache_block_t oldblock = BLOCK_FOR_CODE(xlat_lut[XLAT_LUT_PAGE(address)][XLAT_LUT_ENTRY(address)]);

	oldblock->active = 0;

    }

    xlat_lut[XLAT_LUT_PAGE(address)][XLAT_LUT_ENTRY(address)] = 

	&xlat_new_create_ptr->code;

    xlat_new_create_ptr->lut_entry = xlat_lut[XLAT_LUT_PAGE(address)] + XLAT_LUT_ENTRY(address);

    return xlat_new_create_ptr;

}

xlat_cache_block_t xlat_extend_block()

{

    if( xlat_new_cache_ptr->size == 0 ) {

	/* Migrate to the front of the cache to keep it contiguous */

	xlat_new_create_ptr->active = 0;

	char *olddata = xlat_new_create_ptr->code;

	int oldsize = xlat_new_create_ptr->size;

	int size = oldsize + MIN_BLOCK_SIZE; /* minimum expansion */

	void **lut_entry = xlat_new_create_ptr->lut_entry;

	int allocation = -sizeof(struct xlat_cache_block);

	xlat_new_cache_ptr = xlat_new_cache;

	do {

	    if( xlat_new_cache_ptr->active ) {

		xlat_promote_to_temp_space( xlat_new_cache_ptr );

	    }

	    allocation += xlat_new_cache_ptr->size + sizeof(struct xlat_cache_block);

	    xlat_new_cache_ptr = NEXT(xlat_new_cache_ptr);

	} while( allocation < size );

	xlat_new_create_ptr = xlat_new_cache;

	xlat_new_create_ptr->active = 1;

	xlat_new_create_ptr->size = allocation;

	xlat_new_create_ptr->lut_entry = lut_entry;

	*lut_entry = &xlat_new_create_ptr->code;

	memmove( xlat_new_create_ptr->code, olddata, oldsize );

    } else {

	if( xlat_new_cache_ptr->active ) {

	    xlat_promote_to_temp_space( xlat_new_cache_ptr );

	}

	xlat_new_create_ptr->size += xlat_new_cache_ptr->size + sizeof(struct xlat_cache_block);

	xlat_new_cache_ptr = NEXT(xlat_new_cache_ptr);

    }

    return xlat_new_create_ptr;

}

void xlat_commit_block( uint32_t destsize, uint32_t srcsize )

{

    void **ptr = xlat_new_create_ptr->lut_entry;

    void **endptr = ptr + (srcsize>>2);

    while( ptr < endptr ) {

	if( *ptr == NULL ) {

	    *ptr = XLAT_LUT_ENTRY_USED;

	}

	ptr++;

    }

    xlat_new_cache_ptr = xlat_cut_block( xlat_new_create_ptr, destsize );

}

void xlat_delete_block( xlat_cache_block_t block ) 

{

    block->active = 0;

    *block->lut_entry = NULL;

}

void xlat_check_cache_integrity( xlat_cache_block_t cache, xlat_cache_block_t ptr, int size )

{

    int foundptr = 0;

    xlat_cache_block_t tail = 

	(xlat_cache_block_t)(((char *)cache) + size - sizeof(struct xlat_cache_block));

    assert( tail->active == 1 );

    assert( tail->size == 0 ); 

    while( cache < tail ) {

	assert( cache->active >= 0 && cache->active <= 2 );

	assert( cache->size >= 0 && cache->size < size );

	if( cache == ptr ) {

	    foundptr = 1;

	}

	cache = NEXT(cache);

    }

    assert( cache == tail );

    assert( foundptr == 1 );

}

void xlat_check_integrity( )

{

    xlat_check_cache_integrity( xlat_new_cache, xlat_new_cache_ptr, XLAT_NEW_CACHE_SIZE );

    xlat_check_cache_integrity( xlat_temp_cache, xlat_temp_cache_ptr, XLAT_TEMP_CACHE_SIZE );

    xlat_check_cache_integrity( xlat_old_cache, xlat_old_cache_ptr, XLAT_OLD_CACHE_SIZE );

}