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/*
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* cache.cpp - simple floppy/cd cache for Win32
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*
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* Basilisk II (C) 1997-2004 Christian Bauer
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*
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* Windows platform specific code copyright (C) Lauri Pesonen
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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Note that this is particularly silly cache code
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and doesn't even use hash buckets. It is sufficient
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for floppies and maybe emulated cd's but that's it.
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*/
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#include "sysdeps.h"
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#include "windows.h"
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#include "cache.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifdef _DEBUG
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#define new DEBUG_NEW
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#undef THIS_FILE
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static char THIS_FILE[] = __FILE__;
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#endif
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void cache_clear( cachetype *cptr )
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{
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if(cptr->inited) {
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cptr->res_count = 0;
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memset( cptr->LRU, 0, NBLOCKS * sizeof(int) );
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}
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}
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static int init( cachetype *cptr, int sector_size )
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{
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cache_clear( cptr );
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cptr->sector_size = sector_size;
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cptr->blocks = (char *)VirtualAlloc(
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NULL, NBLOCKS*sector_size,
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MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE );
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cptr->block = (int *)VirtualAlloc(
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NULL, NBLOCKS*sizeof(int),
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MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE );
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cptr->LRU = (DWORD *)VirtualAlloc(
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NULL, NBLOCKS*sizeof(DWORD),
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MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE );
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return(cptr->blocks != NULL);
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}
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static void final( cachetype *cptr )
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{
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if(cptr->blocks) {
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VirtualFree( cptr->blocks, 0, MEM_RELEASE );
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cptr->blocks = 0;
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}
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if(cptr->block) {
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VirtualFree( cptr->block, 0, MEM_RELEASE );
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cptr->block = 0;
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}
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if(cptr->LRU) {
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VirtualFree( cptr->LRU, 0, MEM_RELEASE );
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cptr->LRU = 0;
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}
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cptr->inited = 0;
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}
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void cache_init( cachetype *cptr )
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{
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cptr->inited = 0;
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}
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void cache_final( cachetype *cptr )
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{
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if(cptr->inited) {
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final( cptr );
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cptr->inited = 0;
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}
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}
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static int in_cache( cachetype *cptr, int block )
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{
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int i;
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for(i=cptr->res_count-1; i>=0; i--) {
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if(cptr->block[i] == block) return(i);
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}
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return(-1);
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}
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static int get_LRU( cachetype *cptr )
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{
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int i, result = 0;
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DWORD mtime = cptr->LRU[0];
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for(i=1; i<NBLOCKS; i++) {
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if(cptr->LRU[i] < mtime) {
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mtime = cptr->LRU[i];
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result = i;
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}
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}
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return(result);
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}
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void cache_put( cachetype *cptr, int block, char *buf, int ss )
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{
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int inx;
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if(!cptr->inited) {
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if(!init(cptr,ss)) return;
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cptr->inited = 1;
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}
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inx = in_cache( cptr, block );
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if(inx < 0) {
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if(cptr->res_count == NBLOCKS) {
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inx = get_LRU( cptr );
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} else {
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inx = cptr->res_count++;
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}
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cptr->block[inx] = block;
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}
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cptr->LRU[inx] = GetTickCount();
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memcpy( cptr->blocks + inx * ss, buf, ss );
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}
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int cache_get( cachetype *cptr, int block, char *buf )
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{
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int inx;
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if(!cptr->inited) return(0);
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inx = in_cache( cptr, block );
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if(inx >= 0) {
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memcpy( buf, cptr->blocks + inx * cptr->sector_size, cptr->sector_size );
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return(1);
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} else {
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return(0);
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}
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}
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void cache_remove( cachetype *cptr, int block, int ss )
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{
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int inx, from;
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if(!cptr->inited) {
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if(!init(cptr,ss)) return;
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cptr->inited = 1;
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}
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inx = in_cache( cptr, block );
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if(inx >= 0) {
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if(cptr->res_count > 1) {
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from = cptr->res_count-1;
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cptr->block[inx] = cptr->block[from];
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cptr->LRU[inx] = cptr->LRU[from];
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memcpy(
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cptr->blocks + inx * cptr->sector_size,
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cptr->blocks + from * cptr->sector_size,
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cptr->sector_size
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);
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}
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cptr->res_count--;
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}
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}
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#ifdef __cplusplus
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} // extern "C"
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#endif
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