+++ /dev/null
-/*
- * Acess2 Kernel
- * - IO Cache
- *
- * By thePowersGang (John Hodge)
- */
-#define DEBUG 0
-#include <acess.h>
-#include <iocache.h>
-
-// === TYPES ===
-typedef struct sIOCache_Ent tIOCache_Ent;
-
-// === STRUCTURES ===
-struct sIOCache_Ent
-{
- tIOCache_Ent *Next;
- Uint64 Num;
- Sint64 LastAccess;
- Sint64 LastWrite;
- Uint8 Data[];
-};
-
-struct sIOCache
-{
- tIOCache *Next;
- int SectorSize;
- tMutex Lock;
- int Mode;
- Uint32 ID;
- tIOCache_WriteCallback Write;
- int CacheSize;
- int CacheUsed;
- tIOCache_Ent *Entries;
-};
-
-// === GLOBALS ===
-tShortSpinlock glIOCache_Caches;
-tIOCache *gIOCache_Caches = NULL;
- int giIOCache_NumCaches = 0;
-
-// === CODE ===
-/**
- * \fn tIOCache *IOCache_Create( tIOCache_WriteCallback Write, Uint32 ID, int SectorSize, int CacheSize )
- * \brief Creates a new IO Cache
- */
-tIOCache *IOCache_Create( tIOCache_WriteCallback Write, Uint32 ID, int SectorSize, int CacheSize )
-{
- tIOCache *ret = calloc( 1, sizeof(tIOCache) );
-
- // Sanity Check
- if(!ret) return NULL;
-
- // Fill Structure
- ret->SectorSize = SectorSize;
- ret->Mode = IOCACHE_WRITEBACK;
- ret->ID = ID;
- ret->Write = Write;
- ret->CacheSize = CacheSize;
-
- // Append to list
- SHORTLOCK( &glIOCache_Caches );
- ret->Next = gIOCache_Caches;
- gIOCache_Caches = ret;
- SHORTREL( &glIOCache_Caches );
-
- // Return
- return ret;
-}
-
-/**
- * \fn int IOCache_Read( tIOCache *Cache, Uint64 Sector, void *Buffer )
- * \brief Read from a cached sector
- */
-int IOCache_Read( tIOCache *Cache, Uint64 Sector, void *Buffer )
-{
- tIOCache_Ent *ent;
-
- ENTER("pCache XSector pBuffer", Cache, Sector, Buffer);
-
- // Sanity Check!
- if(!Cache || !Buffer) {
- LEAVE('i', -1);
- return -1;
- }
-
- // Lock
- Mutex_Acquire( &Cache->Lock );
- if(Cache->CacheSize == 0) {
- Mutex_Release( &Cache->Lock );
- LEAVE('i', -1);
- return -1;
- }
-
- // Search the list
- for( ent = Cache->Entries; ent; ent = ent->Next )
- {
- // Have we found what we are looking for?
- if( ent->Num == Sector ) {
- memcpy(Buffer, ent->Data, Cache->SectorSize);
- ent->LastAccess = now();
- Mutex_Release( &Cache->Lock );
- LEAVE('i', 1);
- return 1;
- }
- // It's a sorted list, so as soon as we go past `Sector` we know
- // it's not there
- if(ent->Num > Sector) break;
- }
-
- Mutex_Release( &Cache->Lock );
- LEAVE('i', 0);
- return 0;
-}
-
-/**
- * \fn int IOCache_Add( tIOCache *Cache, Uint64 Sector, void *Buffer )
- * \brief Cache a sector
- */
-int IOCache_Add( tIOCache *Cache, Uint64 Sector, void *Buffer )
-{
- tIOCache_Ent *ent, *prev;
- tIOCache_Ent *new;
- tIOCache_Ent *oldest = NULL, *oldestPrev;
-
- // Sanity Check!
- if(!Cache || !Buffer)
- return -1;
-
- // Lock
- Mutex_Acquire( &Cache->Lock );
- if(Cache->CacheSize == 0) {
- Mutex_Release( &Cache->Lock );
- return -1;
- }
-
- // Search the list
- prev = (tIOCache_Ent*)&Cache->Entries;
- for( ent = Cache->Entries; ent; prev = ent, ent = ent->Next )
- {
- // Is it already here?
- if( ent->Num == Sector ) {
- Mutex_Release( &Cache->Lock );
- return 0;
- }
-
- // Check if we have found the oldest entry
- if( !oldest || oldest->LastAccess > ent->LastAccess ) {
- oldest = ent;
- oldestPrev = prev;
- }
-
- // Here we go!
- if(ent->Num > Sector)
- break;
- }
-
- // Create the new entry
- new = malloc( sizeof(tIOCache_Ent) + Cache->SectorSize );
- new->Next = ent;
- new->Num = Sector;
- new->LastAccess = now();
- new->LastWrite = 0; // Zero is special, it means unmodified
- memcpy(new->Data, Buffer, Cache->SectorSize);
-
- // Have we reached the maximum cached entries?
- if( Cache->CacheUsed == Cache->CacheSize )
- {
- tIOCache_Ent *savedPrev = prev;
- oldestPrev = (tIOCache_Ent*)&Cache->Entries;
- // If so, search for the least recently accessed entry
- for( ; ent; prev = ent, ent = ent->Next )
- {
- // Check if we have found the oldest entry
- if( !oldest || oldest->LastAccess > ent->LastAccess ) {
- oldest = ent;
- oldestPrev = prev;
- }
- }
- // Remove from list, write back and free
- oldestPrev->Next = oldest->Next;
- if(oldest->LastWrite && Cache->Mode != IOCACHE_VIRTUAL)
- Cache->Write(Cache->ID, oldest->Num, oldest->Data);
- free(oldest);
-
- // Decrement the used count
- Cache->CacheUsed --;
-
- // Restore `prev`
- prev = savedPrev;
- }
-
- // Append to list
- prev->Next = new;
- Cache->CacheUsed ++;
-
- // Release Spinlock
- Mutex_Release( &Cache->Lock );
-
- // Return success
- return 1;
-}
-
-/**
- * \fn int IOCache_Write( tIOCache *Cache, Uint64 Sector, void *Buffer )
- * \brief Read from a cached sector
- */
-int IOCache_Write( tIOCache *Cache, Uint64 Sector, void *Buffer )
-{
- tIOCache_Ent *ent;
-
- // Sanity Check!
- if(!Cache || !Buffer)
- return -1;
- // Lock
- Mutex_Acquire( &Cache->Lock );
- if(Cache->CacheSize == 0) {
- Mutex_Release( &Cache->Lock );
- return -1;
- }
-
- // Search the list
- for( ent = Cache->Entries; ent; ent = ent->Next )
- {
- // Have we found what we are looking for?
- if( ent->Num == Sector ) {
- memcpy(ent->Data, Buffer, Cache->SectorSize);
- ent->LastAccess = ent->LastWrite = now();
-
- if(Cache->Mode == IOCACHE_WRITEBACK) {
- Cache->Write(Cache->ID, Sector, Buffer);
- ent->LastWrite = 0;
- }
-
- Mutex_Release( &Cache->Lock );
- return 1;
- }
- // It's a sorted list, so as soon as we go past `Sector` we know
- // it's not there
- if(ent->Num > Sector) break;
- }
-
- Mutex_Release( &Cache->Lock );
- return 0;
-}
-
-/**
- * \fn void IOCache_Flush( tIOCache *Cache )
- * \brief Flush a cache
- */
-void IOCache_Flush( tIOCache *Cache )
-{
- tIOCache_Ent *ent;
-
- if( Cache->Mode == IOCACHE_VIRTUAL ) return;
-
- // Lock
- Mutex_Acquire( &Cache->Lock );
- if(Cache->CacheSize == 0) {
- Mutex_Release( &Cache->Lock );
- return;
- }
-
- // Write All
- for( ent = Cache->Entries; ent; ent = ent->Next )
- {
- Cache->Write(Cache->ID, ent->Num, ent->Data);
- ent->LastWrite = 0;
- }
-
- Mutex_Release( &Cache->Lock );
-}
-
-/**
- * \fn void IOCache_Destroy( tIOCache *Cache )
- * \brief Destroy a cache
- */
-void IOCache_Destroy( tIOCache *Cache )
-{
- tIOCache_Ent *ent, *prev = NULL;
-
- // Lock
- Mutex_Acquire( &Cache->Lock );
- if(Cache->CacheSize == 0) {
- Mutex_Release( &Cache->Lock );
- return;
- }
-
- // Free All
- for(ent = Cache->Entries;
- ent;
- prev = ent, ent = ent->Next, free(prev) )
- {
- if( Cache->Mode != IOCACHE_VIRTUAL )
- {
- Cache->Write(Cache->ID, ent->Num, ent->Data);
- ent->LastWrite = 0;
- }
- }
-
- Cache->CacheSize = 0;
-
- Mutex_Release( &Cache->Lock );
-
- // Remove from list
- SHORTLOCK( &glIOCache_Caches );
- {
- tIOCache *ent;
- tIOCache *prev = (tIOCache*)&gIOCache_Caches;
- for(ent = gIOCache_Caches;
- ent;
- prev = ent, ent = ent->Next )
- {
- if(ent == Cache) {
- prev->Next = ent->Next;
- break;
- }
- }
- }
- SHORTREL( &glIOCache_Caches );
-
- free(Cache);
-}
git.ucc.asn.au / tpg / acess2.git / blobdiff
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