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New cache algorithm

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@526 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Linus Nielsen Feltzing 2002-05-09 21:27:49 +00:00
parent 063a85c66f
commit 114fce01dd
1 changed files with 71 additions and 20 deletions
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91
firmware/drivers/fat.c
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@ -126,11 +126,17 @@ static int create_dos_name(unsigned char *name, unsigned char *newname);
/* global FAT info struct */
struct bpb fat_bpb;
/* fat cache */
static unsigned char *fat_cache[256];
#ifdef DISK_WRITE
static int fat_cache_dirty[256];
#endif
#define FAT_CACHE_SIZE 0x20
#define FAT_CACHE_MASK (FAT_CACHE_SIZE-1)
struct fat_cache_entry
{
unsigned char *ptr;
int secnum;
int dirty;
};
struct fat_cache_entry fat_cache[FAT_CACHE_SIZE];
/* sectors cache for longname use */
static unsigned char lastsector[SECTOR_SIZE];
@ -173,6 +179,19 @@ int fat_mount(int startsector)
int err;
int datasec;
int countofclusters;
int i;
/* Clear the cache. Be aware! The bss section MUST have been cleared
at boot. Otherwise we will free() garbage pointers here */
for(i = 0;i < FAT_CACHE_SIZE;i++)
{
if(fat_cache[i].ptr)
{
free(fat_cache[i].ptr);
}
fat_cache[i].secnum = 8; /* We use a "safe" sector just in case */
fat_cache[i].dirty = 0;
}
/* Read the sector */
err = ata_read_sectors(startsector,1,buf);
@ -308,9 +327,34 @@ static int bpb_is_sane(void)
static void *cache_fat_sector(int secnum)
{
int cache_index = secnum & FAT_CACHE_MASK;
unsigned char *sec;
sec = fat_cache[secnum];
sec = fat_cache[cache_index].ptr;
/* Delete the cache entry if it isn't the sector we want */
if(sec && fat_cache[cache_index].secnum != secnum)
{
#ifdef WRITE
/* Write back if it is dirty */
if(fat_cache[cache_index].dirty)
{
if(ata_write_sectors(secnum + fat_bpb.bpb_rsvdseccnt +
fat_bpb.startsector, 1, sec))
{
panic("cache_fat_sector() - Could"
" not write sector %d\n",
secnum);
}
}
free(sec);
fat_cache[cache_index].ptr = NULL;
fat_cache[cache_index].secnum = 8; /* Normally an unused sector */
fat_cache[cache_index].dirty = 0;
#endif
}
/* Load the sector if it is not cached */
if(!sec)
{
@ -328,7 +372,8 @@ static void *cache_fat_sector(int secnum)
free(sec);
return NULL;
}
fat_cache[secnum] = sec;
fat_cache[cache_index].ptr = sec;
fat_cache[cache_index].secnum = secnum;
}
return sec;
}
@ -354,7 +399,9 @@ static int update_entry(int entry, unsigned int val)
return -1;
}
fat_cache_dirty[thisfatsecnum] = 1;
/* We can safely assume that the correct sector is in the cache,
so we mark it dirty without checking the sector number */
fat_cache[thisfatsecnum & FAT_CACHE_MASK].dirty = 1;
/* don't change top 4 bits */
sec[thisfatentoffset/sizeof(int)] &= 0xf000000;
@ -406,36 +453,40 @@ static int flush_fat(struct bpb *bpb)
int i;
int err;
unsigned char *sec;
int secnum;
int fatsz;
unsigned short d, t;
char m;
fatsz = fat_bpb.fatsize;
for(i = 0;i < 256;i++)
for(i = 0;i < FAT_CACHE_SIZE;i++)
{
if(fat_cache[i] && fat_cache_dirty[i])
if(fat_cache[i].ptr && fat_cache[i].dirty)
{
DEBUGF("Flushing FAT sector %d\n", i);
sec = fat_cache[i];
err = ata_write_sectors(i + fat_bpb.bpb_rsvdseccnt + fat_bpb.startsector,
1,sec);
secnum = fat_cache[i].secnum + fat_bpb.bpb_rsvdseccnt +
fat_bpb.startsector;
DEBUGF("Flushing FAT sector %d\n", secnum);
sec = fat_cache[i].ptr;
/* Write to the first FAT */
err = ata_write_sectors(secnum, 1, sec);
if(err)
{
DEBUGF( "flush_fat() - Couldn't write"
" sector (%d)\n", i + fat_bpb.bpb_rsvdseccnt);
" sector (%d)\n", secnum);
return -1;
}
err = ata_write_sectors(i + fat_bpb.bpb_rsvdseccnt + fatsz +
fat_bpb.startsector,
1,sec);
/* Write to the second FAT */
err = ata_write_sectors(secnum + fatsz, 1, sec);
if(err)
{
DEBUGF( "flush_fat() - Couldn't write"
" sector (%d)\n", i + fat_bpb.bpb_rsvdseccnt + fatsz);
" sector (%d)\n", secnum + fatsz);
return -1;
}
fat_cache_dirty[i] = 0;
fat_cache[i].dirty = 0;
}
}