adds a dynamic ramdisk. Right now its not used. It can be use to save temporary files e.g. to extract of opening.bnr

This commit is contained in:
ardi@ist-einmalig.de 2009-07-26 12:12:04 +00:00
parent 47989619cd
commit 5547e9a2ec
2 changed files with 237 additions and 0 deletions

198
source/ramdisc/ramdisc.cpp Normal file
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#include <string.h>
#include "ramdisc.h"
static inline u16 u8array_to_u16 (const u8* item, int offset)
{
return ( item[offset] | (item[offset + 1] << 8));
}
static inline u32 u8array_to_u32 (const u8* item, int offset)
{
return ( item[offset] | (item[offset + 1] << 8) | (item[offset + 2] << 16) | (item[offset + 3] << 24) );
}
static inline void u16_to_u8array (u8* item, int offset, u16 value)
{
item[offset] = (u8) value; item[offset + 1] = (u8)(value >> 8);
}
static inline void u32_to_u8array (u8* item, int offset, u32 value)
{
item[offset] = (u8) value;
item[offset + 1] = (u8)(value >> 8);
item[offset + 2] = (u8)(value >> 16);
item[offset + 3] = (u8)(value >> 24);
}
class padding
{
public:
padding(u32 Start, u32 NumSectors)
{
start = Start;
end = Start + NumSectors;
data = new u8[NumSectors*512];
next = 0;
}
~padding() { delete [] data;}
u32 start;
u32 end;
u8 *data;
padding *next;
};
static u32 __ramdisk_sectorsOfPadding;
static padding *__ramdisk_data_start;
static padding *__ramdisk_data_end;
static bool __ramdisk_IsInserted(void)
{
return __ramdisk_data_start!=NULL;
}
//forward decleration
static bool __ramdisk_WriteSectors(size_t Sector, size_t numSectors, u8 *Buffer);
bool initRAMDisc(u32 Size, u32 Padding)
{
if(__ramdisk_data_start) return true; // is init
if(Size > 16*1024*1024) Size = 16*1024*1024; // maximum 16 MB
if(Size < 16*1024) Size = 16*1024; // minimum 16 MB
if(Padding > Size) Padding = Size; // Padding maximum =Disksize
if(Padding < 4*1024) Padding = 4*1024; // Padding minimum 4kB
__ramdisk_sectorsOfPadding = Padding/512;
__ramdisk_data_start = __ramdisk_data_end = new padding(0, __ramdisk_sectorsOfPadding);
if(!__ramdisk_data_start) return false;
// FAT12 Formatieren
u8 sector[512] = {0, };
sector[0x00d] = 2; /*BPB_sectorsPerCluster*/
sector[0x00e] = 1; /*BPB_reservedSectors*/
sector[0x010] = 1; /*BPB_numFATs*/
u16_to_u8array (sector, 0x011, 48); /*BPB_rootEntries*/
int num_sectors = Size/512;
u16_to_u8array (sector, 0x013, num_sectors); /*BPB_numSectorsSmall*/
int num_clusters = (num_sectors-1-3) /2;
int sectors_per_fat = (num_clusters * 3 + 1023) /1024;
u16_to_u8array (sector, 0x016, sectors_per_fat); /*BPB_sectorsPerFAT*/
//u32_to_u8array (sector, 0x020, Size/512); /*BPB_numSectors*/
sector[0x036] = 'F';
sector[0x037] = 'A';
sector[0x038] = 'T';
sector[0x1fe] = 0x55;
sector[0x1ff] = 0xaa;
if(!__ramdisk_WriteSectors(0, 1, sector))
goto error;
memset(sector, 0, 512);
// clear FAT & rootDir
for(int i=1; i<= sectors_per_fat+3/*sectors_per_rootDir*/; i++)
if(!__ramdisk_WriteSectors(1, 1, sector))
goto error;
return true;
error:
delete __ramdisk_data_start;
__ramdisk_data_start = 0;
return false;
}
void exitRAMDisc()
{
while(__ramdisk_data_start)
{
padding *tmp = __ramdisk_data_start;
__ramdisk_data_start = __ramdisk_data_start->next;
delete tmp;
}
}
static u8 *__ramdisk_findSector(size_t Sector, size_t *Sectors)
{
if(__ramdisk_data_start==NULL) return NULL;
for(padding *tmp = __ramdisk_data_start; tmp; tmp=tmp->next)
{
if(tmp->start <= Sector && tmp->end >= Sector)
{
if(Sectors) *Sectors = 1+tmp->end-Sector;
return &(tmp->data[(Sector-tmp->start)*512]);
}
}
// not found -> add padding
__ramdisk_data_end->next = new padding((Sector/__ramdisk_sectorsOfPadding)*__ramdisk_sectorsOfPadding, __ramdisk_sectorsOfPadding);
if(__ramdisk_data_end->next)
{
__ramdisk_data_end = __ramdisk_data_end->next;
return &( __ramdisk_data_end->data[(Sector-__ramdisk_data_end->start)*512]);
}
return 0;
}
static bool __ImplizitInit = false;
static bool __ramdisk_Startup(void)
{
if(!__ramdisk_IsInserted())
{
// Std=8MB/64kB Padding
return (__ImplizitInit = initRAMDisc(8*1024*1024, 64 * 1024));
}
return true;
}
static bool __ramdisk_ReadSectors(size_t Sector, size_t numSectors, u8 *Buffer)
{
size_t num_sectors;
while(numSectors)
{
if(u8 *buff = __ramdisk_findSector(Sector,&num_sectors))
{
if(num_sectors > numSectors) num_sectors = numSectors;
memcpy(Buffer, buff, num_sectors * 512);
numSectors -= num_sectors;
Buffer+= num_sectors;
}
else
return false;
}
return true;
}
static bool __ramdisk_WriteSectors(size_t Sector, size_t numSectors, u8 *Buffer)
{
size_t num_sectors;
while(numSectors)
{
if(u8 *buff = __ramdisk_findSector(Sector,&num_sectors))
{
if(num_sectors > numSectors) num_sectors = numSectors;
memcpy(buff, Buffer, num_sectors * 512);
numSectors -= num_sectors;
Buffer+= num_sectors;
}
else
return false;
}
return true;
}
static bool __ramdisk_ClearStatus(void)
{
return true;
}
static bool __ramdisk_Shutdown(void)
{
if(__ImplizitInit)
{
__ImplizitInit = false;
exitRAMDisc();
}
return true;
}
const DISC_INTERFACE __io_ramdisk = {
DEVICE_TYPE_RAM_DISK,
FEATURE_MEDIUM_CANREAD | FEATURE_MEDIUM_CANWRITE | 0x1000,
(FN_MEDIUM_STARTUP)&__ramdisk_Startup,
(FN_MEDIUM_ISINSERTED)&__ramdisk_IsInserted,
(FN_MEDIUM_READSECTORS)&__ramdisk_ReadSectors,
(FN_MEDIUM_WRITESECTORS)&__ramdisk_WriteSectors,
(FN_MEDIUM_CLEARSTATUS)&__ramdisk_ClearStatus,
(FN_MEDIUM_SHUTDOWN)&__ramdisk_Shutdown
};

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source/ramdisc/ramdisc.h Normal file
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#ifndef __RAMDISC_H
#define __RAMDISC_H
#include <gctypes.h>
#include <ogc/disc_io.h>
#define DEVICE_TYPE_RAM_DISK (('R'<<24)|('A'<<16)|('M'<<8)|'D')
extern const DISC_INTERFACE __io_ramdisk;
/*
initRamDisc initialize a dynamic RAM-disc.
Size is the maximum disksize in a range from 16kB up to 16MB
Padding is the size of blocks to be allocate in a range from 4kB up to Disksize
The RAM-disc is formated in FAT12.
*/
bool initRAMDisc(u32 Size, u32 Padding);
/*
exitRAMDisc destroy all datas
*/
void exitRAMDisc();
/*
NOTE:
if the RAM-disc allready initialized, then initRAMDisc returns with "true" without reinitialize it with the new parameters.
__io_ramdisk.startup() initialize a ramdisc of 8MB with a padding of 64kB
__io_ramdisk.shutdown () will only destroy the RAM-disk, if they from __io_ramdisk.startup () was initialized
if the ramdisc initialized from initRamDisc, then you can remount the filesystem without lost all datas
Example:
fatMount("RAM", &__io_ramdisk, 0, 0, 0);
...
fopen("RAM:/file", ...);
*/
#endif /*__RAMDISC_H*/