mirror of
https://github.com/mist-devel/mist-board.git
synced 2026-02-06 16:14:42 +00:00
89 lines
2.4 KiB
C
89 lines
2.4 KiB
C
/*------------------------------------------------------------------------/
|
|
/ block_io.c
|
|
/
|
|
/ simple block_io layer for MIST board. Can be used as a replacement for
|
|
/ mmc.
|
|
/
|
|
/ This code is in the public domain
|
|
/ (c) 2016 by Till Harbaum
|
|
/--------------------------------------------------------------------------/
|
|
*/
|
|
|
|
#include "diskio.h"
|
|
|
|
// block io registers implemented in block_io.v
|
|
__sfr __at 0x00 LBA0Port;
|
|
__sfr __at 0x01 LBA1Port;
|
|
__sfr __at 0x02 LBA2Port;
|
|
__sfr __at 0x03 LBA3Port;
|
|
__sfr __at 0x04 ControlPort;
|
|
__sfr __at 0x05 DataPort;
|
|
|
|
/*--------------------------------------------------------------------------
|
|
|
|
Public Functions
|
|
|
|
---------------------------------------------------------------------------*/
|
|
|
|
/*-----------------------------------------------------------------------*/
|
|
/* Initialize Disk Drive */
|
|
/*-----------------------------------------------------------------------*/
|
|
|
|
DSTATUS disk_initialize (void) {
|
|
return RES_OK;
|
|
}
|
|
|
|
/*-----------------------------------------------------------------------*/
|
|
/* Read partial sector */
|
|
/*-----------------------------------------------------------------------*/
|
|
|
|
DRESULT disk_readp (
|
|
BYTE *buff, /* Pointer to the read buffer (NULL:Read bytes are forwarded to the stream) */
|
|
DWORD sector, /* Sector number (LBA) */
|
|
UINT offset, /* Byte offset to read from (0..511) */
|
|
UINT count /* Number of bytes to read (ofs + cnt mus be <= 512) */
|
|
)
|
|
{
|
|
static BYTE buffer[512];
|
|
static DWORD buffer_sector = 0xffffffff;
|
|
BYTE *p;
|
|
|
|
// check if sector is already in buffer
|
|
if(buffer_sector != sector) {
|
|
BYTE cnt;
|
|
|
|
// need to load sector into buffer
|
|
|
|
// write 32 bit sector address into block_io controller
|
|
LBA0Port = (sector >> 24) & 0xff;
|
|
LBA1Port = (sector >> 16) & 0xff;
|
|
LBA2Port = (sector >> 8) & 0xff;
|
|
LBA3Port = (sector >> 0) & 0xff;
|
|
|
|
// trigger read
|
|
ControlPort = 0x01;
|
|
|
|
// wait for data to be ready
|
|
while(ControlPort & 1);
|
|
|
|
// read data
|
|
p=buffer;
|
|
for(cnt=0;cnt<128;cnt++) {
|
|
*p++ = DataPort;
|
|
*p++ = DataPort;
|
|
*p++ = DataPort;
|
|
*p++ = DataPort;
|
|
}
|
|
|
|
buffer_sector = sector;
|
|
}
|
|
|
|
// return data from sector buffer
|
|
p = buffer + offset;
|
|
while(count--)
|
|
*buff++ = *p++;
|
|
|
|
return RES_OK;
|
|
}
|
|
|