void prtn_set_addr(byte* bootSec, dword partition_addr)
{
int resSecs; //# of reserved sectors
byte numFATs; //# of FATs
word max_root_entries; /* max# of root dir entries */
word secs_per_FAT;
byte secs_per_clus;
secs_per_clus = bootSec[0x0d];
resSecs = ((bootSec[0x0f]<<8)&0xFF00)|(bootSec[0x0e]&0x00FF);
max_root_entries = ((bootSec[0x12]<<8)&0xFF00)|(bootSec[0x11]&0x00FF);
numFATs = bootSec[0x10];
secs_per_FAT = ((bootSec[0x17]<<8)&0xFF00)|(bootSec[0x16]&0x00FF);
prtn.bytes_per_sec = ((bootSec[0x0c]<<8)&0xFF00)|(bootSec[0x0b]&0x00FF);
prtn.root_dir_addr = partition_addr + ((long)resSecs + (long)secs_per_FAT*(long)numFATs)*(long)(prtn.bytes_per_sec);
prtn.FAT_addr = partition_addr + (long)resSecs*(long)(prtn.bytes_per_sec);
prtn.data_addr = prtn.root_dir_addr + (max_root_entries*32);
prtn.clus_size = prtn.bytes_per_sec * secs_per_clus;
prtn.FAT_size = prtn.bytes_per_sec * secs_per_FAT;
prtn.root_dir_size = max_root_entries * 16;
#if DEBUG
pmsg("Bytes per sector: "); disword_dec(prtn.bytes_per_sec); pmsg("\r\n");
pmsg("Number of reserved sectors: "); disword_dec(resSecs); pmsg("\r\n");
pmsg("root dir at: 0x"); disdword(prtn.root_dir_addr); pmsg("\r\n");
pmsg("FAT at: 0x"); disdword(prtn.FAT_addr); pmsg("\r\n");
pmsg("Data starts at: 0x"); disdword(prtn.data_addr); pmsg("\r\n");
#endif
}
byte read_block(byte* buf,dword addr)
{
int i;
byte c;
byte r1;
if (addr % 512 != 0)
{
#if DEBUG
pmsg("read_block: Address 0x"); disdword(addr);
pmsg("is not aligned to a 512 byte block!\r\n");
#endif
return 0;
}
#if DEBUG
pmsg("Reading block at address 0x"); disdword(addr); pmsg("\r\n");
#endif
r1=CMD(17,addr);
for (i=0;i<50;i++) // wait until the data is found
{
if (r1==0x00) break;
r1 = SPI_Byte(0xFF);
}
if (r1!=0x00)
{
#if DEBUG
pmsg("Read block timed out!\r\n");
#endif
return 0;
}
c = SPI_Byte(0xFF);
while (c!=0xFE)
{
c=SPI_Byte(0xFF);
} // wait for the "data follows" code
for (i=0;i<512;i++)
{
*(buf++)=SPI_Byte(0xFF);
}
c=SPI_Byte(0xFF);
c=SPI_Byte(0xFF); // dummy bytes to clear any queues
return 1;
}
// returns address of first empty root dir entry
dword get_empty_dir_entry(byte* buf)
{
byte i,j;
byte b;
for (i=0;i<32;i++)
{
b = read_block(buf, prtn.root_dir_addr + i*512);
for(j=0;j<16;j++)
{
if(buf[j*32] == 0x00 || buf[j*32] == 0xE5)
{
#if DEBUG
pmsg("found empty direntry at addr: 0x"); disdword(prtn.root_dir_addr + i*512 + j*32); pmsg("\r\n");
#endif
return (prtn.root_dir_addr + i*512 + j*32);
}
}
}
#if DEBUG
pmsg("Failed to find empty directory entry!\r\n");
#endif
return 0;
}
byte create_dir_entry(dir_entry_t* de, char* filename, byte fn_length, byte* buf)
{
dword dir_entry_addr;
memmove(de->filename, filename, fn_length);
de->attributes = NEW_FILE_ATTR;
de->filesize = 0;
memset(de->unused_attr, 0, 14);
dir_entry_addr = get_empty_dir_entry(buf);
#if DEBUG
pmsg("get_direntry returned: 0x"); disdword(dir_entry_addr); pmsg("\r\n");
#endif
if (!dir_entry_addr)
{
#if DEBUG
pmsg("Couldn't find empty direntry!\r\n");
#endif
return 0;
}
de->entry_addr = dir_entry_addr;
// when direntry is allocated cluster is not yet entered
de->first_cluster = 0x0000;
return 1;
}
byte write_block(byte* data, dword addr)
{
byte c;
short i;
if (addr % 512 != 0)
{
#if DEBUG
pmsg("write_block: Address 0x"); disdword(addr);
pmsg("is not aligned to a 512 byte block!\r\n");
#endif
return 0;
}
#if DEBUG
pmsg("Writing block at address 0x"); disdword(addr); pmsg("\r\n");
#endif
if (CMD(24,addr) != 0)
{
#if DEBUG
pmsg("Failed to write block!\r\n");
#endif
return 0;
}
c=SPI_Byte(0xFF); c=SPI_Byte(0xFF); c=SPI_Byte(0xFE); // lead in to actual data
for (i=0;i<BLOCKSIZE;i++) c=SPI_Byte(data[i]);
c=SPI_Byte(0xFF); c=SPI_Byte(0xFF); // dummy before response recieved
c=SPI_Byte(0xFF); c&=0x1F; // bit mask for write error codes
// see http://elm-chan.org/docs/mmc/mmc_e.html
if (c!=0x05)
{
#if DEBUG
pmsg("Failed to write block!\r\n");
#endif
return 0;
}
while (SPI_Byte(0xFF)!=0xFF); // block until write finished
return 1;
}
byte initFAT(byte* buf)
{
byte i;
dword partition_addr;
i = read_block(buf,0);
if(!i){
#if DEBUG
pmsg("read timed out");
#endif
return 0;
}
if (buf[PARTENTRY1 + 0x04] != 0x04 && buf[PARTENTRY1 + 0x04] != 0x06)
{
#if DEBUG
pmsg("drive is not FAT16!\r\n");
#endif
return 0;
}
partition_addr = ((dword)buf[PARTENTRY1 + 0x08] |
(dword)buf[PARTENTRY1 + 0x09] << 8 |
(dword)buf[PARTENTRY1 + 0x0a] << 16 |
(dword)buf[PARTENTRY1 + 0x0b] << 24) * 512;
#if DEBUG
pmsg("partition_addr is: "); disdword(partition_addr); pmsg("\r\n");
#endif
if (!read_block(buf, partition_addr))
{
#if DEBUG
pmsg("couldn't read start of partition!\r\n");
#endif
return 0;
}
prtn_set_addr(buf, partition_addr);
return 1;
}
