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Writing data to SD card
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@ifilot
ifilot committed Jul 28, 2024
1 parent 4da7737 commit ca50d16
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Showing 4 changed files with 132 additions and 27 deletions.
122 changes: 102 additions & 20 deletions cartroms/writetest/fat32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,17 @@ uint32_t _current_folder_cluster = 0;
char _basename[9];
char _ext[4];
uint8_t _current_attrib = 0;
uint32_t _last_sector_cache = 0;
uint8_t _last_entry_id_cache = 0;

// file pointer variables
uint32_t _fptr_cluster = 0; // first cluster of a file
uint32_t _fptr_filesize = 0; // stored size of file
uint32_t _fptr_size_allocated = 0; // storage space currently allocated
uint32_t _fptr_pos = 0; // read position
uint32_t _fptr_folder_addr = 0; // cluster address of the folder
uint32_t _fptr_cluster = 0; // first cluster of a file
uint32_t _fptr_filesize = 0; // stored size of file
uint32_t _fptr_size_allocated = 0; // storage space currently allocated
uint32_t _fptr_pos = 0; // read position
uint32_t _fptr_folder_addr = 0; // cluster address of the folder
uint32_t _fptr_entry_sector_addr = 0; // sector address of the file entry
uint8_t _fptr_entry_id = 0; // entry index

/**
* @brief Read the Master Boot Record
Expand Down Expand Up @@ -362,6 +366,8 @@ uint32_t find_in_folder(const char* search, uint8_t which) {
if(!(c & (1 << 4))) {
if(grab_cluster_address_from_fileblock(loc) == _fptr_cluster) {
store_file_metadata(j);
_last_sector_cache = caddr;
_last_entry_id_cache = j;
return _fptr_cluster;
}
}
Expand Down Expand Up @@ -396,7 +402,6 @@ void build_linked_list(uint32_t nextcluster) {
while(nextcluster < 0x0FFFFFF8 && nextcluster != 0 && ctr < F_LL_SIZE) {
_linkedlist[ctr] = nextcluster;
read_sector(_fat_begin_lba + (nextcluster >> 7));
uint8_t item = nextcluster & 0b01111111;
nextcluster = ram_read_uint32_t((nextcluster & 0b01111111) * 4);
ctr++;
}
Expand Down Expand Up @@ -535,14 +540,9 @@ uint32_t allocate_free_cluster(void) {
for(uint8_t i=0; i<128; i++) {
uint32_t cluster = ram_read_uint32_t(ramptr);
if(cluster == 0) {
sprintf(termbuffer, "Found free cluster: %08lX", (ctr << 7) | i);
terminal_printtermbuffer();
ram_write_uint32_t(ramptr, 0x0FFFFFFF);
print("Writing to primary FAT");
write_sector(addr); // write to primary FAT
print("Writing to secondary FAT");
write_sector(addr + _sectors_per_fat); // write to secondary FAT
print("Returning cluster address");
return (ctr << 7) | i;
}
ramptr += 4;
Expand Down Expand Up @@ -572,22 +572,32 @@ uint32_t grab_cluster_address_from_fileblock(uint16_t loc) {
*/
void set_file_pointer(uint32_t folder_addr, uint32_t file_addr) {
// set cluster addresses of files
uint32_t _fptr_folder_addr = folder_addr;
uint32_t _fptr_cluster = file_addr;
_fptr_folder_addr = folder_addr;
_fptr_cluster = file_addr;

// grab total file size
set_current_folder(folder_addr);
find_in_folder("", F_FIND_FILE_ADDR);
_fptr_filesize = _filesize_current_file;
find_in_folder("", F_FIND_FILE_ADDR); // stores metadata
_fptr_filesize = _filesize_current_file; // store file size
_fptr_entry_sector_addr = _last_sector_cache; // store entry sector
_fptr_entry_id = _last_entry_id_cache; // store entry id

// determine allocated file size
build_linked_list(file_addr);

sprintf(termbuffer, "Linked list[0]: %08lX", _linkedlist[0]);
terminal_printtermbuffer();
sprintf(termbuffer, "Linked list[1]: %08lX", _linkedlist[1]);
terminal_printtermbuffer();

uint8_t ctr = 0;
_fptr_size_allocated = 0;
while(_linkedlist[ctr] != 0xFFFFFFFF && ctr < F_LL_SIZE) {
_fptr_size_allocated += _sectors_per_cluster * _bytes_per_sector;
ctr++;
}
ctr++;
_fptr_size_allocated = ctr * _sectors_per_cluster * _bytes_per_sector;
sprintf(termbuffer, "Allocated size: %08lX KiB", _fptr_size_allocated);
terminal_printtermbuffer();

// reset pointer positions
_fptr_pos = 0;
Expand All @@ -611,10 +621,29 @@ void set_file_pointer(uint32_t folder_addr, uint32_t file_addr) {
* @param nrbytes number of bytes to write
*/
void write_to_file(uint16_t extramptr, uint16_t nrbytes) {
if(_fptr_cluster == 0) {
print_error("No file pointer is set");
}

// calculate final position after writing
uint32_t finalpos = _fptr_pos + nrbytes;

sprintf(termbuffer, "Final position: %08lX", finalpos);
terminal_printtermbuffer();

sprintf(termbuffer, "Allocated size: %08lX", _fptr_size_allocated);
terminal_printtermbuffer();

// check if allocatable size needs to be expanded and do so if necessary
if(finalpos > _fptr_size_allocated) {
// allocate more clusters
print("Allocating more clusters");
// uint32_t bytes_per_cluster = _bytes_per_sector * _sectors_per_cluster;
// uint32_t required_size = finalpos - _fptr_size_allocated;
// uint8_t newclusters = required_size / bytes_per_cluster;
// if(newclusters == 0) {
// newclusters++;
// }
// allocate_clusters(newclusters);
}

// build the linked list for the file
Expand All @@ -624,7 +653,6 @@ void write_to_file(uint16_t extramptr, uint16_t nrbytes) {
uint32_t blockpos = 0;
uint32_t nextblockpos = 0;
uint16_t bytes_to_write = 0;
uint32_t sector_addr = 0;

// loop over the clusters
uint8_t ctr = 0; // cluster counter
Expand All @@ -635,6 +663,9 @@ void write_to_file(uint16_t extramptr, uint16_t nrbytes) {
// set position of next block
nextblockpos = blockpos + _bytes_per_sector;

sprintf(termbuffer, "Sector: %02X", i);
terminal_printtermbuffer();

// check if the write position is in this current block
if(_fptr_pos >= blockpos && _fptr_pos < nextblockpos) {
// determine how many bytes need to be written in this block
Expand All @@ -645,14 +676,26 @@ void write_to_file(uint16_t extramptr, uint16_t nrbytes) {
}

// determine sector address
sector_addr = calculate_sector_address(_linkedlist[ctr], i);
uint32_t sector_addr = calculate_sector_address(_linkedlist[ctr], i);

// read data from sector in SDCACHE0
read_sector(sector_addr);

terminal_hexdump(SDCACHE0, 2, DUMP_EXTRAM);

sprintf(termbuffer, "Writing bytes: %04X", bytes_to_write);
terminal_printtermbuffer();

sprintf(termbuffer, "Transfer from: %04X", extramptr);
terminal_printtermbuffer();
sprintf(termbuffer, "Transfer to: %04X", SDCACHE0 + (_fptr_pos - blockpos));
terminal_printtermbuffer();

// copy new data into sector
ram_transfer(extramptr, SDCACHE0 + (_fptr_pos - blockpos), bytes_to_write);

terminal_hexdump(SDCACHE0, 2, DUMP_EXTRAM);

// write sector from SDCACHE0
write_sector(sector_addr);

Expand All @@ -663,6 +706,16 @@ void write_to_file(uint16_t extramptr, uint16_t nrbytes) {

// check if all data has been written, if so, stop function
if(finalpos == _fptr_pos) {

print("Data is written");

// store updated file size if the file has grown in size
if(finalpos > _fptr_filesize) {
read_sector(_fptr_entry_sector_addr);
ram_write_uint32_t(SDCACHE0 + _fptr_entry_id * 32 + 28, finalpos);
write_sector(_fptr_entry_sector_addr);
}

return;
}

Expand All @@ -671,4 +724,33 @@ void write_to_file(uint16_t extramptr, uint16_t nrbytes) {
}
ctr++;
}
}

/**
* @brief Allocate for file pointer additional clusters
*/
void allocate_clusters(uint8_t nr_of_clusters) {
// build the linked list for the file
build_linked_list(_fptr_cluster);
uint8_t ctr = 0; // cluster counter
while(_linkedlist[ctr] != 0xFFFFFFFF && ctr < F_LL_SIZE) {ctr++;}
for(uint8_t i=0; i<nr_of_clusters; i++) {
_linkedlist[ctr] = allocate_free_cluster();
update_pointer_next_cluster(_linkedlist[ctr-1], _linkedlist[ctr]);
ctr++;
}
}

/**
* @brief Update cluster pointer
*
* @param src // source cluster
* @param des // destination cluster
*/
void update_pointer_next_cluster(uint32_t src, uint32_t des) {
uint32_t addr = _fat_begin_lba + (src >> 7);
read_sector(addr);
ram_write_uint32_t((src & 0b01111111) * 4, des);
write_sector(addr);
write_sector(addr + _sectors_per_fat);
}
14 changes: 14 additions & 0 deletions cartroms/writetest/fat32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ extern uint32_t _cluster_begin_lba;
extern uint32_t _lba_addr_root_dir;
extern uint32_t _linkedlist[F_LL_SIZE];
extern uint32_t _current_folder_cluster;
extern uint32_t _fptr_cluster;

// global variables for currently active file or folder
extern uint32_t _filesize_current_file;
Expand Down Expand Up @@ -179,4 +180,17 @@ inline void set_current_folder(uint32_t folder_addr) {
*/
void write_to_file(uint16_t extramptr, uint16_t nrbytes);

/**
* @brief Allocate for file pointer additional clusters
*/
void allocate_clusters(uint8_t nr_of_clusters);

/**
* @brief Update cluster pointer
*
* @param src // source cluster
* @param des // destination cluster
*/
void update_pointer_next_cluster(uint32_t src, uint32_t des);

#endif // _FAT32_H
18 changes: 14 additions & 4 deletions cartroms/writetest/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -59,16 +59,26 @@ void main(void) {
read_folder(-1, 0);

// proceed to create new file
uint8_t res = create_new_file("BEVER002TXT");
uint8_t res = create_new_file("BEVER003TXT");
sprintf(termbuffer, "File creation result: %02X", res);
terminal_printtermbuffer();

read_folder(-1, 0);

set_current_folder(folder_addr);
uint32_t file_addr = find_in_folder("BEVER001TXT", F_FIND_FOLDER_NAME);
uint32_t file_addr = find_in_folder("BEVER003TXT", F_FIND_FILE_NAME);

set_file_pointer(folder_addr, file_addr);

// allocate some writeable data
for(uint16_t i=0; i<256; i++) {
ram_write_uint8_t(SDCACHE1+i, i);
}

terminal_hexdump(SDCACHE1, 4, DUMP_EXTRAM);

for(uint8_t j=0; j<128; j++) {
write_to_file(SDCACHE1, 256);
}

} else {
print_error("No folder DUMPS found in root dir.");
}
Expand Down
5 changes: 2 additions & 3 deletions cartroms/writetest/ram.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -132,11 +132,10 @@ _ram_read_uint32_t:
_ram_write_uint8_t:
pop de ; return address
pop hl ; ramptr
call _set_ram_address
dec sp ; decrement sp for 1-byte argument
pop bc ; byte to write (stored in b)
pop af ; byte to write (stored in b)
push de ; push return address back onto stack
call _set_ram_address
ld a,b
out (RAM_IO), a
ret

Expand Down

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