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mem-ffs.c
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mem-ffs.c
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/*
IBEX UK LTD http://www.ibexuk.com
Electronic Product Design Specialists
RELEASED SOFTWARE
The MIT License (MIT)
Copyright (c) 2013, IBEX UK Ltd, http://ibexuk.com
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
//Project Name: FAT FILING SYSTEM FAT16 & FAT 32 DRIVER
//FAT FILING SYSTEM DRIVER C CODE FILE
#include "main.h" //Global data type definitions (see https://github.com/ibexuk/C_Generic_Header_File )
#define FFS_C
#include "mem-ffs.h"
#include "mem-mmcsd.h"
//*******************************
//*******************************
//********** OPEN FILE **********
//*******************************
//*******************************
//For ease of use this driver does not differentiate between text and binary mode. You may open a file in either mode (or
//neither) and all file operations will be exactly the same (basically is if the file was opened in binary mode. LF characters
//will not be converted to a pair CRLF characters and vice versa. This makes using functions like fseek much simpler and avoids
//operating system difference issues. (If you are not aware there is no difference between a binary file and a text file - the
//difference is in how the operating system chooses to handle text files)
//
//filename
// Only 8 character DOS compatible root directory filenames are allowed. Format is F.E where F may be between 1 and 8 characters
// and E may be between 1 and 3 characters, null terminated, non-case sensitive. The '*' and '?' wildcard characters may be used.
//
//access_mode
// "r" Open a file for reading. The file must exist.
// "r+" Open a file for reading and writing. The file must exist.
// "w" Create an empty file for writing. If a file with the same name already exists its content is erased.
// "w+" Create an empty file for writing and reading. If a file with the same name already exists its content is erased before it is opened.
// "a" Append to a file. Writing operations append data at the end of the file. The file is created if it doesn't exist.
// "a+" Open a file for reading and appending. All writing operations are done at the end of the file protecting the previous
// content from being overwritten. You can reposition (fseek) the pointer to anywhere in the file for reading, but
// writing operations will move back to the end of file. The file is created if it doesn't exist.
//
//Return value.
// If the file has been successfully opened the function will return a pointer to the file. Otherwise a null pointer is returned (0x00).
FFS_FILE* ffs_fopen (const char *filename, const char *access_mode)
{
BYTE file_number;
BYTE attribute_byte;
BYTE count;
BYTE read_file_name[8];
BYTE read_file_extension[3];
//----------------------------------------------
//----- LOOK FOR AN AVAILABLE FILE HANDLER -----
//----------------------------------------------
for (file_number = 0; file_number < FFS_FOPEN_MAX; file_number++)
{
if (ffs_file[file_number].flags.bits.file_is_open == 0)
{
//THIS HANDLER IS AVAILABLE
break;
}
if (file_number == (FFS_FOPEN_MAX - 1))
{
//LAST HANDLER TRIED - THE MAXIMUM NUMBER OF FILES ARE ALREADY OPEN
return(0);
}
}
//----- AVAILABLE FILE HANDLER FOUND BUT NOT YET ASSIGNED -----
//(file_number = the available handler)
//----------------------------------------------
//----- LOOK TO SEE IF FILE ALREADY EXISTS -----
//----------------------------------------------
ffs_file[file_number].current_cluster = ffs_find_file (filename, &ffs_file[file_number].file_size, &attribute_byte, &ffs_file[file_number].directory_entry_sector, &ffs_file[file_number].directory_entry_within_sector, &read_file_name[0], &read_file_extension[0]);
//--------------------------------------------------------
//----- IF FILE EXISTS ENSURE IT IS NOT ALREADY OPEN -----
//--------------------------------------------------------
if (ffs_file[file_number].current_cluster != 0xffffffff) //0xffffffff = file not found
{
for (count = 0; count < FFS_FOPEN_MAX; count++)
{
if (ffs_file[count].flags.bits.file_is_open)
{
if (
(count != file_number) &&
(ffs_file[count].directory_entry_sector == ffs_file[file_number].directory_entry_sector) &&
(ffs_file[count].directory_entry_within_sector == ffs_file[file_number].directory_entry_within_sector)
)
{
return(0);
}
}
}
}
//-------------------------------------------------------------
//----- IF OPENING A FILE FOR READ THEN CHECK FILE EXISTS -----
//-------------------------------------------------------------
if (ffs_file[file_number].current_cluster == 0xffffffff) //0xffffffff = file not found
{
if (*access_mode == 'r')
{
//ERROR - CAN'T OPEN FILE FOR READ AS IT DOESN'T EXIST
return(0);
}
}
//-----------------------------------------------------------------
//----- IF WRITING A FILE AND IT ALREADY EXISTS THEN ERASE IT -----
//-----------------------------------------------------------------
if (ffs_file[file_number].current_cluster != 0xffffffff) //0xffffffff = file not found
{
if (*access_mode == 'w')
{
//ERASE FILE
ffs_remove(filename);
ffs_file[file_number].current_cluster = 0xffffffff;
}
else
{
//FILE EXISTS AND IS NOT BEEING DELETED FIRST - MODIFY THE LAST ACCESSED TIME AND DATE IF USING A RTC
#ifdef USE_REAL_TIME_CLOCK
ffs_overwrite_last_directory_entry (&read_file_name[0], &read_file_extension[0], &attribute_byte, &ffs_file[file_number].file_size, &ffs_file[file_number].current_cluster, 0x02);
#endif
}
}
//----------------------------------------------------------------------
//----- IF WRITING OR APPENDING A FILE THEN CREATE IT IF NECESSARY -----
//----------------------------------------------------------------------
if (ffs_file[file_number].current_cluster == 0xffffffff)
{
if (ffs_create_new_file(filename, &ffs_file[file_number].current_cluster, &ffs_file[file_number].directory_entry_sector,
&ffs_file[file_number].directory_entry_within_sector) == 0) //This function checks for any wildcard characters in the filename and aborts if there are any
{
//ERROR - CAN'T CREATE A NEW FILE
return(0);
}
ffs_file[file_number].file_size = 0;
}
//------------------------------------------------------------
//----- FLAG THAT FILE IS OPEN AND SETUP FOR FILE ACCESS -----
//------------------------------------------------------------
ffs_file[file_number].flags.bits.file_is_open = 1;
ffs_file[file_number].flags.bits.access_error = 0;
ffs_file[file_number].flags.bits.end_of_file = 0;
ffs_file[file_number].flags.bits.file_size_has_changed = 0;
//--------------------------------------------------
//----- SET THE ACCESS MODE FLAGS FOR THE FILE -----
//--------------------------------------------------
if (*access_mode == 'r')
{
if (
(*(access_mode + 1) == '+') ||
((*(access_mode + 1) != 0x00) && (*(access_mode + 2) == '+'))
)
{
//----- ACCESS MODE IS 'R+' -----
ffs_file[file_number].flags.bits.read_permitted = 1;
ffs_file[file_number].flags.bits.write_permitted = 1;
ffs_file[file_number].flags.bits.write_append_only = 0;
}
else
{
//----- ACCESS MODE IS 'R' -----
ffs_file[file_number].flags.bits.read_permitted = 1;
ffs_file[file_number].flags.bits.write_permitted = 0;
ffs_file[file_number].flags.bits.write_append_only = 0;
}
//Set the current location to the beginning of the file
ffs_file[file_number].current_sector = 0;
ffs_file[file_number].current_byte = 0;
ffs_file[file_number].current_byte_within_file = 0;
ffs_file[file_number].flags.bits.inc_posn_before_next_rw = 0; //No increment before next read or write as we're already pointing to the next byte to access
}
else if (*access_mode == 'w')
{
if (
(*(access_mode + 1) == '+') ||
((*(access_mode + 1) != 0x00) && (*(access_mode + 2) == '+'))
)
{
//----- ACCESS MODE IS 'W+' -----
ffs_file[file_number].flags.bits.read_permitted = 1;
ffs_file[file_number].flags.bits.write_permitted = 1;
ffs_file[file_number].flags.bits.write_append_only = 0;
}
else
{
//----- ACCESS MODE IS 'W' -----
ffs_file[file_number].flags.bits.read_permitted = 0;
ffs_file[file_number].flags.bits.write_permitted = 1;
ffs_file[file_number].flags.bits.write_append_only = 0;
}
//Set the current location to the beginning of the file
ffs_file[file_number].current_sector = 0;
ffs_file[file_number].current_byte = 0;
ffs_file[file_number].current_byte_within_file = 0;
ffs_file[file_number].flags.bits.inc_posn_before_next_rw = 0; //No increment before next read or write as we're already pointing to the next byte to access
}
else if (*access_mode == 'a')
{
if (
(*(access_mode + 1) == '+') ||
((*(access_mode + 1) != 0x00) && (*(access_mode + 2) == '+'))
)
{
//----- ACCESS MODE IS 'A+' -----
ffs_file[file_number].flags.bits.read_permitted = 1;
ffs_file[file_number].flags.bits.write_permitted = 1;
ffs_file[file_number].flags.bits.write_append_only = 1;
}
else
{
//----- ACCESS MODE IS 'A' -----
ffs_file[file_number].flags.bits.read_permitted = 0;
ffs_file[file_number].flags.bits.write_permitted = 1;
ffs_file[file_number].flags.bits.write_append_only = 1;
}
//Set the current location to the last byte of the file
ffs_file[file_number].current_sector = 0; //These need setting to file start before calling ffs_fseek
ffs_file[file_number].current_byte = 0;
ffs_file[file_number].current_byte_within_file = 0;
ffs_file[file_number].flags.bits.inc_posn_before_next_rw = 0;
ffs_fseek(&ffs_file[file_number], 0, FFS_SEEK_END); //Use the fseek function to do this
if (ffs_file[file_number].file_size)
{
ffs_file[file_number].flags.bits.inc_posn_before_next_rw = 1; //Increment before doing the next read or write as we're pointing to the last byte of the file and the next byte will be a new byte
}
}
return(&ffs_file[file_number]);
}
//************************************************
//************************************************
//********** MOVE THE FILE BYTE POINTER **********
//************************************************
//************************************************
//This function is quite complex as it looks to see if the new location is in the same cluster as the current location to avoid having
//to read all of the FAT table entries for the file from the file start where possible. This results in a large speed improvement.
//
//origin
// The initial position from where the offset is applied
// FFS_SEEK_SET (0) Beginning of file
// FFS_SEEK_CUR (1) Current position of the file pointer
// FFS_SEEK_END (2) End of file
//offset
// Signed offset from the position set by origin
//returns
// 0 if successful, 1 otherwise
int ffs_fseek (FFS_FILE *file_pointer, long offset, int origin)
{
DWORD dw_temp;
DWORD bytes_to_new_posn;
DWORD bytes_per_cluster;
BYTE calculate_new_posn;
bytes_per_cluster = sectors_per_cluster * ffs_bytes_per_sector;
//-----------------------------------
//----- ENSURE THE FILE IS OPEN -----
//-----------------------------------
if (file_pointer->flags.bits.file_is_open == 0)
return(1);
if (origin == FFS_SEEK_SET)
{
//---------------------------------------
//----- ORIGIN IS BEGINNING OF FILE -----
//---------------------------------------
if (offset < 0)
{
//----- NEGATIVE VALUE - ILLEGAL -----
return(1);
}
else if (offset == 0)
{
//----- ZERO VALUE - SET TO START OF FILE -----
bytes_to_new_posn = 0;
}
else
{
//----- POSITIVE VALUE -----
bytes_to_new_posn = (DWORD)offset; //Set bytes from start value ready to move to requried location
}
}
else if (origin == FFS_SEEK_CUR)
{
//----------------------------------------------
//----- ORIGIN IS CURRENT POSITION IN FILE -----
//----------------------------------------------
bytes_to_new_posn = file_pointer->current_byte_within_file;
if (file_pointer->flags.bits.inc_posn_before_next_rw)
bytes_to_new_posn++;
if (offset < 0)
{
//OFFSET IS NEGATIVE
bytes_to_new_posn -= (DWORD)(0 - offset);
}
else
{
//OFFSET IS POSITIVE
bytes_to_new_posn += (DWORD)offset;
}
}
else if (origin == FFS_SEEK_END)
{
//---------------------------------
//----- ORIGIN IS END OF FILE -----
//---------------------------------
if (offset > 1)
{
//----- POSITIVE VALUE > 1 ILLEGAL -----
return(1);
}
else if (offset == 1)
{
bytes_to_new_posn = file_pointer->file_size;
}
else
{
bytes_to_new_posn = (file_pointer->file_size) - (DWORD)(0 - offset) - 1; //Set bytes from start value ready to move to requried location
}
}
else
{
//----- INVALID ORIGIN VALUE -----
return(1);
}
//------------------------------------------------
//----- ORIGIN IS NOW FROM BEGINNING OF FILE -----
//------------------------------------------------
//----- CHECK OFFSET IS VALID -----
if (bytes_to_new_posn > (file_pointer->file_size))
{
//NEW POSITION IS > FILE SIZE + 1 = ERROR
return(1);
}
else if (bytes_to_new_posn == (file_pointer->file_size))
{
//NEW POSITION = FILE SIZE SO IS THE POSITION READY FOR WRITING A NEW BYTE (DOESN'T ACTUALLY EXIST IN FILE YET)
if (bytes_to_new_posn)
{
bytes_to_new_posn--;
file_pointer->flags.bits.inc_posn_before_next_rw = 1;
}
else
{
file_pointer->flags.bits.inc_posn_before_next_rw = 0;
}
}
else
{
//NEW POSITION IS WITHIN FILE
file_pointer->flags.bits.inc_posn_before_next_rw = 0;
}
if (bytes_to_new_posn == 0)
{
//-------------------------------------------------
//----- OFFSET IS ZERO - SET TO START OF FILE -----
//-------------------------------------------------
file_pointer->current_cluster = get_file_start_cluster(file_pointer);
file_pointer->current_sector = 0;
file_pointer->current_byte = 0;
file_pointer->current_byte_within_file = 0;
}
else
{
//----- NON-ZERO VALUE -----
//--------------------------------------------------------------------------------------------------------------------------------------------
//----- IF NEW LOCATION IS WITHIN CURRENT CLUSTER THEN DO ADJUSTMENT AVOIDING HAVING TO READ EVERY FAT CLUSTER ENTRY FROM THE FILE START -----
//--------------------------------------------------------------------------------------------------------------------------------------------
if (bytes_to_new_posn == file_pointer->current_byte_within_file)
{
//----- NEW POSITION IS SAME AS EXISTING POSITION -----
calculate_new_posn = 0;
}
else if (bytes_to_new_posn < file_pointer->current_byte_within_file)
{
//----- NEW POSITION IS BEFORE CURRENT POSITION -----
if (
(file_pointer->current_byte_within_file - bytes_to_new_posn) <
(file_pointer->current_byte + (file_pointer->current_sector * ffs_bytes_per_sector))
)
{
//IN SAME CLUSTER
calculate_new_posn = 0;
//file_pointer->current_cluster = file_pointer->current_cluster; //Stays the same
dw_temp = bytes_to_new_posn;
bytes_to_new_posn = (file_pointer->current_byte_within_file - bytes_to_new_posn);
file_pointer->current_byte_within_file = dw_temp;
while (bytes_to_new_posn >= ffs_bytes_per_sector)
{
bytes_to_new_posn -= ffs_bytes_per_sector;
if (file_pointer->current_sector)
file_pointer->current_sector--;
else
calculate_new_posn = 1; //Error!
}
file_pointer->current_byte -= (WORD)bytes_to_new_posn;
if (file_pointer->current_byte >= ffs_bytes_per_sector) //Check for overflow into previous sector
{
file_pointer->current_byte += ffs_bytes_per_sector; //(Yes the '+' is correct!)
if (file_pointer->current_sector)
file_pointer->current_sector--;
else
calculate_new_posn = 1; //Error!
}
}
else
{
//IN DIFFERENT CLUSTER
calculate_new_posn = 1;
}
}
else
{
//----- NEW POSITION IS AFTER CURRENT POSITION -----
if (
(bytes_to_new_posn - file_pointer->current_byte_within_file) <
(bytes_per_cluster - (file_pointer->current_byte + (file_pointer->current_sector * ffs_bytes_per_sector)))
)
{
//IN SAME CLUSTER
calculate_new_posn = 0;
//file_pointer->current_cluster = file_pointer->current_cluster; //Stays the same
dw_temp = bytes_to_new_posn;
bytes_to_new_posn = (bytes_to_new_posn - file_pointer->current_byte_within_file);
file_pointer->current_byte_within_file = dw_temp;
while (bytes_to_new_posn >= ffs_bytes_per_sector)
{
bytes_to_new_posn -= ffs_bytes_per_sector;
if (file_pointer->current_sector < sectors_per_cluster)
file_pointer->current_sector++;
else
calculate_new_posn = 1; //Error!
}
file_pointer->current_byte += (WORD)bytes_to_new_posn;
if (file_pointer->current_byte >= ffs_bytes_per_sector)
{
file_pointer->current_byte -= ffs_bytes_per_sector;
if (file_pointer->current_sector < sectors_per_cluster)
file_pointer->current_sector++;
else
calculate_new_posn = 1; //Error!
}
}
else
{
//IN DIFFERENT CLUSTER
calculate_new_posn = 1;
}
}
if (calculate_new_posn)
{
//-------------------------------------------------------------------------------------------
//----- NEW LOCATION IS NOT IN THE CURRENT CLUSTER - FIND IT FROM THE START OF THE FILE -----
//-------------------------------------------------------------------------------------------
file_pointer->current_cluster = get_file_start_cluster(file_pointer);
file_pointer->current_sector = 0;
file_pointer->current_byte_within_file = bytes_to_new_posn;
//KEEP MOVING TO NEXT CLUSTER UNTIL WE'RE IN THE REQURIED CLUSTER
while (bytes_to_new_posn >= bytes_per_cluster)
{
bytes_to_new_posn -= bytes_per_cluster;
file_pointer->current_cluster = ffs_get_next_cluster_no(file_pointer->current_cluster);
}
//KEEP MOVING TO NEXT SECTOR UNTIL WE'RE IN THE REQURIED SECTOR (OF THE ALREADY FOUND CLUSTER)
while (bytes_to_new_posn >= ffs_bytes_per_sector)
{
bytes_to_new_posn -= ffs_bytes_per_sector;
file_pointer->current_sector++;
}
//STORE THE CURRENT BYTE NUMBER
file_pointer->current_byte = (WORD)bytes_to_new_posn;
}
}
file_pointer->flags.bits.end_of_file = 0; //The EOF flag is cleared when this function sucessfully is called
return(0);
}
//************************************************
//************************************************
//********** MOVE THE FILE BYTE POINTER **********
//************************************************
//************************************************
//(The value returned by ffs_getpos intended to be file system specific and to be used with this function. However as the position type is recomended
//to be a long we just use the ffs_ftell function as a long doesn't give us enough space to store everything we need for the low level position)
//Returns
// 0 if successful, 1 otherwise
int ffs_fsetpos (FFS_FILE *file_pointer, long *position)
{
//----- EXIT IF THIS FILE ISN'T ACTUALLY OPEN -----
if (file_pointer->flags.bits.file_is_open == 0)
return(1);
file_pointer->flags.bits.end_of_file = 0; //Clear the end of file flag
return(ffs_fseek(file_pointer, *position, FFS_SEEK_SET));
}
//******************************************************
//******************************************************
//********** GET THE CURRENT POSITION IN FILE **********
//******************************************************
//******************************************************
//Get the current file position.
long ffs_ftell (FFS_FILE *file_pointer)
{
//----- EXIT IF THIS FILE ISN'T ACTUALLY OPEN -----
if (file_pointer->flags.bits.file_is_open == 0)
return(1);
//----- RETURN THE CURRENT POSITION -----
if (file_pointer->flags.bits.inc_posn_before_next_rw)
return((long)file_pointer->current_byte_within_file + 1);
else
return((long)file_pointer->current_byte_within_file);
}
//******************************************************
//******************************************************
//********** GET THE CURRENT POSITION IN FILE **********
//******************************************************
//******************************************************
//(The value returned is intended to be file system specific and only to be used with fsetpos. However as the position type is recomended
//to be a long we just use the ffs_ftell function as a long doesn't give us enough space to store everything we need for the low level position)
//Returns
// 0 if successful, 1 otherwise
int ffs_fgetpos (FFS_FILE *file_pointer, long *position)
{
//----- EXIT IF THIS FILE ISN'T ACTUALLY OPEN -----
if (file_pointer->flags.bits.file_is_open == 0)
return(1);
//----- RETURN THE CURRENT POSITION -----
*position = ffs_ftell(file_pointer);
return(0);
}
//***********************************************************************
//***********************************************************************
//********** SET POSITION TO BEGINNING OF FILE AND CLEAR FLAGS **********
//***********************************************************************
//***********************************************************************
void ffs_rewind (FFS_FILE *file_pointer)
{
ffs_fseek (file_pointer, 0, FFS_SEEK_SET);
file_pointer->flags.bits.access_error = 0;
}
//****************************************
//****************************************
//********** WRITE BYTE TO FILE **********
//****************************************
//****************************************
//Data is converted to a byte before writing (int type is specified by ANSI-C)
//If there are no errors the written character is returned. If an error occurs, EOF is returned.
//#define ffs_putc(data, file_pointer) ffs_fputc(data, file_pointer) //Defined in header file - these 2 functions are equivalent
int ffs_fputc (int data, FFS_FILE *file_pointer)
{
DWORD dw_temp;
BYTE *buffer_pointer;
//Exit of card is write protected
if (ffs_card_write_protected)
return(FFS_EOF);
//-------------------------------------------------
//----- EXIT IF THIS FILE ISN'T ACTUALLY OPEN -----
//-------------------------------------------------
if (file_pointer->flags.bits.file_is_open == 0)
return(FFS_EOF);
//---------------------------------------------------------------------------------------------------------------------------
//----- CHECK THAT WRITING IN THIS POSITION IS PERMITTED FOR THE FOPEN MODE THAT WAS SPECIFIED WHEN THE FILE WAS OPENED -----
//---------------------------------------------------------------------------------------------------------------------------
if (file_pointer->flags.bits.write_permitted == 0)
{
//----- WRITING IS NOT PERMITTED -----
file_pointer->flags.bits.access_error = 1;
return(FFS_EOF);
}
if (file_pointer->flags.bits.write_append_only)
{
//----- APPEND MODE - WRITING MAY ONLY OCCUR AS NEW BYTES AT THE END OF THE FILE -----
dw_temp = file_pointer->current_byte_within_file;
if (file_pointer->flags.bits.inc_posn_before_next_rw)
{
dw_temp++;
}
if (dw_temp < file_pointer->file_size)
{
//CURRENTLY POINTING TO WITHIN FILE - SET TO END OF FILE
ffs_fseek(file_pointer, 1, FFS_SEEK_END);
}
}
//-----------------------------------------------------------------------
//----- CHECK FOR NEED TO MOVE TO NEXT BYTE POSITION BEFORE WRITING -----
//-----------------------------------------------------------------------
if (file_pointer->flags.bits.inc_posn_before_next_rw)
{
//----- INCREMENT BYTE COUNT -----
file_pointer->current_byte_within_file++;
file_pointer->current_byte++;
if (file_pointer->current_byte >= ffs_bytes_per_sector)
{
//----- MOVE TO NEXT SECTOR -----
file_pointer->current_byte = 0;
file_pointer->current_sector++;
if (file_pointer->current_sector >= sectors_per_cluster)
{
//----- MOVE TO NEXT CLUSTER -----
file_pointer->current_sector = 0;
if (file_pointer->current_byte_within_file >= file_pointer->file_size)
{
//ADD NEW CLUSTER TO END OF FILE
dw_temp = ffs_get_next_free_cluster();
if (dw_temp == 0xffffffff) //0xffffffff = no empty cluster found
{
//NOT ENOUGH SPACE FOR ANY MORE OF FILE
FFS_CE(1);
file_pointer->flags.bits.end_of_file = 1;
return(FFS_EOF);
}
//UPDATE THE CURRENT CLUSTER TO LINK TO THE NEXT CLUSTER
ffs_modify_cluster_entry_in_fat (file_pointer->current_cluster, dw_temp);
//UPDATE THE NEXT CLUSTER WITH THE END OF FILE MARKER
ffs_modify_cluster_entry_in_fat (dw_temp, 0x0fffffff);
}
else
{
//MOVE TO NEXT EXISTING CLUSTER
dw_temp = ffs_get_next_cluster_no(file_pointer->current_cluster);
if (dw_temp == 0xffffffff) //0xffffffff = no empty cluster found
{
//ERROR
FFS_CE(1);
file_pointer->flags.bits.access_error = 1;
return(FFS_EOF);
}
}
file_pointer->current_cluster = dw_temp;
}
}
file_pointer->flags.bits.inc_posn_before_next_rw = 0;
}
//-------------------------------------------------------------
//----- CHECK FOR NEED TO LOAD CURRENT SECTOR INTO BUFFER -----
//-------------------------------------------------------------
dw_temp = (
((file_pointer->current_cluster - 2) * sectors_per_cluster) +
(DWORD)file_pointer->current_sector +
data_area_start_sector
);
if (ffs_buffer_contains_lba != dw_temp)
{
ffs_read_sector_to_buffer(dw_temp);
}
//--------------------------
//----- WRITE THE BYTE -----
//--------------------------
buffer_pointer = &FFS_DRIVER_GEN_512_BYTE_BUFFER[0] + file_pointer->current_byte;
*buffer_pointer = (BYTE)(data & 0x00ff);
//---------------------------------------------------------------------------
//----- ADJUST FILE SIZE IF WE HAVE JUST WRITTEN TO THE END OF THE FILE -----
//---------------------------------------------------------------------------
if (file_pointer->current_byte_within_file >= file_pointer->file_size)
{
file_pointer->file_size++;
file_pointer->flags.bits.file_size_has_changed = 1;
}
//------------------------------------------------------------------------
//----- FLAG THAT WE NEED TO MOVE ON 1 BYTE NEXT TIME ACCESS IS MADE -----
//------------------------------------------------------------------------
//(we do this instead of incrementing now in case we have just done the last byte of the file)
file_pointer->flags.bits.inc_posn_before_next_rw = 1;
//----------------------------------------------------------
//----- FLAG THAT THE BUFFER NEEDS WRITING TO THE CARD -----
//----------------------------------------------------------
ffs_buffer_needs_writing_to_card = 1;
//-----------------------------------------------
//----- EXIT WITH THE BYTE THAT WAS WRITTEN -----
//-----------------------------------------------
return(data);
}
//**********************************************
//**********************************************
//********** READ NEXT BYTE FROM FILE **********
//**********************************************
//**********************************************
//The byte read is returned as an int value (int type is specified by ANSI-C)
//If the End Of File has been reached or there has been an error reading, the function returns EOF.
//#define ffs_getc(file_pointer) ffs_fgetc(file_pointer) //Defined in header file - these 2 functions are equivalent
int ffs_fgetc (FFS_FILE *file_pointer)
{
BYTE data;
DWORD dw_temp;
BYTE *buffer_pointer;
//-------------------------------------------------
//----- EXIT IF THIS FILE ISN'T ACTUALLY OPEN -----
//-------------------------------------------------
if (file_pointer->flags.bits.file_is_open == 0)
return(FFS_EOF);
//---------------------------------------------------------------------------------------------------------------------------
//----- CHECK THAT READING IN THIS POSITION IS PERMITTED FOR THE FOPEN MODE THAT WAS SPECIFIED WHEN THE FILE WAS OPENED -----
//---------------------------------------------------------------------------------------------------------------------------
if (file_pointer->flags.bits.read_permitted == 0)
{
//READ IS NOT PERMITTED
file_pointer->flags.bits.access_error = 1;
return(FFS_EOF);
}
//---------------------------------
//----- CHECK FOR END OF FILE -----
//---------------------------------
dw_temp = file_pointer->current_byte_within_file;
if (file_pointer->flags.bits.inc_posn_before_next_rw)
dw_temp++;
if (dw_temp >= file_pointer->file_size)
{
//TRYING TO READ PAST END OF FILE
file_pointer->flags.bits.end_of_file = 1;
return(FFS_EOF);
}
//-----------------------------------------------------------------------
//----- CHECK FOR NEED TO MOVE TO NEXT BYTE POSITION BEFORE READING -----
//-----------------------------------------------------------------------
if (file_pointer->flags.bits.inc_posn_before_next_rw)
{
//----- INCREMENT BYTE COUNT -----
file_pointer->current_byte_within_file++;
file_pointer->current_byte++;
if (file_pointer->current_byte >= ffs_bytes_per_sector)
{
//----- MOVE TO NEXT SECTOR -----
file_pointer->current_byte = 0;
file_pointer->current_sector++;
if (file_pointer->current_sector >= sectors_per_cluster)
{
//----- MOVE TO NEXT CLUSTER -----
file_pointer->current_sector = 0;
//Get the next cluster number
dw_temp = ffs_get_next_cluster_no(file_pointer->current_cluster);
if (disk_is_fat_32)
{
//FAT32
if (dw_temp >= 0x0ffffff8)
{
//There is no next cluster - all of file has been read
FFS_CE(1);
file_pointer->flags.bits.end_of_file = 1;
return(FFS_EOF);
}
}
else
{
//FAT16
if (dw_temp >= 0xfff8)
{
//There is no next cluster - all of file has been read
FFS_CE(1);
file_pointer->flags.bits.end_of_file = 1;
return(FFS_EOF);
}
}
file_pointer->current_cluster = dw_temp;
}
}
file_pointer->flags.bits.inc_posn_before_next_rw = 0;
}
//-------------------------------------------------------------
//----- CHECK FOR NEED TO LOAD CURRENT SECTOR INTO BUFFER -----
//-------------------------------------------------------------
dw_temp = (
((file_pointer->current_cluster - 2) * sectors_per_cluster) +
(DWORD)file_pointer->current_sector +
data_area_start_sector
);
if (ffs_buffer_contains_lba != dw_temp)
{
ffs_read_sector_to_buffer(dw_temp);
}
//------------------------
//----- GET THE BYTE -----
//------------------------
buffer_pointer = &FFS_DRIVER_GEN_512_BYTE_BUFFER[0] + file_pointer->current_byte;
data = (int)*buffer_pointer;
//------------------------------------------------------------------------
//----- FLAG THAT WE NEED TO MOVE ON 1 BYTE NEXT TIME ACCESS IS MADE -----
//------------------------------------------------------------------------
//(we do this instead of incrementing now in case we have just doen the last byte of the file)
file_pointer->flags.bits.inc_posn_before_next_rw = 1;
//--------------------------------------------
//----- EXIT WITH THE BYTE THAT WAS READ -----
//--------------------------------------------
return((int)data);
}
//******************************************
//******************************************
//********** WRITE STRING TO FILE **********
//******************************************
//******************************************
//Writes string to file until the null termination is reached. The null termination is not written to the
//file. If a new line character (\n) is required it should be included at the end of the string
//
//Returns
// Non-negative value if successful
// EOF if errored
int ffs_fputs (const char *string, FFS_FILE *file_pointer)
{
char *string_pointer;
int return_value;
//Exit of card is write protected
if (ffs_card_write_protected)
return(FFS_EOF);
//----- WRITE THE STRING -----
string_pointer = (char*)string;
while (*string_pointer != 0x00)
{
return_value = ffs_fputc ((int)*string_pointer++, file_pointer);
if (return_value == FFS_EOF)
return(FFS_EOF);
}
return(0);
}
//THIS IS A NON ANSI VARIENT OF THIS FUNCTION FOR USE WHEN WRITING A STRING FROM RAM WITH COMPILERS THAT WON'T
//DEAL WITH CONVERTING THE RAM STRING TO A CONSTANT STRING.
int ffs_fputs_char (char *string, FFS_FILE *file_pointer)
{
char *string_pointer;
int return_value;
//Exit of card is write protected
if (ffs_card_write_protected)