Im working on making actual readLine functions. My end result is to add them to the SD library and make them core functions for everyone to use. Then again I could just make it another library and leave the SD library alone.
I'll come back when it is done and decided.
Ok, I have decided to make this its own extension library. However in the meantime, here is the sketch I have been working on.
The sketch is messy but the library won't be.
/*
Demonstrate functions to copy, scan, read and delete lines from a file
The circuit:
* SD card attached to SPI bus as follows:
** MOSI - pin 11
** MISO - pin 12
** CLK - pin 13
** CS - pin 4
created March 29 2016
by Andrew Mascolo
*/
#include <SPI.h>
#include <SD.h>
#define isSpace(x) (x == ' ')
#define isComma(x) (x == ',')
template<class T> inline Print &operator <<(Print &str, T arg)
{
str.print(arg);
return str;
}
struct LinesAndPositions
{
int NumberOfLines; // number of lines in file
int SOL[50]; // start of line in file
int EOL[50]; // end of line in file
};
template<typename T, size_t N>
char* ReadSelectedLinesFromFile(T (&buf)[N], char * filename, char * StrOfLines)
{
char tempBuf[N];
Serial << "Reading multiple lines, please wait";
for (unsigned short i = 0, j = strlen(StrOfLines), index = 0; i <= j; i++)
{
char C = (*StrOfLines++);
if (isComma(C) || (i == j))
{
ReadLineFromFile(tempBuf, filename, index);
strncat(buf, tempBuf, N);
index = 0;
}
else if (isSpace(C)) continue;
else
index = (index * 10) + C - '0';
if ((i % 2) == 0)
Serial << ".";
}
Serial.println();
return buf;
}
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(115200);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
Serial.print("Initializing SD card...");
// On the Ethernet Shield, CS is pin 4. It's set as an output by default.
// Note that even if it's not used as the CS pin, the hardware SS pin
// (10 on most Arduino boards, 53 on the Mega) must be left as an output
// or the SD library functions will not work.
pinMode(53, OUTPUT);
if (!SD.begin(53)) {
Serial.println("initialization failed!");
return;
}
Serial.println("initialization done.");
// Uncomment this if you already have a copy of COPY.txt
CopyFiles("test.txt", "COPY.txt");
ShowFileContents("test.txt");
// Uncomment this if you don't already have a copy of COPY.txt
//CopyFiles("COPY.txt", "test.txt");
//ShowFileContents("COPY.txt");
LinesAndPositions X = FindLinesAndPositions("test.txt");
Serial << "\nNumber of lines from test.txt:" << X.NumberOfLines << "\n";
Serial << "--------------------------------\n\n";
char buf[50] = {NULL};
//ReadLineFromFile(buf, "test.txt", 1) << "\n";
//ReadMultipleLinesFromFile(buf, "test.txt", 1, 2);
ReadSelectedLinesFromFile(buf, "test.txt", "1,3,4");
Serial << "From passed in buffer:\n" << buf << "\n";
Serial << "--------------------------------\n";
//DeleteLineFromFile("test.txt", 2); // delete line 2 from file
//DeleteMultipleLinesFromFile("test.txt", 2, 3); delete lines 2 through 3 from file
DeleteSelectedLinesFromFile("test.txt", "1, 3, 4"); // delete individual lines 1,3,4 from file. **Takes a few seconds**
Serial.println("Done.");
ShowFileContents("test.txt");
X = FindLinesAndPositions("test.txt");
Serial << "\nNumber of lines from test.txt:" << X.NumberOfLines << "\n";
}
void loop()
{
// nothing happens after setup
}
struct LinesAndPositions FindLinesAndPositions(char* filename)
{
File myFile;
LinesAndPositions LNP;
myFile = SD.open(filename);
if (myFile)
{
LNP.NumberOfLines = 0;
LNP.SOL[0] = 0; //the very first start-of-line index is always zero
unsigned int Pos;
while (myFile.available())
{
Pos = myFile.position(); // get the position. Put before .read(), otherwise it will not start at 0 like it should.
if (myFile.read() == '\n') // read until the newline character has been found
{
LNP.EOL[LNP.NumberOfLines] = Pos; // record the location of where it is in the file
LNP.NumberOfLines++; // update the number of lines found
LNP.SOL[LNP.NumberOfLines] = Pos + 1; // the start-of-line is always 1 character more than the end-of-line location
}
}
LNP.EOL[LNP.NumberOfLines] = Pos + 1; // record the last locations
LNP.NumberOfLines += 1; // record the last line
myFile.close();
}
return LNP;
}
void CopyFiles(char* ToFile, char* FromFile)
{
File myFileOrig;
File myFileTemp;
if (SD.exists(ToFile))
SD.remove(ToFile);
//Serial << "\nCopying Files. From:" << FromFile << " -> To:" << ToFile << "\n";
myFileTemp = SD.open(ToFile, FILE_WRITE);
myFileOrig = SD.open(FromFile);
if (myFileOrig)
{
while (myFileOrig.available())
{
myFileTemp.write( myFileOrig.read() ); // make a complete copy of the original file
}
myFileOrig.close();
myFileTemp.close();
//Serial.println("done.");
}
}
void ShowFileContents(char* filename)
{
Serial.println(filename);
File myFile = SD.open(filename);
if (myFile)
{
while (myFile.available()) {
Serial.write(myFile.read());
}
Serial.println();
myFile.close();
}
}
void DeleteLineFromFile(char * filename, int Line)
{
DeleteMultipleLinesFromFile(filename, Line, Line);
}
void DeleteSelectedLinesFromFile(char * filename, char * StrOfLines)
{
byte offset = 0;
Serial << "Deleting multiple lines, please wait";
for (unsigned short i = 0, j = strlen(StrOfLines), index = 0; i <= j; i++)
{
char C = (*StrOfLines++);
if (isComma(C) || (i == j))
{
DeleteLineFromFile(filename, index - offset);
offset++;
index = 0;
}
else if (isSpace(C)) continue;
else
index = (index * 10) + C - '0';
if ((i % 2) == 0)
Serial << ".";
}
Serial.println();
}
void DeleteMultipleLinesFromFile(char * filename, int SLine, int ELine)
{
File myFileOrig;
File myFileTemp;
// If by some chance it exists, remove the temp file from the card
if (SD.exists("tempFile.txt"))
SD.remove("tempFile.txt");
// Get the start and end of line positions from said file
LinesAndPositions FileLines = FindLinesAndPositions(filename);
if ((SLine > FileLines.NumberOfLines) || (ELine > FileLines.NumberOfLines))
return;
myFileTemp = SD.open("tempFile.txt", FILE_WRITE);
myFileOrig = SD.open(filename);
if (myFileOrig)
{
unsigned int position = 0;
char C;
while (myFileOrig.available())
{
position = myFileOrig.position();
C = myFileOrig.read();
// Copy the file but exclude the entered lines by user
if ((position < FileLines.SOL[SLine - 1]) || (position > FileLines.EOL[ELine - 1]))
myFileTemp.write(C);
}
myFileOrig.close();
myFileTemp.close();
}
//copy the contents of tempFile back to the original file
CopyFiles(filename, "tempFile.txt");
// Remove the tempfile from the SD card
if (SD.exists("tempFile.txt"))
SD.remove("tempFile.txt");
}
char* ReadLineFromFile(char* Buffer, char* filename, const byte Line)
{
return ReadMultipleLinesFromFile(Buffer, filename, Line, Line);
}
char* ReadMultipleLinesFromFile(char* Buffer, char* filename, byte SLine, byte ELine)
{
SLine -= 1;
ELine -= 1;
File myFile = SD.open(filename);
if (myFile)
{
LinesAndPositions FileLines = FindLinesAndPositions(filename);
// go to beginning of line
myFile.seek(FileLines.SOL[SLine]);
while (myFile.available())
{
unsigned int Pos = myFile.position();
if (Pos <= (FileLines.EOL[ELine]))
{
Buffer[Pos - FileLines.SOL[SLine]] = myFile.read();
Buffer[Pos - FileLines.SOL[SLine] + 1] = '\0';
}
else
break;
}
myFile.close();
return Buffer;
}
return 0;
}
TEST.TXT (24 Bytes)
COPY.TXT (63 Bytes)