92 lines
2.3 KiB
C++
92 lines
2.3 KiB
C++
// Demo of rewriting a line read by fgets
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#include <SdFat.h>
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// SD card chip select pin
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const uint8_t chipSelect = SS;
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// file system
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SdFat sd;
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// print stream
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ArduinoOutStream cout(Serial);
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//------------------------------------------------------------------------------
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// store error strings in flash memory
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#define error(s) sd.errorHalt_P(PSTR(s))
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//------------------------------------------------------------------------------
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void demoFgets() {
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char line[25];
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int c;
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uint32_t pos;
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// open test file
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SdFile rdfile("FGETS.TXT", O_RDWR);
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// check for open error
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if (!rdfile.isOpen()) error("demoFgets");
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// list file
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cout << pstr("-----Before Rewrite\r\n");
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while ((c = rdfile.read()) >= 0) Serial.write(c);
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rdfile.rewind();
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// read lines from the file to get position
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while (1) {
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pos = rdfile.curPosition();
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if (rdfile.fgets(line, sizeof(line)) < 0) {
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error("Line not found");
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}
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// find line that contains "Line C"
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if (strstr(line, "Line C"))break;
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}
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// rewrite line with 'C'
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if (!rdfile.seekSet(pos))error("seekSet");
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rdfile.println("Line R");
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rdfile.rewind();
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// list file
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cout << pstr("\r\n-----After Rewrite\r\n");
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while ((c = rdfile.read()) >= 0) Serial.write(c);
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// close so rewrite is not lost
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rdfile.close();
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}
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//------------------------------------------------------------------------------
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void makeTestFile() {
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// create or open test file
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SdFile wrfile("FGETS.TXT", O_WRITE | O_CREAT | O_TRUNC);
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// check for open error
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if (!wrfile.isOpen()) error("MakeTestFile");
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// write test file
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wrfile.write_P(PSTR(
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"Line A\r\n"
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"Line B\r\n"
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"Line C\r\n"
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"Line D\r\n"
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"Line E\r\n"
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));
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wrfile.close();
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}
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//------------------------------------------------------------------------------
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void setup(void) {
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Serial.begin(9600);
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while (!Serial){} // wait for Leonardo
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cout << pstr("Type any character to start\n");
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while (Serial.read() <= 0) {}
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delay(400); // catch Due reset problem
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// initialize the SD card at SPI_HALF_SPEED to avoid bus errors with
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// breadboards. use SPI_FULL_SPEED for better performance.
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if (!sd.begin(chipSelect, SPI_HALF_SPEED)) sd.initErrorHalt();
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makeTestFile();
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demoFgets();
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cout << pstr("\nDone\n");
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}
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void loop(void) {}
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