Trying to fix seek() / peek() interactions.

libraries/SD/File.cpp

@@ -15,14 +15,17 @@
 #include <SD.h>
 
 void File::write(uint8_t val) {
+  SD.c = -1;
   SD.file.write(val);
 }
 
 void File::write(const char *str) {
+  SD.c = -1;
   SD.file.write(str);
 }
 
 void File::write(const uint8_t *buf, size_t size) {
+  SD.c = -1;
   SD.file.write(buf, size);
 }
 
@@ -52,10 +55,12 @@ void File::flush() {
 }
 
 boolean File::seek(uint32_t pos) {
+  SD.c = -1;
   return SD.file.seekSet(pos);
 }
 
 uint32_t File::position() {
+  if (SD.c != -1) return SD.file.curPosition() - 1;
   return SD.file.curPosition();
 }
 

libraries/SD/examples/DumpFile/DumpFile.pde

@@ -0,0 +1,64 @@
+/*
+  SD card file dump
+ 
+ This example shows how to read a file from the SD card using the
+ SD library and send it over the serial port.
+ 	
+ The circuit:
+ * SD card attached to SPI bus as follows:
+ ** MOSI - pin 11
+ ** MISO - pin 12
+ ** CLK - pin 13
+ ** CS - pin 4
+ 
+ created  22 December 2010
+ 
+ This example code is in the public domain.
+ 	 
+ */
+
+#include <SD.h>
+
+// On the Ethernet Shield, CS is pin 4. Note that even if it's not
+// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
+// 53 on the Mega) must be left as an output or the SD library
+// functions will not work.
+const int chipSelect = 4;
+
+void setup()
+{
+  Serial.begin(9600);
+  Serial.print("Initializing SD card...");
+  // make sure that the default chip select pin is set to
+  // output, even if you don't use it:
+  pinMode(10, OUTPUT);
+  
+  // see if the card is present and can be initialized:
+  if (!SD.begin(chipSelect)) {
+    Serial.println("Card failed, or not present");
+    // don't do anything more:
+    return;
+  }
+  Serial.println("card initialized.");
+  
+  // open the file. note that only one file can be open at a time,
+  // so you have to close this one before opening another.
+  File dataFile = SD.open("datalog.txt");
+
+  // if the file is available, write to it:
+  if (dataFile) {
+    while (dataFile.available()) {
+      Serial.write(dataFile.read());
+    }
+    dataFile.close();
+  }  
+  // if the file isn't open, pop up an error:
+  else {
+    Serial.println("error opening datalog.txt");
+  } 
+}
+
+void loop()
+{
+}
+