Revision 0:032752cac4de, committed 2011-12-09

Comitter:

mbed2f

Date:

Fri Dec 09 21:06:12 2011 +0000

Commit message:

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Dec 09 21:06:12 2011 +0000
@@ -0,0 +1,69 @@
+#include <mbed.h>
+
+// Boolean types
+#define TRUE 1
+#define FALSE 0
+
+
+int main(void)
+{
+    unsigned char        ReadSample = 0xFF;
+    // Indices to track where the playback and recording should take place in the
+    // audio buffer.  The recording can occur one sample behind the current playback
+    // index since it is no longer required.
+    int                  Index = 0;
+    // Reverse the direction the buffer is walked between each iteration to save memory
+    int                  Direction = 1;
+    // Have audio to playback
+    int                  Playback = FALSE;
+    // The amount of data to be recorded before starting reverse playback
+    // NOTE: Probably want this to be configured at runtime via a knob, etc.
+    int                  ChunkSize = 256;
+    // Allocate a buffer to be used for the audio recording
+    // NOTE: Just showing a 20k buffer in a static for this example
+    static const size_t  BufferSize = 20 * 1024;
+    static unsigned char Buffer[BufferSize];
+    
+    // Infinite loop of recording and reverse playback
+    for (;;)
+    {
+        unsigned char PlaySample;
+
+        // Read out the sample from the buffer to be played back
+        if (Playback)
+        {
+            PlaySample = Buffer[Index];
+            // NOTE: Just printing out samples in reverse
+            printf("%d: %d\r\n", Index, PlaySample);
+            wait(0.2f);
+        }
+        
+        // Obtain current audio sample from the A/D converter.
+        // NOTE: I am just faking these values in this sample with an incrementing value
+        ReadSample++;
+        
+        // Record the sample into the buffer right where a space was freed up from the PlaySample read above
+        Buffer[Index] = ReadSample;
+        
+        // Increment the buffer pointer
+        Index += Direction;
+        
+        // Check to see if the chunk has been filled
+        if (Index < 0)
+        {
+            // Now have a chunk to be played back
+            Playback = TRUE;
+            // Reverse the direction of playback and recording
+            Direction *= -1;
+            Index = 0;
+        }
+        else if (Index >= ChunkSize)
+        {
+            // Now have a chunk to be played back
+            Playback = TRUE;
+            // Reverse the direction of playback and recording
+            Direction *= -1;
+            Index = ChunkSize - 1;
+        }
+    }
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Fri Dec 09 21:06:12 2011 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/078e4b97a13e