Compression on/off compile option.

Modem/config.h

@@ -19,7 +19,7 @@
 #define CONFIG_AFSK_RXTIMEOUT 0				// How long a read operation from the modem
 											// will wait for data before timing out.
 
-#define CONFIG_AFSK_PREAMBLE_LEN 350UL		// The length of the packet preamble in milliseconds
+#define CONFIG_AFSK_PREAMBLE_LEN 150UL		// The length of the packet preamble in milliseconds
 #define CONFIG_AFSK_TRAILER_LEN 50UL		// The length of the packet tail in milliseconds
 
 #endif

Modem/protocol/mp1.c

@@ -20,11 +20,15 @@ static uint8_t lastByte = 0x00;
 
 // We also need a buffer for compressing and
 // decompressing packet data.
-static uint8_t compressionBuffer[MP1_MAX_FRAME_LENGTH+10];
+#if MP1_ENABLE_COMPRESSION
+	static uint8_t compressionBuffer[MP1_MAX_DATA_SIZE];
+#endif
 
+#if SERIAL_DEBUG
 // An int to hold amount of free RAM updated
 // by the FREE_RAM function;
 static int FREE_RAM;
+#endif
 
 // The GET_BIT macro is used in the interleaver
 // and deinterleaver to access single bits of a
@@ -84,14 +88,16 @@ static void mp1Decode(MP1 *mp1) {
 	packet.dataLength = mp1->packetLength - 2 - (header & MP1_HEADER_PADDED)*padding;
 
 	// Check if we have received a compressed packet
-	if (header & MP1_HEADER_COMPRESSION) {
+	if (MP1_ENABLE_COMPRESSION && (header & MP1_HEADER_COMPRESSION)) {
 		// If we have, we decompress it and use the
 		// decompressed data for the packet
+		#if MP1_ENABLE_COMPRESSION
 			if (SERIAL_DEBUG) kprintf("[CS=%d] ", packet.dataLength);
 			size_t decompressedSize = decompress(buffer, packet.dataLength);
 			if (SERIAL_DEBUG) kprintf("[DS=%d]", decompressedSize);
 			packet.dataLength = decompressedSize;
 			memcpy(mp1->buffer, compressionBuffer, decompressedSize);
+		#endif
 	} else {
 		// If the packet was not compressed, we shift
 		// the data in our buffer back down to the actual
@@ -420,6 +426,7 @@ void mp1Send(MP1 *mp1, void *_buffer, size_t length) {
 
 	// We then try to compress the data to see
 	// if we can save some space with compression.
+	#if MP1_ENABLE_COMPRESSION
 		size_t compressedSize = compress(buffer, length);
 		if (compressedSize != 0 && compressedSize < length) {
 			// Compression saved us some space, we'll
@@ -436,6 +443,7 @@ void mp1Send(MP1 *mp1, void *_buffer, size_t length) {
 			// We are not going to use compression,
 			// so we don't do anything.
 		}
+	#endif
 
 	// Transmit the HDLC_FLAG to signify start of TX
 	kfile_putc(HDLC_FLAG, mp1->modem);
@@ -568,15 +576,18 @@ bool mp1CarrierSense(MP1 *mp1) {
 
 // A handy debug function that can determine
 // how much available memory we have left.
+#if SERIAL_DEBUG
 int freeRam(void) {
    extern int __heap_start, *__brkval; 
    int v;
    FREE_RAM = (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval);
    return FREE_RAM; 
 }
+#endif
 
 // This function compresses data using
 // the Heatshrink library
+#if MP1_ENABLE_COMPRESSION
 size_t compress(uint8_t *input, size_t length) {
 	heatshrink_encoder *hse = heatshrink_encoder_alloc(8, 4);
 	if (hse == NULL) {
@@ -601,9 +612,11 @@ size_t compress(uint8_t *input, size_t length) {
 	heatshrink_encoder_free(hse);
 	return written;
 }
+#endif
 
 // This function decompresses data using
 // the Heatshrink library
+#if MP1_ENABLE_COMPRESSION
 size_t decompress(uint8_t *input, size_t length) {
 	heatshrink_decoder *hsd = heatshrink_decoder_alloc(MP1_MAX_FRAME_LENGTH, 8, 4);
 	if (hsd == NULL) {
@@ -628,6 +641,7 @@ size_t decompress(uint8_t *input, size_t length) {
 	heatshrink_decoder_free(hsd);
 	return written;
 }
+#endif
 
 
 // Following is the functions responsible

Modem/protocol/mp1.h

@@ -4,9 +4,17 @@
 #include <cfg/compiler.h>
 #include <io/kfile.h>
 
+// Options
+#define MP1_ENABLE_COMPRESSION false
+#define MP1_ENABLE_CSMA true
+
 // Frame sizing & checksum
 #define MP1_INTERLEAVE_SIZE 12
-#define MP1_MAX_FRAME_LENGTH 22 * MP1_INTERLEAVE_SIZE
+#if MP1_ENABLE_COMPRESSION
+	#define MP1_MAX_FRAME_LENGTH 22 * MP1_INTERLEAVE_SIZE
+#else
+	#define MP1_MAX_FRAME_LENGTH 56 * MP1_INTERLEAVE_SIZE
+#endif
 #define MP1_HEADER_SIZE 1
 #define MP1_CHECKSUM_SIZE 1
 #define MP1_MAX_DATA_SIZE MP1_MAX_FRAME_LENGTH - MP1_HEADER_SIZE - MP1_CHECKSUM_SIZE
@@ -16,7 +24,6 @@
 
 // These two parameters are used for 
 // P-persistent CSMA
-#define MP1_ENABLE_CSMA false
 #define MP1_SETTLE_TIME 100UL		// The minimum wait time before considering sending
 #define MP1_P_PERSISTENCE 85UL		// The probability (between 0 and 255) for sending
 #define MP1_TXDELAY 150UL			// Delay between turning on the transmitter and sending

buildrev.h

@@ -1,2 +1,2 @@
-#define VERS_BUILD 1576
+#define VERS_BUILD 1598
 #define VERS_HOST  "shard"