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Direct serial line in/out. P-persistent CSMA. SLIP compatibility.

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This commit is contained in:
Mark Qvist 2014-04-27 18:54:01 +02:00
parent 74542aa87a
commit bd11c5ee83
9 changed files with 180 additions and 52 deletions
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14
Modem/protocol/mp1.h
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@ -6,11 +6,20 @@
// Frame sizing & checksum
#define MP1_INTERLEAVE_SIZE 12
#define MP1_MAX_FRAME_LENGTH 22 * MP1_INTERLEAVE_SIZE
#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
#define MP1_MIN_FRAME_LENGTH MP1_INTERLEAVE_SIZE
#define MP1_DATA_BLOCK_SIZE ((MP1_INTERLEAVE_SIZE/3)*2)
#define MP1_MAX_FRAME_LENGTH 250
#define MP1_CHECKSUM_INIT 0xAA
// These two parameters are used for
// P-persistent CSMA
#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
// We need to know some basic HDLC flag bytes
#define HDLC_FLAG 0x7E
#define HDLC_RESET 0x7F
@ -44,10 +53,12 @@ typedef struct MP1 {
uint8_t checksum_out; // Rolling checksum for outgoing packets
bool reading; // True when we have seen a HDLC flag
bool escape; // We need to know if we are in an escape sequence
ticks_t settleTimer; // Timer used for carrier sense settling
long correctionsMade; // A counter for how many corrections were made to a packet
uint8_t interleaveCounter; // Keeps track of when we have received an entire interleaved block
uint8_t interleaveOut[MP1_INTERLEAVE_SIZE]; // A buffer for interleaving bytes before they are sent
uint8_t interleaveIn[MP1_INTERLEAVE_SIZE]; // A buffer for storing interleaved bytes before they are deinterleaved
uint8_t randomSeed; // A seed for the pseudo-random number generator
} MP1;
// A struct encapsulating a network packet
@ -61,6 +72,7 @@ void mp1Init(MP1 *mp1, KFile *modem, mp1_callback_t callback);
void mp1Read(MP1 *mp1, int byte);
void mp1Poll(MP1 *mp1);
void mp1Send(MP1 *mp1, void *_buffer, size_t length);
bool mp1CarrierSense(MP1 *mp1);
int freeRam(void);
size_t compress(uint8_t *input, size_t length);