/* Sense/Net Bus Interface Library for Raspberry Pi.
 * Sensiplicity Systems
 * 
 *  Copyright 2015
 * 
 *  Department of Botany and Plant Pathology
 *  Center for Genome Research and Biocomputing
 *  Oregon State University
 *  Corvallis, OR 97331
 * 
 * This program is not free software; you can not redistribute it and/or
 * modify it at all.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. */
#ifndef SENSE_NET_H
#define SENSE_NET_H
#include <stdint.h>
#include <stdarg.h>

/* This library interfaces to the Sense/Net bus, a bus protocol
 * for connecting large numbers of environmental sensors. It's designed to
 * work with an RS-485 transceiver connected to a serial port, with the RS-485
 * DE/RE_n line connected to the DTR signal. When DTR is up, receive is enabled.
 * When DTR is down, transmit is enabled. */

/* Open the serial port on the raspberry pi bridge. 
 * Returns 0 on success, -1 on error. Errors messages are printed to stdout. */
int sn_init();

/* Node ID datatype. */
typedef uint8_t node_t[9];

/* Get sensor data from a node.
 * The structure of the data is defined by the node type.
 *    bus is the bus the node is located on.
 *    *node is the node to get data from.
 *    *data will be filled with the data from the node. It should be able to contain
 *          128 bytes.
 *    *size will be set to the number of bytes in data.
 * If an error occurs, *data is not set and *size is set to 0.
 * Returns 0 on success, -1 on bus error, -2 on node error. */
int sn_get_data(int bus, node_t node, char *data, int *size);

/* Send a packet to a node. If the node replies with a packet, it will
 * be placed into *reply_data.
 *   bus is the bus the node is located on.
 *   cmd is the header command number. Allowed range is 0-7.
 *   *node is the node to send the packet to.
 *   *data is the data to be sent.
 *   data_size is the size of the data to be sent (max. 128).
 *   *status will be set to the status code received from the packet, if any.
 *   *reply_data will be filled with data from the reply packet. It must
 *               be able to hold 128 bytes.
 *   *reply_size will be set to the size of the reply.
 * *status, *reply_data, and *reply size may be NULL. If *reply_size is NULL,
 * *reply_data will not be set. *data may be null if data_size is 0.
 * Returns 0 on success (no reply), 1 on success (reply), 
 * -1 on I/O error, -2 on corrupted reply */
int sn_send_packet(int bus, int cmd, node_t node, const char *data, int data_size, int *status, char *reply_data, int *reply_size);

/* Send a packet to a node. If the node replies with a packet, it will
 * be placed into *reply_data. If a reply is not received, the request will be re-tried up to
 * two more times.
 *   bus is the bus the node is located on.
 *   cmd is the header command number. Allowed range is 0-7.
 *   *node is the node to send the packet to.
 *   *data is the data to be sent.
 *   data_size is the size of the data to be sent (max. 128).
 *   *status will be set to the status code received from the packet, if any.
 *   *reply_data will be filled with data from the reply packet. It must
 *               be able to hold 128 bytes.
 *   *reply_size will be set to the size of the reply.
 * *status, *reply_data, and *reply size may be NULL. If *reply_size is NULL,
 * *reply_data will not be set. *data may be null if data_size is 0.
 * Returns 0 on success (no reply), 1 on success (reply), 
 * -1 on I/O error, -2 on corrupted reply */
int sn_send_packet_r(int bus, int cmd, node_t node, const char *data, int data_size, int *status, char *reply_data, int *reply_size);

/* Struct containing a node ID and type code. */
typedef struct node_enum_t {
	int bus; /* The bus the node is on. */
	node_t id; /* Node ID. */
	uint16_t type; /* Node typecode. */
} node_enum_t;

/* Discover the nodes on the bus.
 *   bus is the bus the node is located on.
 *   **nodes will be set to point to an array of node_enum_ts.
 *           Free() this array when you are done with it.
 *    *num_nodes will be set to the number of node IDs in the array. */
void sn_enumerate(int bus, node_enum_t **nodes, int *num_nodes);

/* Shutdown the library and close the serial port. */
void sn_shutdown(void);

/* Return a human-readable description of a node typecode. */
const char *sn_type_str(uint16_t typecode);

/* Calculate CRC of a Sense/Net packet. packet[0] is the header.
 * If this function is computed over a whole packet, including the
 * CRC at the end, a return value of 0 indicates a valid packet. */
uint16_t calc_crc(uint8_t *packet, int packet_length);

/* Extract a uint16_t from a little-endian data packet.
 * Index is the index of the first byte of the field in the packet data. */
uint16_t sn_uint16(uint8_t *packet_data, uint8_t index);

/* Extract a uint32_t from a little-endian data packet.
 * Index is the index of the first byte of the field in the packet data. */
uint32_t sn_uint32(uint8_t *packet_data, uint8_t index);

#endif