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///////////////////////////////////////////////////////////////////////////////
//  protocol.h - Home automation library
//
//  Copyright (C) 2009 Jochen Toppe <jochen@jtoee.com>. All right reserved.
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//
//  This library 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.  See the GNU
//  Lesser General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public
//  License along with this library; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
///////////////////////////////////////////////////////////////////////////////
#ifndef PROTOCOL_H
#define PROTOCOL_H

#include "common.h"

//
// Package data definitions.
//
//! initializes a packet
#define INIT_BYTE 	0x00
//! starts a packet
#define START_BYTE 	0xAA
//! max payload
#define MAX_PACKET_SIZE 0x4

//!
//! protocol peculiarities
//!
#define NUMBER_OF_INIT_BYTES 0x5

//!
//! receiver modes
//!
#define  garbage_mode 	0x1
#define  pre_header 	0x2
#define  pkg_header 	0x3
#define  pkg_data 	0x4

// Package structure
// +-------------------------+--------------------------------------------------+-------+
// | Pre Header              | Header                                           | Data  |
// +------------+------------+--------+------------+---------------+------------+-------+
// | PHDR       | SBT        | ADR    | CMD        | INF           | CHK        | DT    |
// +------------+------------+--------+------------+---------------+------------+-------+
// | pre-header | start byte | source | command &  | DT Len, ACK,  | checksum   | dat a |
// |            |            | target | request id | checksum      |            | (0-4) |
// +------------+------------+--------+------------+---------------+------------+-------+

// bit structure of the ADR field
// +------------------+--------------+
// | [source device]  | [target id ] |
// +------------------+--------------+
// | [7 6 5 4]        | [3 2 1 0]    |
// +------------------+--------------+
#define getADRSource(adr) (adr >> 4)
#define getADRTarget(adr) (adr & 0xF)
#define generateADR(src, tar) ((src << 4)|(tar & 0xF))

// bit structure of the INF field and convenience macros
// the reserved field is for future bi-directional acknowledgement
// of command receipt.
//
// The checksum are the upper 5 bits of the total checksum which is
// composed of the CHK field (lower 8 bits) and these 5 bits.
//
// The reserved bit is for the future auto-acknowledge feature which will let a 
// remote device equipped with both transmitter and receiver acknowledge the
// receipt of a command
// +----------------+-------+---------------+
// | [data length ] | [res] | [checksum]    |
// +----------------+-------+---------------+
// | [7 6]          | [5]   | [4 3 2 1 0]   |
// +----------------+-------+---------------+
#define getINFDataLength(inf) (inf >> 6)
#define getINFReservedBit(inf)  ((inf>> 5) & 0x1)
#define getINFChecksum(inf) (inf & 0x1F)
//#define generateINF(len,ack,chk) (len << 7)|((res&0x1)<<6)|(chk&0x1F00)

// bit structure of the CMD field and convenience macros
// +------------------+----------------+
// | [command]        | [request id ]  |
// +------------------+----------------+
// | [7 6 5 4]        | [3 2 1 0]      |
// +------------------+----------------+
#define getCMD(cmd) (cmd >> 4)
#define getRID(cmd) (cmd & 0xF)
#define generateCMD(cmd, rid) ((cmd << 4)|(rid & 0xF))


#define COMMAND_TYPE_REMOTE 'R'
#define COMMAND_TYPE_LOCAL  'L'
#define COMMAND_TYPE_NOOP   'N'

// command structure definition
struct Command {
    // optional command type
    uint8_t commandType;
    // source device id (set to FF in case the parity could not be computed)
    uint8_t sourceDevice;
    //  command
    uint8_t command;
    // request id
    uint8_t requestId;
    // target device (i.e. the receiving / executing device)
    uint8_t targetDevice;
    // checksum
    uint16_t checksum;
    // data size
    uint8_t dataSize;
    // data
    uint8_t data[MAX_PACKET_SIZE];
    // raw src field
    uint8_t  _adr;
    // raw command and request id
    uint8_t  _cmd;
    // taw inf - target address, data length, and ack required bit
    uint8_t  _inf;
    // raw chksum
};

//
extern struct Command _incomingCommand;
extern struct Command _outgoingCommand;

//
// Process an incoming byte. Returns 0 if this yielded nothing, returns 1 if a ready
// and valid command object can be retrieved via the currentCommand variable.
//
uint8_t parse_incoming(uint8_t incoming);

//
// Assemble a command into the outgoingCommand structure. The current device id is also autmatically emdedded into the command object.
//
void assemble_command(uint8_t command, uint8_t requestId, uint8_t targetAddress, uint8_t dataSize, uint8_t data[]);

//
// send the outgoing command structure
//
void send_command(void);

//
// Returns one if the parity checks out ok.
//
uint8_t check_src_parity(struct Command *aCommand);

//
// function pointers to hook into functionality
//
// can be used to turn on/off the transmission circuits.
//

extern void (*_proto_pre_send_hook)(void);
extern void (*_proto_post_send_hook)(void);

// set the pre send hook
#define setPreSendHook(fx) _proto_pre_send_hook=fx
// set the post send hook
#define setPostSendHook(fx) _proto_post_send_hook=fx

// request id generator, a revolving unsigned int
extern uint8_t _request_id;
#define next_request_id() _request_id++

#endif