// Display (Crystalfontz CFA-635 USB LCD)
//
// Douglas Thrift
//
// $Id$

#include <iostream>

#include <fcntl.h>
#include <termios.h>

#include "Display.hpp"

static uint16_t GetCRC(uint8_t *buffer, size_t length)
{
	static const uint16_t table[256] = {
		0x00000,0x01189,0x02312,0x0329B,0x04624,0x057AD,0x06536,0x074BF,
		0x08C48,0x09DC1,0x0AF5A,0x0BED3,0x0CA6C,0x0DBE5,0x0E97E,0x0F8F7,
		0x01081,0x00108,0x03393,0x0221A,0x056A5,0x0472C,0x075B7,0x0643E,
		0x09CC9,0x08D40,0x0BFDB,0x0AE52,0x0DAED,0x0CB64,0x0F9FF,0x0E876,
		0x02102,0x0308B,0x00210,0x01399,0x06726,0x076AF,0x04434,0x055BD,
		0x0AD4A,0x0BCC3,0x08E58,0x09FD1,0x0EB6E,0x0FAE7,0x0C87C,0x0D9F5,
		0x03183,0x0200A,0x01291,0x00318,0x077A7,0x0662E,0x054B5,0x0453C,
		0x0BDCB,0x0AC42,0x09ED9,0x08F50,0x0FBEF,0x0EA66,0x0D8FD,0x0C974,
		0x04204,0x0538D,0x06116,0x0709F,0x00420,0x015A9,0x02732,0x036BB,
		0x0CE4C,0x0DFC5,0x0ED5E,0x0FCD7,0x08868,0x099E1,0x0AB7A,0x0BAF3,
		0x05285,0x0430C,0x07197,0x0601E,0x014A1,0x00528,0x037B3,0x0263A,
		0x0DECD,0x0CF44,0x0FDDF,0x0EC56,0x098E9,0x08960,0x0BBFB,0x0AA72,
		0x06306,0x0728F,0x04014,0x0519D,0x02522,0x034AB,0x00630,0x017B9,
		0x0EF4E,0x0FEC7,0x0CC5C,0x0DDD5,0x0A96A,0x0B8E3,0x08A78,0x09BF1,
		0x07387,0x0620E,0x05095,0x0411C,0x035A3,0x0242A,0x016B1,0x00738,
		0x0FFCF,0x0EE46,0x0DCDD,0x0CD54,0x0B9EB,0x0A862,0x09AF9,0x08B70,
		0x08408,0x09581,0x0A71A,0x0B693,0x0C22C,0x0D3A5,0x0E13E,0x0F0B7,
		0x00840,0x019C9,0x02B52,0x03ADB,0x04E64,0x05FED,0x06D76,0x07CFF,
		0x09489,0x08500,0x0B79B,0x0A612,0x0D2AD,0x0C324,0x0F1BF,0x0E036,
		0x018C1,0x00948,0x03BD3,0x02A5A,0x05EE5,0x04F6C,0x07DF7,0x06C7E,
		0x0A50A,0x0B483,0x08618,0x09791,0x0E32E,0x0F2A7,0x0C03C,0x0D1B5,
		0x02942,0x038CB,0x00A50,0x01BD9,0x06F66,0x07EEF,0x04C74,0x05DFD,
		0x0B58B,0x0A402,0x09699,0x08710,0x0F3AF,0x0E226,0x0D0BD,0x0C134,
		0x039C3,0x0284A,0x01AD1,0x00B58,0x07FE7,0x06E6E,0x05CF5,0x04D7C,
		0x0C60C,0x0D785,0x0E51E,0x0F497,0x08028,0x091A1,0x0A33A,0x0B2B3,
		0x04A44,0x05BCD,0x06956,0x078DF,0x00C60,0x01DE9,0x02F72,0x03EFB,
		0x0D68D,0x0C704,0x0F59F,0x0E416,0x090A9,0x08120,0x0B3BB,0x0A232,
		0x05AC5,0x04B4C,0x079D7,0x0685E,0x01CE1,0x00D68,0x03FF3,0x02E7A,
		0x0E70E,0x0F687,0x0C41C,0x0D595,0x0A12A,0x0B0A3,0x08238,0x093B1,
		0x06B46,0x07ACF,0x04854,0x059DD,0x02D62,0x03CEB,0x00E70,0x01FF9,
		0x0F78F,0x0E606,0x0D49D,0x0C514,0x0B1AB,0x0A022,0x092B9,0x08330,
		0x07BC7,0x06A4E,0x058D5,0x0495C,0x03DE3,0x02C6A,0x01EF1,0x00F78,
	};
	register uint16_t crc(0xffff);

	while (length--)
		crc = (crc >> 8) ^ table[(crc ^ *buffer++) & 0xff];

	return ~crc;
}

Display::Packet::Packet(Display::Packet::Command command, const std::string &data) : command(command), length(data.size())
{
	if (length > sizeof (this->data))
		throw;

	::memcpy(this->data, data.data(), length);

	crc = GetCRC(reinterpret_cast<uint8_t *>(this), length + 2);
}

void operator<<(int fd, const Display::Packet::Packet &packet)
{
	if (packet.length != sizeof (packet.data))
		::memcpy(const_cast<uint8_t *>(packet.data) + packet.length, &packet.crc, 2);

	Posix::Write(fd, &packet, packet.length + 4);
}

void operator>>(int fd, Display::Packet::Packet &packet)
{
	Posix::Read(fd, &packet, 2);
	Posix::Read(fd, packet.data, packet.length);
	Posix::Read(fd, &packet.crc, 2);

	std::printf("0x%02x\n%i\n", packet.command, packet.length);

	std::cout << '[' << std::string((char*)(packet.data), size_t(packet.length)) << ']' << std::endl;
}

Display::Display(const std::string &device) : ucom(Posix::Open(device, O_RDWR | O_NOCTTY))
{
	::termios state;

	Posix::CheckError(::tcgetattr(ucom, &state));
	Posix::CheckError(::cfsetospeed(&state, B115200));
	Posix::CheckError(::cfsetispeed(&state, B115200));

	state.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | INPCK | ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXOFF);
	state.c_iflag |= IGNPAR;
	state.c_oflag &= ~(OPOST | ONLCR | ONOCR | ONLRET);
	state.c_cflag &= ~(CSIZE | PARENB | PARODD | HUPCL | CRTSCTS);
	state.c_cflag |= CREAD | CS8 | CSTOPB | CLOCAL;
	state.c_lflag &= ~(ISIG | ICANON | IEXTEN | ECHO);
	state.c_lflag |= NOFLSH;

	Posix::CheckError(::tcsetattr(ucom, TCSANOW, &state));
}

bool Display::Ping(const std::string &data)
{
	Packet packet(Packet::PingCommand, data), response;

	ucom << packet;

	do
	{
		ucom >> response;
	}
	while (packet.command | Packet::Response != response.command);

	return true;
}