#include <time.h>
#include <sys/time.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <lcd.h>

#ifdef DMALLOC
#include <dmalloc.h>
#endif

#define SPI_IOCTL 0x600

static int spidev;
static unsigned char lastdata[LCD_H][LCD_W] = {{0}};

inline void spi_command(unsigned char command) {
	ioctl(spidev, SPI_IOCTL, &command);
}

void cursorxy(int x, int y) {
	spi_command(0x40 | (y & 0x07));
	spi_command(0x80 | (x & 0x7f));
}

void clearram() {
	unsigned char buf[LCD_BYTES] = {0};
	cursorxy(0, 0);
	write(spidev, buf, LCD_BYTES);
}


/* Public functions */

int getticks() {
	struct timeval tv;
	struct timezone tz;
	gettimeofday(&tv, &tz);
	
	return tv.tv_sec * 1000 + tv.tv_usec / 1000;
}

void lcd_initialize() {
	spidev = open("/dev/spi", O_RDWR);
	
	spi_command(0x21); // Extended instruction set
	spi_command(0x80 | 70); // LCD contrast voltage
	spi_command(0x13); // LCD bias
	spi_command(0x20); // Normal instruction set
	spi_command(0x0C); // Display normal
	
	clearram();
}

void lcd_update(unsigned char buf[LCD_H][LCD_W]) {
	int i, firstline = -1, lastline = 0;
	
	for (i = 0; i < LCD_H; i++) {
		if (memcmp(buf[i], lastdata[i], LCD_W) != 0) {
			firstline = i;
			break;
		}
	}
	
	for (i = firstline; i < LCD_H; i++) {
		if (memcmp(buf[i], lastdata[i], LCD_W) != 0) {
			lastline = i + 1;
		}
	}
	
	if (firstline < 0) // No changes
		return;
	
	cursorxy(0, firstline);
	write(spidev, &buf[firstline][0], (lastline - firstline) * LCD_W);
	memcpy(&lastdata[0][0], &buf[0][0], LCD_BYTES);
}

void lcd_scroll(unsigned char lbuf[LCD_H][LCD_W], unsigned char rbuf[LCD_H][LCD_W], int direction) {
	// 1 = right, 0 = left
	const int border = 2;
	unsigned char screen[LCD_H][LCD_W];
	int pos, rpos, y;
	int ticks = getticks(), rticks;

	for (pos = 0; pos <= LCD_W + border; pos += 8) {
		if (direction)
			rpos = pos;
		else
			rpos = LCD_W + border - pos;
		
		for (y = 0; y < LCD_H; y++) {
			memcpy(&screen[y][0], &lbuf[y][rpos], LCD_W - rpos);
			
			if (rpos > 0 && rpos <= border) {
				memset(&screen[y][LCD_W - rpos], 0, rpos);
			} else if (rpos > border && rpos <= LCD_W) {
				memset(&screen[y][LCD_W - rpos], 0, border);
			}
			
			if (rpos > border)
				memcpy(&screen[y][LCD_W - rpos + border], &rbuf[y][0], rpos - border);
		}
		
		lcd_update(screen);
		
		ticks += 1000 / 50;
		rticks = ticks - getticks();
		if (rticks > 0)
			usleep(rticks * 1000);
	}
	
	if (direction)
		lcd_update(rbuf);
	else
		lcd_update(lbuf);
}