/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup genarch_drivers
 * @{
 */
/**
 * @file
 * @brief EGA driver.
 */

#include <genarch/drivers/ega/ega.h>
#include <putchar.h>
#include <mm/page.h>
#include <mm/as.h>
#include <mm/slab.h>
#include <arch/mm/page.h>
#include <synch/spinlock.h>
#include <arch/types.h>
#include <arch/asm.h>
#include <memstr.h>
#include <console/chardev.h>
#include <console/console.h>
#include <sysinfo/sysinfo.h>
#include <ddi/ddi.h>

/*
 * The EGA driver.
 * Simple and short. Function for displaying characters and "scrolling".
 */

SPINLOCK_INITIALIZE(egalock);
static uint32_t ega_cursor;
static uint8_t *videoram;
static uint8_t *backbuf;
static ioport8_t *ega_base;

#define SPACE  0x20
#define STYLE  0x07

#define EMPTY_CHAR  (STYLE << 8 | SPACE)

/*
 * This function takes care of scrolling.
 */
static void ega_check_cursor(void)
{
	if (ega_cursor < EGA_SCREEN)
		return;
	
	memmove((void *) videoram, (void *) (videoram + EGA_COLS * 2),
	    (EGA_SCREEN - EGA_COLS) * 2);
	memmove((void *) backbuf, (void *) (backbuf + EGA_COLS * 2),
	    (EGA_SCREEN - EGA_COLS) * 2);
	memsetw(videoram + (EGA_SCREEN - EGA_COLS) * 2, EGA_COLS, EMPTY_CHAR);
	memsetw(backbuf + (EGA_SCREEN - EGA_COLS) * 2, EGA_COLS, EMPTY_CHAR);
	ega_cursor = ega_cursor - EGA_COLS;
}

static void ega_show_cursor(void)
{
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0a);
	uint8_t stat = pio_read_8(ega_base + EGA_DATA_REG);
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0a);
	pio_write_8(ega_base + EGA_DATA_REG, stat & (~(1 << 5)));
}

static void ega_move_cursor(void)
{
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0e);
	pio_write_8(ega_base + EGA_DATA_REG, (uint8_t) ((ega_cursor >> 8) & 0xff));
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0f);
	pio_write_8(ega_base + EGA_DATA_REG, (uint8_t) (ega_cursor & 0xff));
}

static void ega_sync_cursor(void)
{
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0e);
	uint8_t hi = pio_read_8(ega_base + EGA_DATA_REG);
	pio_write_8(ega_base + EGA_INDEX_REG, 0x0f);
	uint8_t lo = pio_read_8(ega_base + EGA_DATA_REG);
	
	ega_cursor = (hi << 8) | lo;
	
	if (ega_cursor >= EGA_SCREEN)
		ega_cursor = 0;
	
	if ((ega_cursor % EGA_COLS) != 0)
		ega_cursor = (ega_cursor + EGA_COLS) - ega_cursor % EGA_COLS;
	
	memsetw(videoram + ega_cursor * 2, EGA_SCREEN - ega_cursor, EMPTY_CHAR);
	memsetw(backbuf + ega_cursor * 2, EGA_SCREEN - ega_cursor, EMPTY_CHAR);
	
	ega_check_cursor();
	ega_move_cursor();
	ega_show_cursor();
}

static void ega_display_char(char ch, bool silent)
{
	backbuf[ega_cursor * 2] = ch;
	backbuf[ega_cursor * 2 + 1] = STYLE;
	
	if (!silent) {
		videoram[ega_cursor * 2] = ch;
		videoram[ega_cursor * 2 + 1] = STYLE;
	}
}

static void ega_putchar(outdev_t *dev __attribute__((unused)), const char ch, bool silent)
{
	ipl_t ipl;
	
	ipl = interrupts_disable();
	spinlock_lock(&egalock);
	
	switch (ch) {
	case '\n':
		ega_cursor = (ega_cursor + EGA_COLS) - ega_cursor % EGA_COLS;
		break;
	case '\t':
		ega_cursor = (ega_cursor + 8) - ega_cursor % 8;
		break; 
	case '\b':
		if (ega_cursor % EGA_COLS)
			ega_cursor--;
		break;
	default:
		ega_display_char(ch, silent);
		ega_cursor++;
		break;
	}
	ega_check_cursor();
	
	if (!silent)
		ega_move_cursor();
	
	spinlock_unlock(&egalock);
	interrupts_restore(ipl);
}

static outdev_t ega_console;
static outdev_operations_t ega_ops = {
	.write = ega_putchar
};

void ega_init(ioport8_t *base, uintptr_t videoram_phys)
{
	/* Initialize the software structure. */
	ega_base = base;
	
	backbuf = (uint8_t *) malloc(EGA_VRAM_SIZE, 0);
	if (!backbuf)
		panic("Unable to allocate backbuffer.");
	
	videoram = (uint8_t *) hw_map(videoram_phys, EGA_VRAM_SIZE);
	
	/* Synchronize the back buffer and cursor position. */
	memcpy(backbuf, videoram, EGA_VRAM_SIZE);
	ega_sync_cursor();
	
	outdev_initialize("ega", &ega_console, &ega_ops);
	stdout = &ega_console;
	
	sysinfo_set_item_val("fb", NULL, true);
	sysinfo_set_item_val("fb.kind", NULL, 2);
	sysinfo_set_item_val("fb.width", NULL, EGA_COLS);
	sysinfo_set_item_val("fb.height", NULL, EGA_ROWS);
	sysinfo_set_item_val("fb.blinking", NULL, true);
	sysinfo_set_item_val("fb.address.physical", NULL, videoram_phys);
}

void ega_redraw(void)
{
	memcpy(videoram, backbuf, EGA_VRAM_SIZE);
	ega_move_cursor();
	ega_show_cursor();
}

/** @}
 */