/*
 * Copyright (c) 2010 Luc Verhaegen <libv@skynet.be>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/*
 * Based on get-edid.c by John Fremlin, but this one is actual C code, and
 * the content of get-edid.c or this file is not exactly rocket-science.
 */

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/io.h>
#include <unistd.h>
#include <fcntl.h>

#include <libx86.h>

static int
vbe_call(struct LRMI_regs *regs, unsigned char al, unsigned char bl)
{
	regs->eax = 0x4F00 | al;
	regs->ebx = bl;

	if (!LRMI_int(0x10, regs)) {
		fprintf(stderr, "%s: LRMI_int failed!\n", __func__);
		return -1;
	}

	if (regs->eax == 0x4F)
		return 0;
	else if (regs->eax == 0x014F) {
		fprintf(stderr, "VBE Call 0x%02X failed!\n", al);
		return -1;
	} else {
		fprintf(stderr, "VBE Call 0x%02X is unsupported!\n", al);
		return -1;
	}
}

static int
vbe_controller_info(void)
{
	struct LRMI_regs regs = { 0 };
	unsigned char *info;
	int ret;

	info = LRMI_alloc_real(512);
	if (!info) {
		fprintf(stderr, "Error: %s: LRMI_alloc_real failed!\n",
			__func__);
		return -1;
	}

	memcpy(info, "VBE2", 4);
	regs.es = ((unsigned long) info) >> 4;
	regs.edi = 0;

	ret = vbe_call(&regs, 0x00, 0x00);
	if (!ret)
		printf("Found VBE Version %d.%d.\n", info[5], info[4]);

	LRMI_free_real(info);

	return ret;
}

static int
edid_dump(unsigned char *edid, int size)
{
	char name[4], filename[14];
	unsigned short model;
	int fd;

	if ((size < 128) ||
	    memcmp(edid, "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", 8)) {
		fprintf(stderr, "Error: Invalid EDID header!\n");
		return -1;
	}

	name[0] = edid[8] >> 2;
	name[1] = ((edid[8] & 0x03) << 3) | (edid[9] >> 5);
	name[2] = edid[9] & 0x1F;

	if ((name[0] && (name[0] < 27)) &&
	    (name[1] && (name[1] < 27)) &&
	    (name[2] && (name[2] < 27))) {
		name[0] += 0x60;
		name[1] += 0x60;
		name[2] += 0x60;
	} else {
		name[0] = 'x';
		name[1] = 'x';
		name[2] = 'x';
	}
	name[3] = 0;

	model = edid[0x0A] | (edid[0x0B] << 8);

	sprintf(filename, "%s-%04x.edid", name, model);

	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL);
	if (fd < 0) {
		fprintf(stderr, "Failed to open %s: %s\n",
			filename, strerror(errno));
		return -errno;
	}

	if (write(fd, edid, size) == -1) {
		fprintf(stderr, "Failed to write to %s: %s\n",
			filename, strerror(errno));
		return -errno;
	}

	printf("Dumped %d bytes to %s\n", size, filename);

	close(fd);

	return 0;
}

static int
vbe_edid_read(void)
{
	struct LRMI_regs regs = { 0 };
	unsigned char *edid;
	int ret = 0;

	edid = LRMI_alloc_real(128);
	if (!edid) {
		fprintf(stderr, "Error: %s: LRMI_ALLOC_REAL failed!\n",
			__func__);
		return -1;
	}

	regs.es = ((unsigned long) edid) >> 4;
	regs.edi = 0;
	regs.ecx = 0;
	regs.edx = 1;

	ret = vbe_call(&regs, 0x15, 0x01);
	if (!ret)
		edid_dump(edid, 128);

	LRMI_free_real(edid);

	return ret;
}

int
main(int argc, char *argv[])
{
	int ret;

	if (iopl(3)) {
		fprintf(stderr, "Error: iopl failed: %s\n", strerror(errno));
		return -errno;
	}

	if (!LRMI_init()) {
		fprintf(stderr, "Error: LRMI_init() failed!\n");
		return -1;
	}

	ret = vbe_controller_info();
	if (!ret)
		ret = vbe_edid_read();

	return ret;
}