/* amiga.c - Read amiga partition tables (RDB).  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2002,2004,2005,2006,2007  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *(at your option) any later version.
 *
 *  GRUB 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <grub/disk.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/partition.h>
#include <r_types.h>
R_PACKED(
	struct grub_amiga_rdsk {
		/* "RDSK".  */
		grub_uint8_t magic[4];
		grub_uint32_t size;
		grub_int32_t checksum;
		grub_uint32_t scsihost;
		grub_uint32_t blksz;
		grub_uint32_t flags;
		grub_uint32_t badblcklst;
		grub_uint32_t partitionlst;
		grub_uint32_t fslst;

		/* The other information is not important for us.  */
	});

R_PACKED(
	struct grub_amiga_partition {
		/* "PART".  */
		grub_uint8_t magic[4];
		grub_int32_t size;
		grub_int32_t checksum;
		grub_uint32_t scsihost;
		grub_uint32_t next;
		grub_uint32_t flags;
		grub_uint32_t unused1[2];
		grub_uint32_t devflags;
		grub_uint8_t namelen;
		grub_uint8_t name[31];
		grub_uint32_t unused2[15];

		grub_uint32_t unused3[3];
		grub_uint32_t heads;
		grub_uint32_t unused4;
		grub_uint32_t block_per_track;
		grub_uint32_t unused5[3];
		grub_uint32_t lowcyl;
		grub_uint32_t highcyl;

		grub_uint32_t firstcyl;
	});

struct grub_partition_map grub_amiga_partition_map;

static grub_err_t
amiga_partition_map_iterate(grub_disk_t disk,
	int (*hook) (grub_disk_t disk,
		const grub_partition_t partition,
		void *closure),
	void *closure) {
	struct grub_partition part;
	struct grub_amiga_rdsk rdsk;
	int partno = 0;
	int next = -1;
	unsigned pos;

	/* The RDSK block is one of the first 15 blocks.  */
	for (pos = 0; pos < 15; pos++) {
		/* Read the RDSK block which is a descriptor for the entire disk.  */
		if (grub_disk_read (disk, pos, 0, sizeof (rdsk), &rdsk)) {
			return grub_errno;
		}

		if (strcmp ((char *)rdsk.magic, "RDSK") == 0) {
			/* Found the first PART block.  */
			next = grub_be_to_cpu32 (rdsk.partitionlst);
			break;
		}
	}

	if (next == -1) {
		return grub_error (GRUB_ERR_BAD_PART_TABLE,
			"Amiga partition map not found");
	}

	/* The end of the partition list is marked using "-1".  */
	while (next != -1) {
		struct grub_amiga_partition apart;

		/* Read the RDSK block which is a descriptor for the entire disk.  */
		if (grub_disk_read (disk, next, 0, sizeof (apart), &apart)) {
			return grub_errno;
		}

		/* Calculate the first block and the size of the partition.  */
		part.start = (grub_be_to_cpu32 (apart.lowcyl) * grub_be_to_cpu32 (apart.heads) * grub_be_to_cpu32 (apart.block_per_track));
		part.len = ((grub_be_to_cpu32 (apart.highcyl) - grub_be_to_cpu32 (apart.lowcyl) + 1) * grub_be_to_cpu32 (apart.heads) * grub_be_to_cpu32 (apart.block_per_track));

		part.offset = (grub_off_t)next * 512;
		part.number = partno;
		part.index = 0;
		part.partmap = &grub_amiga_partition_map;

		if (hook (disk, &part, closure)) {
			return grub_errno;
		}

		next = grub_be_to_cpu32 (apart.next);
		partno++;
	}

	return 0;
}

/* Partition map type.  */
struct grub_partition_map grub_amiga_partition_map = {
	.name = "amiga",
	.iterate = amiga_partition_map_iterate,
};