/* gpt.h -- the GPT reader, and a block device of one partition.
 * docs/v4.0.0/STICK.md 3 and 4; docs/v4.0.0/plans/2026-10-26-stick-2-gpt-reader.md.
 */
#ifndef STARKERNEL_GPT_H
#define STARKERNEL_GPT_H

#include <stdint.h>
#include <stddef.h>
#include "blkio.h"

/* The two StarshipOS partition types, as their GUIDs are on disk. */
extern const uint8_t gpt_type_starship_identity[16];   /* 23BEBFE1-4817-4CF3-A537-9069BF159788 */
extern const uint8_t gpt_type_starship_artemis[16];    /* BCD7B586-1C8E-4EEF-86A3-273A8D8EE624 */

typedef struct {
    uint8_t  type[16];
    uint64_t first_lba;
    uint64_t last_lba;
} gpt_part_t;

#define GPT_OK    0      /* a valid GPT */
#define GPT_NONE  1      /* not a GPT disk (or one whose sectors are not 512 bytes): read it raw */
#define GPT_BAD   2      /* a GPT, but its header or entry array does not check out: not used */

/* Read `disk`'s protective MBR, primary GPT header and partition-entry array,
 * checking both CRC-32s, the revision, the sizes and the geometry. On GPT_OK,
 * `*count` partitions with a non-zero type (at most `max`) are in `parts`.
 * Reads only. */
int gpt_read(blkio_dev_t *disk, gpt_part_t *parts, unsigned max, unsigned *count);

/* The index of the first partition of `type`, or -1. */
int gpt_find(const gpt_part_t *parts, unsigned count, const uint8_t type[16]);

/* A partition as a block device: its block n is the disk's block
 * first_fblock + n; blocks past fblocks are refused. */
typedef struct {
    blkio_dev_t *disk;
    uint32_t     first_fblock;
    uint32_t     fblocks;
} gpt_part_dev_t;

/* Open `dev` as partition `p` of `disk`, its state in `st` (which must live
 * as long as `dev`). BLKIO_EINVAL for a partition that does not start and end
 * on a 1 KiB block, or that runs past the disk. */
int gpt_part_open(blkio_dev_t *dev, gpt_part_dev_t *st, blkio_dev_t *disk, const gpt_part_t *p);

/* CRC-32 (IEEE 802.3, reflected, polynomial 0xEDB88320), as GPT uses. */
uint32_t gpt_crc32(const void *buf, size_t len);

#endif /* STARKERNEL_GPT_H */