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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2023 Red Hat
*/
#ifndef UDS_HASH_UTILS_H
#define UDS_HASH_UTILS_H
#include "numeric.h"
#include "geometry.h"
#include "indexer.h"
/* Utilities for extracting portions of a request name for various uses. */
/* How various portions of a record name are apportioned. */
enum {
VOLUME_INDEX_BYTES_OFFSET = 0,
VOLUME_INDEX_BYTES_COUNT = 8,
CHAPTER_INDEX_BYTES_OFFSET = 8,
CHAPTER_INDEX_BYTES_COUNT = 6,
SAMPLE_BYTES_OFFSET = 14,
SAMPLE_BYTES_COUNT = 2,
};
static inline u64 uds_extract_chapter_index_bytes(const struct uds_record_name *name)
{
const u8 *chapter_bits = &name->name[CHAPTER_INDEX_BYTES_OFFSET];
u64 bytes = (u64) get_unaligned_be16(chapter_bits) << 32;
bytes |= get_unaligned_be32(chapter_bits + 2);
return bytes;
}
static inline u64 uds_extract_volume_index_bytes(const struct uds_record_name *name)
{
return get_unaligned_be64(&name->name[VOLUME_INDEX_BYTES_OFFSET]);
}
static inline u32 uds_extract_sampling_bytes(const struct uds_record_name *name)
{
return get_unaligned_be16(&name->name[SAMPLE_BYTES_OFFSET]);
}
/* Compute the chapter delta list for a given name. */
static inline u32 uds_hash_to_chapter_delta_list(const struct uds_record_name *name,
const struct index_geometry *geometry)
{
return ((uds_extract_chapter_index_bytes(name) >> geometry->chapter_address_bits) &
((1 << geometry->chapter_delta_list_bits) - 1));
}
/* Compute the chapter delta address for a given name. */
static inline u32 uds_hash_to_chapter_delta_address(const struct uds_record_name *name,
const struct index_geometry *geometry)
{
return uds_extract_chapter_index_bytes(name) & ((1 << geometry->chapter_address_bits) - 1);
}
static inline unsigned int uds_name_to_hash_slot(const struct uds_record_name *name,
unsigned int slot_count)
{
return (unsigned int) (uds_extract_chapter_index_bytes(name) % slot_count);
}
#endif /* UDS_HASH_UTILS_H */
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