1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright 2023 Red Hat
4 */
5
6 #ifndef UDS_HASH_UTILS_H
7 #define UDS_HASH_UTILS_H
8
9 #include "numeric.h"
10
11 #include "geometry.h"
12 #include "indexer.h"
13
14 /* Utilities for extracting portions of a request name for various uses. */
15
16 /* How various portions of a record name are apportioned. */
17 enum {
18 VOLUME_INDEX_BYTES_OFFSET = 0,
19 VOLUME_INDEX_BYTES_COUNT = 8,
20 CHAPTER_INDEX_BYTES_OFFSET = 8,
21 CHAPTER_INDEX_BYTES_COUNT = 6,
22 SAMPLE_BYTES_OFFSET = 14,
23 SAMPLE_BYTES_COUNT = 2,
24 };
25
uds_extract_chapter_index_bytes(const struct uds_record_name * name)26 static inline u64 uds_extract_chapter_index_bytes(const struct uds_record_name *name)
27 {
28 const u8 *chapter_bits = &name->name[CHAPTER_INDEX_BYTES_OFFSET];
29 u64 bytes = (u64) get_unaligned_be16(chapter_bits) << 32;
30
31 bytes |= get_unaligned_be32(chapter_bits + 2);
32 return bytes;
33 }
34
uds_extract_volume_index_bytes(const struct uds_record_name * name)35 static inline u64 uds_extract_volume_index_bytes(const struct uds_record_name *name)
36 {
37 return get_unaligned_be64(&name->name[VOLUME_INDEX_BYTES_OFFSET]);
38 }
39
uds_extract_sampling_bytes(const struct uds_record_name * name)40 static inline u32 uds_extract_sampling_bytes(const struct uds_record_name *name)
41 {
42 return get_unaligned_be16(&name->name[SAMPLE_BYTES_OFFSET]);
43 }
44
45 /* Compute the chapter delta list for a given name. */
uds_hash_to_chapter_delta_list(const struct uds_record_name * name,const struct index_geometry * geometry)46 static inline u32 uds_hash_to_chapter_delta_list(const struct uds_record_name *name,
47 const struct index_geometry *geometry)
48 {
49 return ((uds_extract_chapter_index_bytes(name) >> geometry->chapter_address_bits) &
50 ((1 << geometry->chapter_delta_list_bits) - 1));
51 }
52
53 /* Compute the chapter delta address for a given name. */
uds_hash_to_chapter_delta_address(const struct uds_record_name * name,const struct index_geometry * geometry)54 static inline u32 uds_hash_to_chapter_delta_address(const struct uds_record_name *name,
55 const struct index_geometry *geometry)
56 {
57 return uds_extract_chapter_index_bytes(name) & ((1 << geometry->chapter_address_bits) - 1);
58 }
59
uds_name_to_hash_slot(const struct uds_record_name * name,unsigned int slot_count)60 static inline unsigned int uds_name_to_hash_slot(const struct uds_record_name *name,
61 unsigned int slot_count)
62 {
63 return (unsigned int) (uds_extract_chapter_index_bytes(name) % slot_count);
64 }
65
66 #endif /* UDS_HASH_UTILS_H */
67