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#ifndef DB_H
#define DB_H 1
#include <stdint.h>
struct Header {
char magic[8]; // "\0plocate";
uint32_t version; // 2 is the current version.
uint32_t hashtable_size;
uint32_t extra_ht_slots;
uint32_t num_docids;
uint64_t hash_table_offset_bytes;
uint64_t filename_index_offset_bytes;
// Version 1 and up only.
uint32_t max_version; // Nominally 1 or 2, but can be increased if more features are added in a backward-compatible way.
uint32_t zstd_dictionary_length_bytes;
uint64_t zstd_dictionary_offset_bytes;
// Only if max_version >= 2, and only relevant for updatedb.
uint64_t directory_data_length_bytes;
uint64_t directory_data_offset_bytes;
uint64_t next_zstd_dictionary_length_bytes;
uint64_t next_zstd_dictionary_offset_bytes;
uint64_t conf_block_length_bytes;
uint64_t conf_block_offset_bytes;
// Only if max_version >= 2.
bool check_visibility;
};
struct Trigram {
uint32_t trgm;
uint32_t num_docids;
uint64_t offset;
bool operator==(const Trigram &other) const
{
return trgm == other.trgm;
}
bool operator<(const Trigram &other) const
{
return trgm < other.trgm;
}
};
inline uint32_t hash_trigram(uint32_t trgm, uint32_t ht_size)
{
// CRC-like computation.
uint32_t crc = trgm;
for (int i = 0; i < 32; i++) {
bool bit = crc & 0x80000000;
crc <<= 1;
if (bit) {
crc ^= 0x1edc6f41;
}
}
return crc % ht_size;
}
#endif // !defined(DB_H)
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