1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/bitops.h>
4 #include <linux/string.h>
5 #include <asm/unaligned.h>
8 #include <valgrind/memcheck.h>
14 * bch2_varint_encode - encode a variable length integer
15 * @out - destination to encode to
16 * @v - unsigned integer to encode
18 * Returns the size in bytes of the encoded integer - at most 9 bytes
20 int bch2_varint_encode(u8 *out, u64 v)
22 unsigned bits = fls64(v|1);
23 unsigned bytes = DIV_ROUND_UP(bits, 7);
25 if (likely(bytes < 9)) {
27 v |= ~(~0 << (bytes - 1));
29 memcpy(out, &v, bytes);
33 put_unaligned_le64(v, out);
40 * bch2_varint_decode - encode a variable length integer
41 * @in - varint to decode
42 * @end - end of buffer to decode from
43 * @out - on success, decoded integer
45 * Returns the size in bytes of the decoded integer - or -1 on failure (would
46 * have read past the end of the buffer)
48 int bch2_varint_decode(const u8 *in, const u8 *end, u64 *out)
50 unsigned bytes = likely(in < end)
55 if (unlikely(in + bytes > end))
58 if (likely(bytes < 9)) {
60 memcpy(&v, in, bytes);
64 v = get_unaligned_le64(++in);
72 * bch2_varint_encode_fast - fast version of bch2_varint_encode
74 * This version assumes it's always safe to write 8 bytes to @out, even if the
75 * encoded integer would be smaller.
77 int bch2_varint_encode_fast(u8 *out, u64 v)
79 unsigned bits = fls64(v|1);
80 unsigned bytes = DIV_ROUND_UP(bits, 7);
82 if (likely(bytes < 9)) {
84 v |= ~(~0 << (bytes - 1));
90 put_unaligned_le64(v, out);
95 * bch2_varint_decode_fast - fast version of bch2_varint_decode
97 * This version assumes that it is safe to read at most 8 bytes past the end of
98 * @end (we still return an error if the varint extends past @end).
100 int bch2_varint_decode_fast(const u8 *in, const u8 *end, u64 *out)
102 #ifdef CONFIG_VALGRIND
103 VALGRIND_MAKE_MEM_DEFINED(in, 8);
105 u64 v = get_unaligned_le64(in);
106 unsigned bytes = ffz(*in) + 1;
108 if (unlikely(in + bytes > end))
111 if (likely(bytes < 9)) {
113 v &= ~(~0ULL << (7 * bytes));
115 v = get_unaligned_le64(++in);