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| author | John Naylor <john.naylor@postgresql.org> | 2025-01-15 13:28:26 +0700 |
|---|---|---|
| committer | John Naylor <john.naylor@postgresql.org> | 2025-01-17 16:29:25 +0700 |
| commit | e24d77080b365265f3c854f64e71518622883678 (patch) | |
| tree | 87872eb12aa444393037b26776b0821393e0d399 /src/backend/utils/adt/encode.c | |
| parent | 0869ea43e9c2257819e5c8719e28fe3b5c527911 (diff) | |
| download | postgresql-e24d77080b365265f3c854f64e71518622883678.tar.gz postgresql-e24d77080b365265f3c854f64e71518622883678.zip | |
Speed up hex_encode with bytewise lookup
Previously, hex_encode looked up each nibble of the input
separately. We now use a larger lookup table containing the two-byte
encoding of every possible input byte, resulting in a 1/3 reduction
in encoding time.
Reviewed by Tom Lane, Michael Paquier, Nathan Bossart, David Rowley
Discussion: https://postgr.es/m/CANWCAZZvXuJMgqMN4u068Yqa19CEjS31tQKZp_qFFFbgYfaXqQ%40mail.gmail.com
Diffstat (limited to 'src/backend/utils/adt/encode.c')
| -rw-r--r-- | src/backend/utils/adt/encode.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/src/backend/utils/adt/encode.c b/src/backend/utils/adt/encode.c index 4a6fcb56cd9..4ccaed815d1 100644 --- a/src/backend/utils/adt/encode.c +++ b/src/backend/utils/adt/encode.c @@ -145,7 +145,26 @@ binary_decode(PG_FUNCTION_ARGS) * HEX */ -static const char hextbl[] = "0123456789abcdef"; +/* + * The hex expansion of each possible byte value (two chars per value). + */ +static const char hextbl[512] = +"000102030405060708090a0b0c0d0e0f" +"101112131415161718191a1b1c1d1e1f" +"202122232425262728292a2b2c2d2e2f" +"303132333435363738393a3b3c3d3e3f" +"404142434445464748494a4b4c4d4e4f" +"505152535455565758595a5b5c5d5e5f" +"606162636465666768696a6b6c6d6e6f" +"707172737475767778797a7b7c7d7e7f" +"808182838485868788898a8b8c8d8e8f" +"909192939495969798999a9b9c9d9e9f" +"a0a1a2a3a4a5a6a7a8a9aaabacadaeaf" +"b0b1b2b3b4b5b6b7b8b9babbbcbdbebf" +"c0c1c2c3c4c5c6c7c8c9cacbcccdcecf" +"d0d1d2d3d4d5d6d7d8d9dadbdcdddedf" +"e0e1e2e3e4e5e6e7e8e9eaebecedeeef" +"f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"; static const int8 hexlookup[128] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, @@ -165,9 +184,11 @@ hex_encode(const char *src, size_t len, char *dst) while (src < end) { - *dst++ = hextbl[(*src >> 4) & 0xF]; - *dst++ = hextbl[*src & 0xF]; + unsigned char usrc = *((const unsigned char *) src); + + memcpy(dst, &hextbl[2 * usrc], 2); src++; + dst += 2; } return (uint64) len * 2; } |