| bseeniva | 0b9cbcb | 2026-02-12 19:11:11 +0530 | [diff] [blame] | 1 | // Copyright The OpenTelemetry Authors |
| 2 | // SPDX-License-Identifier: Apache-2.0 |
| 3 | |
| 4 | package trace // import "go.opentelemetry.io/otel/trace" |
| 5 | |
| 6 | const ( |
| 7 | // hexLU is a hex lookup table of the 16 lowercase hex digits. |
| 8 | // The character values of the string are indexed at the equivalent |
| 9 | // hexadecimal value they represent. This table efficiently encodes byte data |
| 10 | // into a string representation of hexadecimal. |
| 11 | hexLU = "0123456789abcdef" |
| 12 | |
| 13 | // hexRev is a reverse hex lookup table for lowercase hex digits. |
| 14 | // The table is efficiently decodes a hexadecimal string into bytes. |
| 15 | // Valid hexadecimal characters are indexed at their respective values. All |
| 16 | // other invalid ASCII characters are represented with '\xff'. |
| 17 | // |
| 18 | // The '\xff' character is used as invalid because no valid character has |
| 19 | // the upper 4 bits set. Meaning, an efficient validation can be performed |
| 20 | // over multiple character parsing by checking these bits remain zero. |
| 21 | hexRev = "" + |
| 22 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 23 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 24 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 25 | "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\xff\xff\xff\xff\xff\xff" + |
| 26 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 27 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 28 | "\xff\x0a\x0b\x0c\x0d\x0e\x0f\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 29 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 30 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 31 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 32 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 33 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 34 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 35 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 36 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" + |
| 37 | "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" |
| 38 | ) |