hash/crc32: clarify documentation
Explicitly specify that we represent polynomial in reversed notation
Fixes #8229
Change-Id: Idf094c01fd82f133cd0c1b50fa967d12c577bdb5
Reviewed-on: https://go-review.googlesource.com/9237
Reviewed-by: David Chase <drchase@google.com>
diff --git a/src/hash/crc32/crc32.go b/src/hash/crc32/crc32.go
index 6a6b947..4b13c12 100644
--- a/src/hash/crc32/crc32.go
+++ b/src/hash/crc32/crc32.go
@@ -5,6 +5,18 @@
// Package crc32 implements the 32-bit cyclic redundancy check, or CRC-32,
// checksum. See http://en.wikipedia.org/wiki/Cyclic_redundancy_check for
// information.
+//
+// Polynomials are represented in LSB-first form also known as reversed representation.
+//
+// LSB-first representation is a hexadecimal number with n bits, the most
+// significant bit represents the coefficient of x^0 and the least significant
+// bit represents the coefficient of x^(n-1).
+//
+// For example, x^5 + x^2 + x^0 is (binary:10100, hexadecimal:0x14) in 5-bit LSB-first form,
+// as opposed to (binary:00101, hexadecimal:0x05) in MSB-first (normal) form.
+//
+// See http://en.wikipedia.org/wiki/Mathematics_of_cyclic_redundancy_checks#Reversed_representations_and_reciprocal_polynomials
+// for information.
package crc32
import (
