From 145f8fbfc010548dda353e5897b9d082e5bd4ddb Mon Sep 17 00:00:00 2001
From: tezc <ozantezcan@gmail.com>
Date: Fri, 4 Feb 2022 22:32:17 +0300
Subject: [PATCH] CRC32c doc

---
 crc32/README.md  | 7 ++++---
 crc32/sc_crc32.c | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/crc32/README.md b/crc32/README.md
index 8e3a57f..2c1a444 100644
--- a/crc32/README.md
+++ b/crc32/README.md
@@ -11,7 +11,7 @@
 include(CheckCCompilerFlag)
 include (TestBigEndian)
 
-# detect x86
+# Detect x86 and sse4.2 support
 check_c_compiler_flag(-msse4.2 HAVE_CRC32_HARDWARE)
 if (${HAVE_CRC32_HARDWARE})
   message(STATUS "CPU have -msse4.2, defined HAVE_CRC32C")
@@ -19,14 +19,15 @@ if (${HAVE_CRC32_HARDWARE})
   target_compile_definitions(${PROJECT_NAME}_test PRIVATE -DHAVE_CRC32C)
 endif ()
 
-# detect aarch64
+# Detect aarch64 and set march=armv8.1-a. armv7 doesn't have CRC32c instruction
+# so, armv7 will be unsupported with this flag. 
 if (CMAKE_SYSTEM_PROCESSOR STREQUAL aarch64)
   message(STATUS "CPU = aarch64, defined HAVE_CRC32C, -march=armv8.1-a")
   target_compile_definitions(${PROJECT_NAME}_test PRIVATE -DHAVE_CRC32C)
   target_compile_options(${PROJECT_NAME}_test PRIVATE -march=armv8.1-a)
 endif()
 
-# detect software version endianness
+# Detect software version endianness
 test_big_endian(HAVE_BIG_ENDIAN)
 if (${HAVE_BIG_ENDIAN})
   message(STATUS "System is BIG ENDIAN")
diff --git a/crc32/sc_crc32.c b/crc32/sc_crc32.c
index 7563225..58e750d 100644
--- a/crc32/sc_crc32.c
+++ b/crc32/sc_crc32.c
@@ -26,7 +26,7 @@
  * Version history:
  * 1.0  10 Feb 2013  First version
  * 1.1   1 Aug 2013  Correct comments on why three crc instructions in parallel
- * 1.2         2020  added gcc intrinsics, fixed undefined behaviour
+ * 1.2         2020  Added gcc intrinsics, fixed undefined behaviour
  * 1.3         2021  Added big endian support, added aarch64 crc32c support
  */