fix arm64 crc32 on old glibc/gcc.

patch by @sergey-dryabzhinsky on github, but he deleted the repo so I
rewrote the commit.

1 files changed, 6 insertions, 0 deletions

diff --git a/crc32c.c b/crc32c.c
index 916e0e6..26df879 100644
--- a/crc32c.c
+++ b/crc32c.c
@@ -276,6 +276,7 @@ void crc32c_init(void) {
 #elif defined(__aarch64__) && defined(__linux__)
 #include <sys/auxv.h>
 
+#if defined(HWCAP_CRC32)
 static inline uint32_t crc32cx(uint32_t crc, const uint64_t data)
 {
         asm(".arch_extension crc\n"
@@ -336,6 +337,11 @@ void crc32c_init(void) {
     if (auxv & HWCAP_CRC32)
         crc32c = crc32c_hw;
 }
+#else /* no hw crc32 on arm64 system supported? old compiler/libc/kernel? */
+void crc32c_init(void) {
+    crc32c = crc32c_sw;
+}
+#endif
 #else /* !__x86_64__i && !__aarch64__ */
 void crc32c_init(void) {
     crc32c = crc32c_sw;