From: Yikun Jiang <yikunk...@gmail.com>
Implement CRC function using inline assembly instructions
instead of crc_32_tab to improve the performance in aarch64.
---
util.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/util.c b/util.c
index 79fe505..d978c61 100644
--- a/util.c
+++ b/util.c
@@ -32,6 +32,17 @@
#include <dirname.h>
#include <xalloc.h>
+/* ========================================================================
+ * Implement CRC function using inline assembly instructions instead of
+ * crc_32_tab in aarch64.
+ */
+#ifdef __aarch64__
+# define CRC32D(crc, value) __asm__("crc32x %w[c], %w[c],
%x[v]":[c]"+r"(crc):[v]"r"(value))
+# define CRC32W(crc, value) __asm__("crc32w %w[c], %w[c],
%w[v]":[c]"+r"(crc):[v]"r"(value))
+# define CRC32H(crc, value) __asm__("crc32h %w[c], %w[c],
%w[v]":[c]"+r"(crc):[v]"r"(value))
+# define CRC32B(crc, value) __asm__("crc32b %w[c], %w[c],
%w[v]":[c]"+r"(crc):[v]"r"(value))
+#endif
+
#ifndef CHAR_BIT
# define CHAR_BIT 8
#endif
@@ -41,6 +52,7 @@ static int write_buffer (int, voidp, unsigned int);
/* ========================================================================
* Table of CRC-32's of all single-byte values (made by makecrc.c)
*/
+#ifndef __aarch64__
static const ulg crc_32_tab[] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
@@ -95,6 +107,7 @@ static const ulg crc_32_tab[] = {
0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
0x2d02ef8dL
};
+#endif
/* Shift register contents. */
static ulg crc = 0xffffffffL;
@@ -134,6 +147,42 @@ ulg updcrc(s, n)
{
register ulg c; /* temporary variable */
+#ifdef __aarch64__
+ register const uint8_t *buf1;
+ register const uint16_t *buf2;
+ register const uint32_t *buf4;
+ register const uint64_t *buf8;
+ int64_t length = (int64_t)n;
+ buf8 = (const uint64_t *)(const void *)s;
+
+ if (s == NULL) {
+ c = 0xffffffffL;
+ } else {
+ c = crc;
+ while(length >= sizeof(uint64_t)) {
+ CRC32D(c, *buf8++);
+ length -= sizeof(uint64_t);
+ }
+
+ buf4 = (const uint32_t *)(const void *)buf8;
+ if (length >= sizeof(uint32_t)) {
+ CRC32W(c, *buf4++);
+ length -= sizeof(uint32_t);
+ }
+
+ buf2 = (const uint16_t *)(const void *)buf4;
+ if(length >= sizeof(uint16_t)) {
+ CRC32H(c, *buf2++);
+ length -= sizeof(uint16_t);
+ }
+
+ buf1 = (const uint8_t *)(const void *)buf2;
+ if (length >= sizeof(uint8_t)) {
+ CRC32B(c, *buf1);
+ length -= sizeof(uint8_t);
+ }
+ }
+#else
if (s == NULL) {
c = 0xffffffffL;
} else {
@@ -142,6 +191,7 @@ ulg updcrc(s, n)
c = crc_32_tab[((int)c ^ (*s++)) & 0xff] ^ (c >> 8);
} while (--n);
}
+#endif
crc = c;
return c ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */
}
--
2.17.1
