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authorChris Mason <chris.mason@fusionio.com>2012-07-25 15:02:07 -0400
committerChris Mason <chris.mason@fusionio.com>2012-07-26 14:51:27 -0400
commit71687d74d08b1e27fb9d81562e03fa1de6790775 (patch)
tree4b05925a4bd253a4716668df0b9343927487b912 /crc32c.c
parentc1690a383221c853939245646dca04ea912416c6 (diff)
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Use intel hardware crc32c where available
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Diffstat (limited to 'crc32c.c')
-rw-r--r--crc32c.c125
1 files changed, 123 insertions, 2 deletions
diff --git a/crc32c.c b/crc32c.c
index 4dc5f9c..a761a1d 100644
--- a/crc32c.c
+++ b/crc32c.c
@@ -9,6 +9,123 @@
*/
#include "kerncompat.h"
#include "crc32c.h"
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+u32 __crc32c_le(u32 crc, unsigned char const *data, size_t length);
+static u32 (*crc_function)(u32 crc, unsigned char const *data, size_t length) = __crc32c_le;
+
+#ifdef __x86_64__
+
+/*
+ * Based on a posting to lkml by Austin Zhang <austin.zhang@intel.com>
+ *
+ * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
+ * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
+ * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
+ * http://www.intel.com/products/processor/manuals/
+ * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ * Volume 2A: Instruction Set Reference, A-M
+ */
+#if __SIZEOF_LONG__ == 8
+#define REX_PRE "0x48, "
+#define SCALE_F 8
+#else
+#define REX_PRE
+#define SCALE_F 4
+#endif
+
+static int crc32c_probed = 0;
+static int crc32c_intel_available = 0;
+
+static uint32_t crc32c_intel_le_hw_byte(uint32_t crc, unsigned char const *data,
+ unsigned long length)
+{
+ while (length--) {
+ __asm__ __volatile__(
+ ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
+ :"=S"(crc)
+ :"0"(crc), "c"(*data)
+ );
+ data++;
+ }
+
+ return crc;
+}
+
+/*
+ * Steps through buffer one byte at at time, calculates reflected
+ * crc using table.
+ */
+uint32_t crc32c_intel(u32 crc, unsigned char const *data, unsigned long length)
+{
+ unsigned int iquotient = length / SCALE_F;
+ unsigned int iremainder = length % SCALE_F;
+ unsigned long *ptmp = (unsigned long *)data;
+
+ while (iquotient--) {
+ __asm__ __volatile__(
+ ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
+ :"=S"(crc)
+ :"0"(crc), "c"(*ptmp)
+ );
+ ptmp++;
+ }
+
+ if (iremainder)
+ crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
+ iremainder);
+
+ return crc;
+}
+
+static void do_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
+ unsigned int *edx)
+{
+ int id = *eax;
+
+ asm("movl %4, %%eax;"
+ "cpuid;"
+ "movl %%eax, %0;"
+ "movl %%ebx, %1;"
+ "movl %%ecx, %2;"
+ "movl %%edx, %3;"
+ : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
+ : "r" (id)
+ : "eax", "ebx", "ecx", "edx");
+}
+
+void crc32c_intel_probe(void)
+{
+ if (!crc32c_probed) {
+ unsigned int eax, ebx, ecx, edx;
+
+ eax = 1;
+
+ do_cpuid(&eax, &ebx, &ecx, &edx);
+ crc32c_intel_available = (ecx & (1 << 20)) != 0;
+ crc32c_probed = 1;
+ }
+}
+
+int crc32c_optimization_init(void)
+{
+ crc32c_intel_probe();
+ if (crc32c_intel_available)
+ crc_function = crc32c_intel;
+}
+#else
+
+int crc32c_optimization_init(void)
+{
+}
+
+#endif /* __x86_64__ */
/*
* This is the CRC-32C table
@@ -91,11 +208,15 @@ static const u32 crc32c_table[256] = {
* crc using table.
*/
-u32 crc32c_le(u32 crc, unsigned char const *data, size_t length)
+u32 __crc32c_le(u32 crc, unsigned char const *data, size_t length)
{
while (length--)
crc =
crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8);
-
return crc;
}
+
+u32 crc32c_le(u32 crc, unsigned char const *data, size_t length)
+{
+ return crc_function(crc, data, length);
+}