Uses the fast crc32 instruction if SSE4.2 is available.

cpu.h

@@ -20,12 +20,6 @@
 
 #if defined(__i386__) || defined(__x86_64__)
 
-#define X86_FEATURE_MMX (0*32+23) /* Multimedia Extensions */
-#define X86_FEATURE_FXSR (0*32+24) /* FXSAVE and FXRSTOR instructions (fast save and restore) */
-#define X86_FEATURE_XMM (0*32+25) /* Streaming SIMD Extensions */
-#define X86_FEATURE_XMM2 (0*32+26) /* Streaming SIMD Extensions-2 */
-#define X86_FEATURE_MMXEXT (1*32+22) /* AMD MMX extensions */
-
 static inline void cpuid(uint32_t func, uint32_t* reg)
 {
 	asm volatile(
@@ -44,15 +38,6 @@ static inline void cpuid(uint32_t func, uint32_t* reg)
 	);
 }
 
-static inline int cpu_has(uint32_t flag)
-{
-	uint32_t reg[4];
-
-	cpuid((flag >> 5) ? 0x80000001 : 1, reg);
-
-	return (reg[3] >> (flag & 31)) & 1;
-}
-
 #define CPU_VENDOR_MAX 13
 
 static inline void cpu_info(char* vendor, unsigned* family, unsigned* model)
@@ -90,15 +75,29 @@ static inline void cpu_info(char* vendor, unsigned* family, unsigned* model)
 
 static inline int cpu_has_mmx(void)
 {
-	return cpu_has(X86_FEATURE_MMX);
+	uint32_t reg[4];
+
+	cpuid(1, reg);
+
+	return (reg[3] >> 23) & 1;
 }
 
 static inline int cpu_has_sse2(void)
 {
-	return cpu_has(X86_FEATURE_MMX) &&
-		cpu_has(X86_FEATURE_FXSR) &&
-		cpu_has(X86_FEATURE_XMM) &&
-		cpu_has(X86_FEATURE_XMM2);
+	uint32_t reg[4];
+
+	cpuid(1, reg);
+
+	return (reg[3] >> 26) & 1;
+}
+
+static inline int cpu_has_sse42(void)
+{
+	uint32_t reg[4];
+
+	cpuid(1, reg);
+
+	return (reg[2] >> 20) & 1;
 }
 
 /**

snapraid.c

@@ -470,6 +470,7 @@ int main(int argc, char* argv[])
 	}
 
 	raid_init();
+	crc32c_init();
 
 	if (!opt.skip_self)
 		selftest(opt.gui);

util.c

@@ -18,6 +18,7 @@
 #include "portable.h"
 
 #include "util.h"
+#include "cpu.h"
 
 /****************************************************************************/
 /* hex conversion table */
@@ -855,16 +856,50 @@ static uint32_t CRC32C[256] = {
 	0xbe2da0a5, 0x4c4623a6, 0x5f16d052, 0xad7d5351
 };
 
-uint32_t crc32c(uint32_t crc, const unsigned char* ptr, unsigned size)
+static uint32_t crc32c_gen(uint32_t crc, const unsigned char* ptr, unsigned size)
 {
-	unsigned i;
-
-	for(i=0;i<size;++i)
-		crc = CRC32C[(crc ^ ptr[i]) & 0xff] ^ (crc >> 8);
+	while (size) {
+		crc = CRC32C[(crc ^ *ptr) & 0xff] ^ (crc >> 8);
+		++ptr;
+		--size;
+	}
 
 	return crc;
 }
 
+#if defined(__i386__) || defined(__x86_64__)
+
+static uint32_t crc32c_x86(uint32_t crc, const unsigned char* ptr, unsigned size)
+{
+	while (size >= 4) {
+		asm volatile ("crc32l %1, %0\n" : "+r" (crc) : "rm" (*(uint32_t*)ptr));
+		ptr += 4;
+		size -= 4;
+	}
+
+	while (size) {
+		asm volatile ("crc32b %1, %0\n" : "+r" (crc) : "rm" (*ptr));
+		++ptr;
+		--size;
+	}
+
+	return crc;
+}
+
+#endif
+
+uint32_t (*crc32c)(uint32_t crc, const unsigned char* ptr, unsigned size);
+
+void crc32c_init(void)
+{
+	crc32c = crc32c_gen;
+#if defined(__i386__) || defined(__x86_64__)
+	if (cpu_has_sse42()) {
+		crc32c = crc32c_x86;
+	}
+#endif
+}
+
 /****************************************************************************/
 /* path */
 

util.h

@@ -499,7 +499,12 @@ void randomize(void* ptr, unsigned size);
 /**
  * Computes the CRC-32 (Castagnoli)
  */
-uint32_t crc32c(uint32_t crc, const unsigned char* ptr, unsigned size);
+uint32_t (*crc32c)(uint32_t crc, const unsigned char* ptr, unsigned size);
+
+/**
+ * Initializes the CRC-32 (Castagnoli) support.
+ */
+void crc32c_init(void);
 
 /****************************************************************************/
 /* sax */