Add SSE4 based SHA256

src/Makefile.am

@@ -269,6 +269,7 @@ crypto_libdogecoin_crypto_la_SOURCES = \
   crypto/sha1.cpp \
   crypto/sha1.h \
   crypto/sha256.cpp \
+  crypto/sha256_sse4.cpp \
   crypto/sha256.h \
   crypto/sha512.cpp \
   crypto/sha512.h

src/crypto/sha256.cpp

@@ -4,11 +4,11 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "crypto/sha256.h"
-
 #include "crypto/common.h"
 #include "support/experimental.h"
 
 #include <string.h>
+#include <atomic>
 
 #if (defined(__ia64__) || defined(__x86_64__)) && \
     !defined(__APPLE__) && \
@@ -55,6 +55,14 @@ static const uint32_t K[] =
 };
 #endif  /** ARM Headers */
 
+#if defined(__x86_64__) || defined(__amd64__)
+#include <cpuid.h>
+namespace sha256_sse4
+{
+void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks);
+}
+#endif
+
 // Internal implementation code.
 namespace
 {
@@ -358,13 +366,16 @@ void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
 #define HWCAP_SHA2  (1<<6)
 #include <sys/auxv.h>
 #elif defined(__WIN64__)
-#include <intrin.h>
-bool isAVX (void) {
-  int cpuinfo[4];
-  __cpuid(cpuinfo, 1);
-  return ((cpuinfo[2] & (1 << 28)) != 0);
+#if (defined(__x86_64__) || defined(__amd64__) || defined(__i386__))
+/** Check whether the OS has enabled AVX registers. */
+bool AVXEnabled()
+{
+    uint32_t a, d;
+    __asm__("xgetbv" : "=a"(a), "=d"(d) : "c"(0));
+    return (a & 6) == 6;
 }
 #endif
+#endif
 
 /** Define a function pointer for Transform */
 void (*transform_ptr) (uint32_t*, const unsigned char*, size_t) = &Transform;
@@ -383,8 +394,14 @@ void inline Initialize_transform_ptr(void)
     if (__builtin_cpu_supports("avx2"))
        transform_ptr = &Transform_AVX2;
 #elif USE_AVX2 && defined(__WIN64__)
-    if (isAVX)
+    if (AVXEnabled)
        transform_ptr = &Transform_AVX2;
+#elif USE_ASM
+#if defined(__x86_64__) || defined(__amd64__)
+    uint32_t eax, ebx, ecx, edx;
+    if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) && (ecx >> 19) & 1)
+        transform_ptr = sha256_sse4::Transform;
+#endif
 #endif
 }