Add SHA256 dispatcher

Author: sipa

src/bench/bench_bitcoin.cpp

@@ -4,6 +4,7 @@
 
 #include "bench.h"
 
+#include "crypto/sha256.h"
 #include "key.h"
 #include "validation.h"
 #include "util.h"
@@ -12,6 +13,7 @@
 int
 main(int argc, char** argv)
 {
+    SHA256AutoDetect();
     RandomInit();
     ECC_Start();
     SetupEnvironment();

src/crypto/sha256.cpp

@@ -8,6 +8,8 @@
 
 #include <string.h>
 
+#include <atomic>
+
 // Internal implementation code.
 namespace
 {
@@ -131,8 +133,15 @@ void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
 }
 
 } // namespace sha256
+
+void (*Transform)(uint32_t*, const unsigned char*, size_t) = sha256::Transform;
+
 } // namespace
 
+std::string SHA256AutoDetect()
+{
+    return "standard";
+}
 
 ////// SHA-256
 
@@ -150,12 +159,12 @@ CSHA256& CSHA256::Write(const unsigned char* data, size_t len)
         memcpy(buf + bufsize, data, 64 - bufsize);
         bytes += 64 - bufsize;
         data += 64 - bufsize;
-        sha256::Transform(s, buf, 1);
+        Transform(s, buf, 1);
         bufsize = 0;
     }
     if (end - data >= 64) {
         size_t blocks = (end - data) / 64;
-        sha256::Transform(s, data, blocks);
+        Transform(s, data, blocks);
         data += 64 * blocks;
         bytes += 64 * blocks;
     }

src/crypto/sha256.h

@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string>
 
 /** A hasher class for SHA-256. */
 class CSHA256
@@ -25,4 +26,9 @@ class CSHA256
     CSHA256& Reset();
 };
 
+/** Autodetect the best available SHA256 implementation.
+ *  Returns the name of the implementation.
+ */
+std::string SHA256AutoDetect();
+
 #endif // BITCOIN_CRYPTO_SHA256_H

src/init.cpp

@@ -1161,6 +1161,8 @@ bool AppInitSanityChecks()
     // ********************************************************* Step 4: sanity checks
 
     // Initialize elliptic curve code
+    std::string sha256_algo = SHA256AutoDetect();
+    LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
     RandomInit();
     ECC_Start();
     globalVerifyHandle.reset(new ECCVerifyHandle());

src/test/test_bitcoin.cpp

@@ -7,6 +7,7 @@
 #include "chainparams.h"
 #include "consensus/consensus.h"
 #include "consensus/validation.h"
+#include "crypto/sha256.h"
 #include "fs.h"
 #include "key.h"
 #include "validation.h"
@@ -33,6 +34,7 @@ extern void noui_connect();
 
 BasicTestingSetup::BasicTestingSetup(const std::string& chainName)
 {
+        SHA256AutoDetect();
         RandomInit();
         ECC_Start();
         SetupEnvironment();