Move input xor to ChaCha_OperateKeystream_SSE2

This picks up about 0.2 cpb in ChaCha::OperateKeystream. It may not sound like much but it puts SSE2 intrinsics version on par with the ASM version of Salsa20. Salsa20 leads ChaCha by 0.1 to 0.15 cpb, which equates to about 50 MB/s.

1 files changed, 15 insertions, 9 deletions

diff --git a/chacha.cpp b/chacha.cpp
index 7293c2a9..080ccbfd 100644
--- a/chacha.cpp
+++ b/chacha.cpp
@@ -12,11 +12,7 @@
 NAMESPACE_BEGIN(CryptoPP)

 

 #if (CRYPTOPP_SSE2_INTRIN_AVAILABLE || CRYPTOPP_SSE2_ASM_AVAILABLE)

-extern void ChaCha_OperateKeystream_SSE2(const word32 *state, byte *message, unsigned int rounds);

-#endif

-

-#if (CRYPTOPP_ARM_NEON_AVAILABLE)

-extern void ChaCha_OperateKeystream_NEON(const word32 *state, byte *message, unsigned int rounds);

+extern void ChaCha_OperateKeystream_SSE2(const word32 *state, const byte* input, byte *output, unsigned int rounds, bool xorInput);

 #endif

 

 #define CHACHA_QUARTER_ROUND(a,b,c,d) \

@@ -38,6 +34,10 @@ std::string ChaCha_Policy::AlgorithmProvider() const
 	if (HasSSE2())

 		return "SSE2";

 #endif

+#if (CRYPTOPP_ARM_NEON_AVAILABLE)

+	if (HasNEON())

+		return "NEON";

+#endif

 	return "C++";

 }

 

@@ -96,9 +96,17 @@ unsigned int ChaCha_Policy::GetOptimalBlockSize() const
 		return 4*BYTES_PER_ITERATION;

 	else

 #endif

+#if (CRYPTOPP_ARM_NEON_AVAILABLE)

+	if (HasNEON())

+		return 4*BYTES_PER_ITERATION;

+	else

+#endif

 		return BYTES_PER_ITERATION;

 }

 

+// OperateKeystream always produces a key stream. The key stream is written

+// to output. Optionally a message may be supplied to xor with the key stream.

+// The message is input, and output = output ^ input.

 void ChaCha_Policy::OperateKeystream(KeystreamOperation operation,

         byte *output, const byte *input, size_t iterationCount)

 {

@@ -107,10 +115,8 @@ void ChaCha_Policy::OperateKeystream(KeystreamOperation operation,
 	{

 		while (iterationCount >= 4)

 		{

-			ChaCha_OperateKeystream_SSE2(m_state, output, m_rounds);

-

-			if ((operation & INPUT_NULL) != INPUT_NULL)

-				xorbuf(output, input, 4*BYTES_PER_ITERATION);

+			bool xorInput = (operation & INPUT_NULL) != INPUT_NULL;

+			ChaCha_OperateKeystream_SSE2(m_state, input, output, m_rounds, xorInput);

 

 			m_state[12] += 4;

 			if (m_state[12] < 4)