From 71fba5c6662d6bbe74366c03b531a5f86b25bbbb Mon Sep 17 00:00:00 2001
From: "Pavel V. Shatov (Meister)" <meisterpaul1@yandex.ru>
Date: Mon, 26 Feb 2018 13:05:17 +0300
Subject: Initial commit of C reference model for ECDH cores.

---
 fpga_lowlevel.cpp | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 fpga_lowlevel.cpp

(limited to 'fpga_lowlevel.cpp')

diff --git a/fpga_lowlevel.cpp b/fpga_lowlevel.cpp
new file mode 100644
index 0000000..676d188
--- /dev/null
+++ b/fpga_lowlevel.cpp
@@ -0,0 +1,137 @@
+//------------------------------------------------------------------------------
+//
+// fpga_lowlevel.cpp
+// -----------------------------------
+// Models of Low-level FPGA primitives
+//
+// Authors: Pavel Shatov
+//
+// Copyright (c) 2015-2016, 2018 NORDUnet A/S
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// - Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+//
+// - Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+//
+// - Neither the name of the NORDUnet nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+//------------------------------------------------------------------------------
+
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+#include <stdint.h>
+#include "ecdh_fpga_model.h"
+#include "fpga_lowlevel.h"
+
+
+//------------------------------------------------------------------------------
+//
+// Low-level 32-bit adder with carry input and carry output.
+//
+// Carries are 1 bit wide.
+//
+// {c_out, s} = x + y + c_in
+//
+//------------------------------------------------------------------------------
+void fpga_lowlevel_add32(FPGA_WORD x, FPGA_WORD y, bool c_in, FPGA_WORD *s, bool *c_out)
+//------------------------------------------------------------------------------
+{
+		// calculate sum
+	FPGA_WORD_EXTENDED r = (FPGA_WORD_EXTENDED)x + (FPGA_WORD_EXTENDED)y;
+
+		// process carry input
+	if (c_in) r++;
+
+		// store sum
+	*s = (FPGA_WORD)r;
+
+		// shift sum to obtain carry flag
+	r >>= FPGA_WORD_WIDTH;
+
+		// store carry
+	*c_out = (r != 0);
+}
+
+
+//------------------------------------------------------------------------------
+//
+// Low-level 32-bit subtractor with borrow input and borrow output.
+//
+// Borrows are 1 bit wide.
+//
+// {b_out, d} = x - y - b_in
+//
+void fpga_lowlevel_sub32(FPGA_WORD x, FPGA_WORD y, bool b_in, FPGA_WORD *d, bool *b_out)
+//------------------------------------------------------------------------------
+{
+		// calculate difference
+	FPGA_WORD_EXTENDED r = (FPGA_WORD_EXTENDED)x - (FPGA_WORD_EXTENDED)y;
+
+		// process borrow input
+	if (b_in) r--;
+
+		// store difference
+	*d = (FPGA_WORD)r;
+
+		// shift difference to obtain borrow flag
+	r >>= FPGA_WORD_WIDTH;
+
+		// store borrow
+	*b_out = (r != 0);
+}
+
+
+//------------------------------------------------------------------------------
+//
+// Low-level 16x16-bit multiplier.
+//
+// Inputs are 16-bit wide, outputs are 32-bit wide.
+//
+// p = x * y
+//
+void fpga_lowlevel_mul16(FPGA_WORD_REDUCED x, FPGA_WORD_REDUCED y, FPGA_WORD *p)
+//------------------------------------------------------------------------------
+{
+		// multiply and store result
+	*p = (FPGA_WORD)x * (FPGA_WORD)y;
+}
+
+
+//------------------------------------------------------------------------------
+//
+// Low-level 48-bit adder without carries.
+//
+// s = (x + y)[47:0]
+//
+void fpga_lowlevel_add48(FPGA_WORD_EXTENDED x, FPGA_WORD_EXTENDED y, FPGA_WORD_EXTENDED *s)
+//------------------------------------------------------------------------------
+{
+		// add and store result truncated to 48 bits
+	*s = (x + y) & FPGA_MASK_ADDER48;
+}
+
+
+//------------------------------------------------------------------------------
+// End-of-File
+//------------------------------------------------------------------------------
-- 
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