From 86f49cc9da61004ddf37398d1b68205813dad08f Mon Sep 17 00:00:00 2001
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Tue, 30 Jan 2018 10:26:00 +0100
Subject: [PATCH] Added ICAP CRC and ECC calculations and tests

Signed-off-by: Herbert Poetzl <herbert@13thfloor.at>
---
 lib/CMakeLists.txt                         |  4 +-
 lib/include/prjxray/xilinx/xc7series/crc.h | 32 ++++++++++++++
 lib/include/prjxray/xilinx/xc7series/ecc.h | 50 ++++++++++++++++++++++
 lib/xilinx/xc7series/crc_test.cc           | 13 ++++++
 lib/xilinx/xc7series/ecc_test.cc           | 15 +++++++
 5 files changed, 113 insertions(+), 1 deletion(-)
 create mode 100644 lib/include/prjxray/xilinx/xc7series/crc.h
 create mode 100644 lib/include/prjxray/xilinx/xc7series/ecc.h
 create mode 100644 lib/xilinx/xc7series/crc_test.cc
 create mode 100644 lib/xilinx/xc7series/ecc_test.cc

diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 4b751d68..81735b56 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -53,7 +53,9 @@ if (PRJXRAY_BUILD_TESTING)
 		xilinx/xc7series/configuration_packetizer_test.cc
 		xilinx/xc7series/global_clock_region_test.cc
 		xilinx/xc7series/part_test.cc
-		xilinx/xc7series/row_test.cc)
+		xilinx/xc7series/row_test.cc
+		xilinx/xc7series/crc_test.cc
+		xilinx/xc7series/ecc_test.cc)
 	target_link_libraries(xilinx_xc7series_test libprjxray gtest_main)
 	add_test(NAME xilinx_xc7series_test
 		 COMMAND xilinx_xc7series_test
diff --git a/lib/include/prjxray/xilinx/xc7series/crc.h b/lib/include/prjxray/xilinx/xc7series/crc.h
new file mode 100644
index 00000000..81daacc4
--- /dev/null
+++ b/lib/include/prjxray/xilinx/xc7series/crc.h
@@ -0,0 +1,32 @@
+#ifndef PRJXRAY_LIB_XILINX_XC7SERIES_CRC_H_
+#define PRJXRAY_LIB_XILINX_XC7SERIES_CRC_H_
+
+#include <cstdint>
+
+namespace prjxray {
+namespace xilinx {
+namespace xc7series {
+
+// Extend the current CRC value with one address (5bit) and data (32bit) 
+// pair and return the newly computed CRC value
+
+uint32_t icap_crc(uint32_t addr, uint32_t data, uint32_t prev) {
+	uint64_t val = ((uint64_t)addr << 32) | data;
+	uint64_t crc = prev;
+	uint64_t poly = 0x82F63B78L << 1;	// CRC-32C (Castagnoli)
+
+	for (int i = 0; i < 37; i++) {
+		if ((val & 1) != (crc & 1))
+			crc ^= poly;
+
+		val >>= 1;
+		crc >>= 1;
+	}
+	return crc;
+}
+
+}  // namespace xc7series
+}  // namespace xilinx
+}  // namespace prjxray
+
+#endif  // PRJXRAY_LIB_XILINX_XC7SERIES_CRC_H_
diff --git a/lib/include/prjxray/xilinx/xc7series/ecc.h b/lib/include/prjxray/xilinx/xc7series/ecc.h
new file mode 100644
index 00000000..a9ecf0d6
--- /dev/null
+++ b/lib/include/prjxray/xilinx/xc7series/ecc.h
@@ -0,0 +1,50 @@
+#ifndef PRJXRAY_LIB_XILINX_XC7SERIES_ECC_H_
+#define PRJXRAY_LIB_XILINX_XC7SERIES_ECC_H_
+
+#include <cstdint>
+
+namespace prjxray {
+namespace xilinx {
+namespace xc7series {
+
+// Extend the current ECC code with one data word (32 bit) at a given
+// index in the configuration packet and return the new ECC code.
+
+uint32_t icap_ecc(uint32_t idx, uint32_t data, uint32_t ecc) {
+	uint32_t off = idx * 32;
+
+	if (idx > 0x25)			// avoid 0x800
+		off += 0x1360;
+	else if (idx > 0x6)		// avoid 0x400
+		off += 0x1340;
+	else				// avoid lower
+		off += 0x1320;
+
+
+	if (idx == 0x32)		// mask ECC
+		data &= 0xFFFFE000;
+
+	for (int i = 0; i < 32; i++) {
+		if (data & 1)
+			ecc ^= off + i;
+
+		data >>= 1;
+	}
+
+	if (idx == 0x64) {		// last index
+		uint32_t v = ecc & 0xFFF;
+		v ^= v >> 8;
+		v ^= v >> 4;
+		v ^= v >> 2;
+		v ^= v >> 1;
+		ecc ^= (v & 1) << 12;	// parity
+	}
+
+	return ecc;
+}
+
+}  // namespace xc7series
+}  // namespace xilinx
+}  // namespace prjxray
+
+#endif  // PRJXRAY_LIB_XILINX_XC7SERIES_ECC_H_
diff --git a/lib/xilinx/xc7series/crc_test.cc b/lib/xilinx/xc7series/crc_test.cc
new file mode 100644
index 00000000..72e6ef3c
--- /dev/null
+++ b/lib/xilinx/xc7series/crc_test.cc
@@ -0,0 +1,13 @@
+#include <prjxray/xilinx/xc7series/crc.h>
+
+#include <gtest/gtest.h>
+
+namespace xc7series = prjxray::xilinx::xc7series;
+
+TEST(IcapCrcTest, SimpleTests) {
+	EXPECT_EQ(xc7series::icap_crc(0, 0, 0), (uint32_t)0x0);
+	EXPECT_EQ(xc7series::icap_crc(~0, ~0, 0), 0xBF86D4DF);
+	EXPECT_EQ(xc7series::icap_crc(0, 0, ~0), 0xC631E365);
+	EXPECT_EQ(xc7series::icap_crc(1 << 4, 0, 0), 0x82F63B78);
+}
+
diff --git a/lib/xilinx/xc7series/ecc_test.cc b/lib/xilinx/xc7series/ecc_test.cc
new file mode 100644
index 00000000..de53a31b
--- /dev/null
+++ b/lib/xilinx/xc7series/ecc_test.cc
@@ -0,0 +1,15 @@
+#include <prjxray/xilinx/xc7series/ecc.h>
+
+#include <gtest/gtest.h>
+
+namespace xc7series = prjxray::xilinx::xc7series;
+
+TEST(IcapEccTest, SimpleTests) {
+	EXPECT_EQ(xc7series::icap_ecc(0, 0, 0), (uint32_t)0x0);
+	EXPECT_EQ(xc7series::icap_ecc(0, 1, 0), (uint32_t)0x1320);
+	EXPECT_EQ(xc7series::icap_ecc(0x7, 1, 0), (uint32_t)0x1420);
+	EXPECT_EQ(xc7series::icap_ecc(0x26, 1, 0), (uint32_t)0x1820);
+	EXPECT_EQ(xc7series::icap_ecc(0x32, ~0, 0), (uint32_t)0x000019AC);
+	EXPECT_EQ(xc7series::icap_ecc(0x64, 0, 1), (uint32_t)0x00001001);
+}
+