From 3ed1d9e24a7784bd9857fc84b3f5e69f493a7c5a Mon Sep 17 00:00:00 2001
From: Jared Boone <jboone@earfeast.com>
Date: Tue, 5 Jul 2016 12:06:51 -0700
Subject: [PATCH] CPLD: Method to calculate bitstream CRC32.

---
 firmware/common/cpld_max5.cpp | 18 ++++++++++++++++++
 firmware/common/cpld_max5.hpp |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/firmware/common/cpld_max5.cpp b/firmware/common/cpld_max5.cpp
index b6c4f6c5..f0c13d68 100644
--- a/firmware/common/cpld_max5.cpp
+++ b/firmware/common/cpld_max5.cpp
@@ -114,6 +114,13 @@ bool CPLD::verify(
 	return block_0_success && block_1_success;
 }
 
+uint32_t CPLD::crc() {
+	crc_t crc { 0x04c11db7, 0xffffffff, 0xffffffff };
+	block_crc(0, 3328, crc);
+	block_crc(1,  512, crc);
+	return crc.checksum();
+}
+
 void CPLD::sector_select(const uint16_t id) {
 	shift_ir(0x203);			// Sector select
 	jtag.runtest_tck(93);		// 5us
@@ -219,6 +226,17 @@ bool CPLD::is_blank_block(const uint16_t id, const size_t count) {
 	return success;
 }
 
+void CPLD::block_crc(const uint16_t id, const size_t count, crc_t& crc) {
+	sector_select(id);
+	shift_ir(0x205);			// Read
+	jtag.runtest_tck(93);		// 5us
+
+	for(size_t i=0; i<count; i++) {
+		const uint16_t from_device = jtag.shift_dr(16, 0xffff);
+		crc.process_bytes(&from_device, sizeof(from_device));
+	}
+}
+
 bool CPLD::is_blank() {
 	const auto block_0_blank = is_blank_block(0x0000, 3328);
 	const auto block_1_blank = is_blank_block(0x0001, 512);
diff --git a/firmware/common/cpld_max5.hpp b/firmware/common/cpld_max5.hpp
index 199bd31a..6a206b64 100644
--- a/firmware/common/cpld_max5.hpp
+++ b/firmware/common/cpld_max5.hpp
@@ -23,6 +23,7 @@
 #define __CPLD_MAX5_H__
 
 #include "jtag.hpp"
+#include "crc.hpp"
 
 #include <cstdint>
 #include <cstddef>
@@ -75,6 +76,8 @@ public:
 
 	bool is_blank();
 
+	uint32_t crc();
+
 	std::pair<bool, uint8_t> boundary_scan();
 
 	enum class Instruction {
@@ -135,6 +138,9 @@ private:
 
 	bool is_blank_block(const uint16_t id, const size_t count);
 
+	using crc_t = CRC<32, true, true>;
+	void block_crc(const uint16_t id, const size_t count, crc_t& crc);
+	
 	const uint32_t IDCODE = 0b00000010000010100101000011011101;
 
 	const size_t IR_LENGTH = 10;