PEL: Add BCD time helpers for PELs

A PEL stores time in BCD, with a byte each for:
* year MSB
* year LSB
* month
* day
* hour
* minutes
* seconds
* hundredths

This commit adds a structure to represent this, and functions to:
* Create a BCD structure from a std::chrono::time_point
* Convert any number to BCD
* Write the BCD structure into a Stream
* Extract a BCD structure from a Stream

Refresher: The BCD value of 32 is 0x32.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I09ea4098f3a3981931f595d11fb63aff31d9fb0d

5 files changed, 241 insertions, 1 deletions

diff --git a/extensions/openpower-pels/bcd_time.cpp b/extensions/openpower-pels/bcd_time.cpp
new file mode 100644
index 0000000..bb80f1a
--- /dev/null
+++ b/extensions/openpower-pels/bcd_time.cpp
@@ -0,0 +1,61 @@
+#include "bcd_time.hpp"
+
+namespace openpower
+{
+namespace pels
+{
+
+bool BCDTime::operator==(const BCDTime& right) const
+{
+    return (yearMSB == right.yearMSB) && (yearLSB == right.yearLSB) &&
+           (month == right.month) && (day == right.day) &&
+           (hour == right.hour) && (minutes == right.minutes) &&
+           (seconds == right.seconds) && (hundredths == right.hundredths);
+}
+
+bool BCDTime::operator!=(const BCDTime& right) const
+{
+    return !(*this == right);
+}
+
+BCDTime getBCDTime(std::chrono::time_point<std::chrono::system_clock>& time)
+{
+    BCDTime bcd;
+
+    using namespace std::chrono;
+    time_t t = system_clock::to_time_t(time);
+    tm* localTime = localtime(&t);
+    assert(localTime != nullptr);
+
+    int year = 1900 + localTime->tm_year;
+    bcd.yearMSB = toBCD(year / 100);
+    bcd.yearLSB = toBCD(year % 100);
+    bcd.month = toBCD(localTime->tm_mon + 1);
+    bcd.day = toBCD(localTime->tm_mday);
+    bcd.hour = toBCD(localTime->tm_hour);
+    bcd.minutes = toBCD(localTime->tm_min);
+    bcd.seconds = toBCD(localTime->tm_sec);
+
+    auto ms = duration_cast<milliseconds>(time.time_since_epoch()).count();
+    int hundredths = (ms % 1000) / 10;
+    bcd.hundredths = toBCD(hundredths);
+
+    return bcd;
+}
+
+Stream& operator>>(Stream& s, BCDTime& time)
+{
+    s >> time.yearMSB >> time.yearLSB >> time.month >> time.day >> time.hour;
+    s >> time.minutes >> time.seconds >> time.hundredths;
+    return s;
+}
+
+Stream& operator<<(Stream& s, BCDTime& time)
+{
+    s << time.yearMSB << time.yearLSB << time.month << time.day << time.hour;
+    s << time.minutes << time.seconds << time.hundredths;
+    return s;
+}
+
+} // namespace pels
+} // namespace openpower
diff --git a/extensions/openpower-pels/bcd_time.hpp b/extensions/openpower-pels/bcd_time.hpp
new file mode 100644
index 0000000..e218756
--- /dev/null
+++ b/extensions/openpower-pels/bcd_time.hpp
@@ -0,0 +1,88 @@
+#pragma once
+#include "stream.hpp"
+
+#include <chrono>
+
+namespace openpower
+{
+namespace pels
+{
+
+/**
+ * @brief A structure that contains a PEL timestamp in BCD.
+ */
+struct BCDTime
+{
+    uint8_t yearMSB;
+    uint8_t yearLSB;
+    uint8_t month;
+    uint8_t day;
+    uint8_t hour;
+    uint8_t minutes;
+    uint8_t seconds;
+    uint8_t hundredths;
+
+    bool operator==(const BCDTime& right) const;
+    bool operator!=(const BCDTime& right) const;
+
+} __attribute__((packed));
+
+/**
+ * @brief Converts a time_point into a BCD time
+ *
+ * @param[in] time - the time_point to convert
+ * @return BCDTime - the BCD time
+ */
+BCDTime getBCDTime(std::chrono::time_point<std::chrono::system_clock>& time);
+
+/**
+ * @brief Converts a number to a BCD.
+ *
+ * For example 32 -> 0x32.
+ *
+ * Source: PLDM repository
+ *
+ * @param[in] value - the value to convert.
+ *
+ * @return T - the BCD value
+ */
+template <typename T>
+T toBCD(T decimal)
+{
+    T bcd = 0;
+    T remainder = 0;
+    auto count = 0;
+
+    while (decimal)
+    {
+        remainder = decimal % 10;
+        bcd = bcd + (remainder << count);
+        decimal = decimal / 10;
+        count += 4;
+    }
+
+    return bcd;
+}
+
+/**
+ * @brief Stream extraction operator for BCDTime
+ *
+ * @param[in] s - the Stream
+ * @param[out] time - the BCD time
+ *
+ * @return Stream&
+ */
+Stream& operator>>(Stream& s, BCDTime& time);
+
+/**
+ * @brief Stream insertion operator for BCDTime
+ *
+ * @param[in/out] s - the Stream
+ * @param[in] time - the BCD time
+ *
+ * @return Stream&
+ */
+Stream& operator<<(Stream& s, BCDTime& time);
+
+} // namespace pels
+} // namespace openpower
diff --git a/extensions/openpower-pels/openpower-pels.mk b/extensions/openpower-pels/openpower-pels.mk
index 1030171..94c7bb8 100644
--- a/extensions/openpower-pels/openpower-pels.mk
+++ b/extensions/openpower-pels/openpower-pels.mk
@@ -1,4 +1,5 @@
 phosphor_log_manager_SOURCES += \
+	extensions/openpower-pels/bcd_time.cpp \
 	extensions/openpower-pels/entry_points.cpp \
 	extensions/openpower-pels/manager.cpp
 
diff --git a/test/openpower-pels/Makefile.include b/test/openpower-pels/Makefile.include
index 295069a..a68b229 100644
--- a/test/openpower-pels/Makefile.include
+++ b/test/openpower-pels/Makefile.include
@@ -2,6 +2,7 @@ TESTS += $(check_PROGRAMS)
 
 check_PROGRAMS += \
 	additional_data_test \
+	bcd_time_test \
 	stream_test
 
 additional_data_test_SOURCES = %reldir%/additional_data_test.cpp
@@ -14,4 +15,13 @@ stream_test_SOURCES = %reldir%/stream_test.cpp
 stream_test_CPPFLAGS = $(test_cppflags)
 stream_test_CXXFLAGS = $(test_cxxflags)
 stream_test_LDADD = $(test_ldadd)
-stream_test_LDFLAGS = $(test_ldflags)
\ No newline at end of file
+stream_test_LDFLAGS = $(test_ldflags)
+
+bcd_time_test_SOURCES = \
+	%reldir%/bcd_time_test.cpp
+bcd_time_test_CPPFLAGS = $(test_cppflags)
+bcd_time_test_CXXFLAGS = $(test_cxxflags)
+bcd_time_test_LDADD = \
+	$(test_ldadd) \
+	$(top_builddir)/extensions/openpower-pels/bcd_time.o
+bcd_time_test_LDFLAGS = $(test_ldflags)
\ No newline at end of file
diff --git a/test/openpower-pels/bcd_time_test.cpp b/test/openpower-pels/bcd_time_test.cpp
new file mode 100644
index 0000000..f1b7663
--- /dev/null
+++ b/test/openpower-pels/bcd_time_test.cpp
@@ -0,0 +1,80 @@
+#include "extensions/openpower-pels/bcd_time.hpp"
+
+#include <gtest/gtest.h>
+
+using namespace openpower::pels;
+
+TEST(BCDTimeTest, ToBCDTest)
+{
+    EXPECT_EQ(toBCD(0), 0x00);
+    EXPECT_EQ(toBCD(1), 0x01);
+    EXPECT_EQ(toBCD(10), 0x10);
+    EXPECT_EQ(toBCD(99), 0x99);
+    EXPECT_EQ(toBCD(37), 0x37);
+    EXPECT_EQ(toBCD(60), 0x60);
+    EXPECT_EQ(toBCD(12345678), 0x12345678);
+    EXPECT_EQ(toBCD(0xF), 0x15);
+}
+
+TEST(BCDTimeTest, FlattenUnflattenTest)
+{
+    std::vector<uint8_t> data{1, 2, 3, 4, 5, 6, 7, 8};
+    Stream stream{data};
+    BCDTime bcd;
+
+    // Unflatten
+    stream >> bcd;
+
+    EXPECT_EQ(bcd.yearMSB, 1);
+    EXPECT_EQ(bcd.yearLSB, 2);
+    EXPECT_EQ(bcd.month, 3);
+    EXPECT_EQ(bcd.day, 4);
+    EXPECT_EQ(bcd.hour, 5);
+    EXPECT_EQ(bcd.minutes, 6);
+    EXPECT_EQ(bcd.seconds, 7);
+    EXPECT_EQ(bcd.hundredths, 8);
+
+    // Flatten
+    uint8_t val = 0x20;
+    bcd.yearMSB = val++;
+    bcd.yearLSB = val++;
+    bcd.month = val++;
+    bcd.day = val++;
+    bcd.hour = val++;
+    bcd.minutes = val++;
+    bcd.seconds = val++;
+    bcd.hundredths = val++;
+
+    stream.offset(0);
+    stream << bcd;
+
+    for (size_t i = 0; i < 8; i++)
+    {
+        EXPECT_EQ(data[i], 0x20 + i);
+    }
+}
+
+TEST(BCDTimeTest, ConvertTest)
+{
+    // Convert a time_point into BCDTime
+    tm time_tm;
+    time_tm.tm_year = 125;
+    time_tm.tm_mon = 11;
+    time_tm.tm_mday = 31;
+    time_tm.tm_hour = 15;
+    time_tm.tm_min = 23;
+    time_tm.tm_sec = 42;
+    time_tm.tm_isdst = 0;
+
+    auto timepoint = std::chrono::system_clock::from_time_t(mktime(&time_tm));
+    auto timeInBCD = getBCDTime(timepoint);
+
+    EXPECT_EQ(timeInBCD.yearMSB, 0x20);
+    EXPECT_EQ(timeInBCD.yearLSB, 0x25);
+    EXPECT_EQ(timeInBCD.month, 0x12);
+    EXPECT_EQ(timeInBCD.day, 0x31);
+    EXPECT_EQ(timeInBCD.hour, 0x15);
+    EXPECT_EQ(timeInBCD.minutes, 0x23);
+    EXPECT_EQ(timeInBCD.seconds, 0x42);
+    EXPECT_EQ(timeInBCD.hundredths, 0x00);
+}