From 5e158e37a5e37f8821eef330a3c9bc118efde0f8 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 20 Sep 2018 16:39:27 -0700
Subject: [PATCH] ircd: Add pretty IEC unit printing utils.

---
 include/ircd/lex_cast.h |  3 +++
 ircd/lexical.cc         | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/ircd/lex_cast.h b/include/ircd/lex_cast.h
index c2a36092c..a92a44215 100644
--- a/include/ircd/lex_cast.h
+++ b/include/ircd/lex_cast.h
@@ -36,6 +36,9 @@ namespace ircd
 	const_buffer a2u(const mutable_buffer &out, const const_buffer &in);
 	string_view u2a(const mutable_buffer &out, const const_buffer &in);
 	std::string u2a(const const_buffer &in);
+
+	string_view pretty_iec_unit(const mutable_buffer &out, const uint64_t &value);
+	std::string pretty_iec_unit(const uint64_t &value);
 }
 
 namespace ircd
diff --git a/ircd/lexical.cc b/ircd/lexical.cc
index 42bcc65ec..65da4c74a 100644
--- a/ircd/lexical.cc
+++ b/ircd/lexical.cc
@@ -22,6 +22,42 @@
 // misc util
 //
 
+std::string
+ircd::pretty_iec_unit(const uint64_t &value)
+{
+	return util::string(32, [&value]
+	(const mutable_buffer &out)
+	{
+		return pretty_iec_unit(out, value);
+	});
+}
+
+ircd::string_view
+ircd::pretty_iec_unit(const mutable_buffer &out,
+                      const uint64_t &value)
+try
+{
+	auto pos(0);
+	auto v(value);
+	for(; v > 1024; v /= 1024, ++pos);
+	static const std::array<string_view, 7>  unit
+	{
+		"B", " KiB", "MiB", "GiB", "TiB", "PiB", "EiB"
+	};
+
+	return fmt::sprintf
+	{
+		out, "%lu %s", v, unit.at(pos)
+	};
+}
+catch(const std::out_of_range &e)
+{
+	return fmt::sprintf
+	{
+		out, "%lu B", value
+	};
+}
+
 std::string
 ircd::u2a(const const_buffer &in)
 {