[base, thin_ls] factor out disk_units code

base/disk_units.cc

@@ -0,0 +1,72 @@
+#include "base/disk_units.h"
+
+#include <stdexcept>
+#include <boost/lexical_cast.hpp>
+
+using namespace std;
+using namespace boost;
+
+//----------------------------------------------------------------
+
+unsigned long long
+base::disk_unit_multiplier(disk_unit u)
+{
+	switch (u) {
+	case UNIT_BYTE:
+		return 1;
+
+	case UNIT_SECTOR:
+		return 512;
+
+	case UNIT_kB:
+		return 1000;
+
+	case UNIT_MB:
+		return 1000000;
+
+	case UNIT_GB:
+		return 1000000000ull;
+
+	case UNIT_TB:
+		return 1000000000000ull;
+
+	case UNIT_PB:
+		return 1000000000000000ull;
+
+	case UNIT_KiB:
+		return 1024ull;
+
+	case UNIT_MiB:
+		return 1024ull * 1024ull;
+
+	case UNIT_GiB:
+		return 1024ull * 1024ull * 1024ull;
+
+	case UNIT_TiB:
+		return 1024ull * 1024ull * 1024ull * 1024ull;
+
+	case UNIT_PiB:
+		return 1024ull * 1024ull * 1024ull * 1024ull * 1024ull;
+	}
+
+	throw runtime_error("unknown unit type");
+	return 1;
+}
+
+string
+base::format_disk_unit(unsigned long long numerator, disk_unit u)
+{
+	numerator *= disk_unit_multiplier(u);
+	unsigned i;
+	for (i = 0; numerator >= 1024; i++)
+		numerator /= 1024;
+
+	char const *extensions[] = {
+		"", "KiB", "MiB", "GiB", "TiB", "PiB"
+	};
+
+	// FIXME: check subscript of i
+	return lexical_cast<string>(numerator) + " " + extensions[i];
+}
+
+//----------------------------------------------------------------