1 files changed, 43 insertions, 0 deletions
diff --git a/user/lib/btoa.c b/user/lib/btoa.c
new file mode 100644
index 0000000..fe5e275
--- /dev/null
+++ b/user/lib/btoa.c
@@ -0,0 +1,43 @@
+#include <stdlib.h>
+
+static char suffixes[] = { 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y', 'R', 'Q' };
+
+char *btoa(size_t bytes, char *buf)
+{
+	// no suffix if under 1K, print up to four digits
+	if (bytes < 1024) {
+		ultoa(bytes, buf, 10);
+		return buf;
+	}
+
+	// store one digit of remainder for decimal
+	unsigned int remainder;
+	// power of 1024
+	int power = 0;
+
+	// iterate until remaining bytes fits in three digits
+	while (bytes >= 1000) {
+		remainder = (bytes % 1024) * 10 / 1024;
+		bytes /= 1024;
+		power += 1;
+	}
+
+	// end of number
+	char *end;
+
+	if (bytes >= 10) {
+		// no decimal
+		end = ultoa(bytes, buf, 10);
+	} else {
+		// decimal
+		end = ultoa(bytes, buf, 10);
+		end[0] = '.';
+		end = ultoa(remainder, end + 1, 10);
+	}
+
+	// add suffix
+	end[0] = suffixes[power - 1];
+	end[1] = '\0';
+
+	return buf;
+}