-#define TERABYTE (1024ULL * 1024 * 1024 * 1024)
-#define GIGABYTE (1024ULL * 1024 * 1024)
-#define MEGABYTE (1024ULL * 1024)
-#define KILOBYTE (1024ULL)
+#define BINARY_BASE UINT64_C(1024)
+#define DECIMAL_BASE UINT64_C(1000)
+
+#define MAX_EXPONENT 4
+
+static const char * const iec_symbols[MAX_EXPONENT+1] = {"", "Ki", "Mi", "Gi", "Ti"};
+static const char * const si_symbols[MAX_EXPONENT+1] = {"", "k", "M", "G", "T"};
+static const char * const custom_symbols[MAX_EXPONENT+1] = {"", "K", "M", "G", "T"};
+
+/*
+ * Formats bytes according to the given base and set of symbols.
+ *
+ */
+static int format_bytes(char *outwalk, uint64_t bytes, uint64_t base, const char * const symbols[]) {
+ double size = bytes;
+ int exponent = 0;
+ while (size >= base && exponent < MAX_EXPONENT) {
+ size /= base;
+ exponent += 1;
+ }
+ return sprintf(outwalk, "%.1f %sB", size, symbols[exponent]);
+}