printf_helpers.h

/*
 * Copyright (C) 2025 Kernkonzept GmbH.
 * Author(s): Frank Mehnert <frank.mehnert@kernkonzept.com>
 *
 * License: see LICENSE.spdx (in this directory or the directories above)
 */
 
#pragma once
 
#include <stddef.h>
#include <stdio.h>
#include <l4/sys/compiler.h>

L4_INLINE int l4util_human_readable_size(char *outstr, size_t outsize,
                                         unsigned long long bytes)
{
  static char const *const unitstr = "BKMGT";
 
  int idx = sizeof(unitstr) - 2;
  int order;
 
  for (order = idx * 10; order > 10; order -= 10, --idx)
    if (bytes > (1ULL << order))
      break;
 
  unsigned long long value = bytes >> order;
  unsigned long long fract = (bytes - (value << order))
                             / ((1ULL << order) / 10 + 1);
 
  return snprintf(outstr, outsize, "%llu.%1llu %ciB",
                  value, fract, unitstr[idx]);
}