nim-libp2p/docs/hexdump.nim

#
# Copyright (c) 2016 Eugene Kabanov <ka@hardcore.kiev.ua>
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from strutils import toHex, repeat

proc dumpHex*(pbytes: pointer, nbytes: int, items = 1, ascii = true): string =
  ## Return hexadecimal memory dump representation pointed by ``p``.
  ## ``nbytes`` - number of bytes to show
  ## ``items``  - number of bytes in group (supported ``items`` count is
  ##  1, 2, 4, 8)
  ## ``ascii``  - if ``true`` show ASCII representation of memory dump.
  result = ""
  let hexSize = items * 2
  var i = 0
  var slider = pbytes
  var asciiText = ""
  while i < nbytes:
    if i %% 16 == 0:
      result = result & toHex(cast[BiggestInt](slider), sizeof(BiggestInt) * 2) & ":  "
    var k = 0
    while k < items:
      var ch = cast[ptr char](cast[uint](slider) + k.uint)[]
      if ord(ch) > 31 and ord(ch) < 127:
        asciiText &= ch
      else:
        asciiText &= "."
      inc(k)
    case items
    of 1:
      result = result & toHex(cast[BiggestInt](cast[ptr uint8](slider)[]), hexSize)
    of 2:
      result = result & toHex(cast[BiggestInt](cast[ptr uint16](slider)[]), hexSize)
    of 4:
      result = result & toHex(cast[BiggestInt](cast[ptr uint32](slider)[]), hexSize)
    of 8:
      result = result & toHex(cast[BiggestInt](cast[ptr uint64](slider)[]), hexSize)
    else:
      raise newException(ValueError, "Wrong items size!")
    result = result & " "
    slider = cast[pointer](cast[uint](slider) + items.uint)
    i = i + items
    if i %% 16 == 0:
      result = result & " " & asciiText
      asciiText.setLen(0)
      result = result & "\n"

  if i %% 16 != 0:
    var spacesCount = ((16 - (i %% 16)) div items) * (hexSize + 1) + 1
    result = result & repeat(' ', spacesCount)
    result = result & asciiText
  result = result & "\n"

proc dumpHex*[T](v: openArray[T], items: int = 0, ascii = true): string =
  ## Return hexadecimal memory dump representation of openArray[T] ``v``.
  ## ``items``  - number of bytes in group (supported ``items`` count is
  ##  0, 1, 2, 4, 8). If ``items`` is ``0`` group size will depend on
  ## ``sizeof(T)``.
  ## ``ascii``  - if ``true`` show ASCII representation of memory dump.
  var i = 0
  if items == 0:
    when sizeof(T) == 2:
      i = 2
    elif sizeof(T) == 4:
      i = 4
    elif sizeof(T) == 8:
      i = 8
    else:
      i = 1
  else:
    i = items
  result = dumpHex(unsafeAddr v[0], sizeof(T) * len(v), i, ascii)