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9511 :: Reworking "c things" like static const unsigned char clcidx[19] =

• catswhiskers (orginal) [2022-10-07T14:25:38+02:00] view original

  Why does this work?:

  var
        tab: array[ 19, uint16]
  for i, v in [ 16.uint16, 17, 18, 0,  8, 7,  9, 6, 10, 5, 11,  4, 12, 3, 13, 2, 14, 1, 15]:
     tab[ i] = v
  Run

  but not for

  var
       tab: array[ 16, uint32]
  for i, v in [ 0x00000000.uint32, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4, 0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C, 0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C]
     tab[ i] = v
  Run

  which always fails with

  Error: type mismatch: got ‘int64' for ‘0x00000000EDB88320‘i64' but expected ‘uint32‘

  So that I have to go round the houses with this

  var
      tab: array[ 16, uint32]
      i: int
  for v in """0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC,
                      0x76DC4190, 0x6B6B51F4, 0x4DB26158, 0x5005713C, 0xEDB88320,
                      0xF00F9344, 0xD6D6A3E8, 0xCB61B38C, 0x9B64C2B0, 0x86D3D2D4,
                      0xA00AE278, 0xBDBDF21C""".split ", ":
     let s    = v.strip
     tab[ i] = s.parseHexInt.uint32
     inc i
  Run

  which is ok ish but irritating?

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• Araq (orginal) [2022-10-07T15:12:41+02:00] view original

  Read the manual.

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• DeletedUser (orginal) [2022-10-07T16:10:13+02:00] view original

  I don't know why the hex literals above high(int32) are locked into int64 but you do not have to parse hex strings here, you can just use an array of int64:

  var tab: array[16, uint32]
  for i, v in [0x00000000.int64, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4, 0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C, 0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C]:
    tab[i] = v.uint32
  Run

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• catswhiskers (orginal) [2022-10-07T16:26:10+02:00] view original

  Thanks Hlaaftana. That's really why I asked the question: old and addled brains need that kind of leg up, because despite Araq's impatient answer I have read the manual many times over very many years. Unfortunately old and addled brains suffer from bit rot. It is interesting the patience shown toward newcomers, but not to those at the more senile end of the range such as myself. Thanks again.

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