faster to_lower and to_upper

[jalvesz]

Following discussion here #703

[jvdp1]

Why did you not modify char_to_lower instead of each occurence?

[jvdp1]

What are the origin of these numbers?

[urbanjost]

I would prefer something like

integer, parameter :: la=iachar('A'), lz=iachar('Z')

as 65 is the ADE (ASCII Decimal Equivalent) of capital "A", and 90 is the ADE for capital Z". The advantage of numbers is that they are case-insensitive; but in this case I think the letters are much clearer. Longer descriptive names for the variables would be nice as well IMHO.

DECIMAL
*-------*-------*-------*-------*-------*-------*-------*-------*
| 00 nul| 01 soh| 02 stx| 03 etx| 04 eot| 05 enq| 06 ack| 07 bel|
| 08 bs | 09 ht | 10 nl | 11 vt | 12 np | 13 cr | 14 so | 15 si |
| 16 dle| 17 dc1| 18 dc2| 19 dc3| 20 dc4| 21 nak| 22 syn| 23 etb|
| 24 can| 25 em | 26 sub| 27 esc| 28 fs | 29 gs | 30 rs | 31 us |
| 32 sp | 33  ! | 34  " | 35  # | 36  $ | 37  % | 38  & | 39  ' |
| 40  ( | 41  ) | 42  * | 43  + | 44  , | 45  - | 46  . | 47  / |
| 48  0 | 49  1 | 50  2 | 51  3 | 52  4 | 53  5 | 54  6 | 55  7 |
| 56  8 | 57  9 | 58  : | 59  ; | 60  < | 61  = | 62  > | 63  ? |
| 64  @ | 65  A | 66  B | 67  C | 68  D | 69  E | 70  F | 71  G |
| 72  H | 73  I | 74  J | 75  K | 76  L | 77  M | 78  N | 79  O |
| 80  P | 81  Q | 82  R | 83  S | 84  T | 85  U | 86  V | 87  W |
| 88  X | 89  Y | 90  Z | 91  [ | 92  \ | 93  ] | 94  ^ | 95  _ |
| 96  ` | 97  a | 98  b | 99  c |100  d |101  e |102  f |103  g |
|104  h |105  i |106  j |107  k |108  l |109  m |110  n |111  o |
|112  p |113  q |114  r |115  s |116  t |117  u |118  v |119  w |
|120  x |121  y |122  z |123  { |124  | |125  } |126  ~ |127 del|
*-------*-------*-------*-------*-------*-------*-------*-------*

[jvdp1]

Maybe we could do the same for wp:

Suggested change

	integer, parameter :: wp= 32, BA=iachar('A'), BZ=iachar('Z')
	integer, parameter :: wp= iachar('A')-iachar('a'), BA=iachar('A'), BZ=iachar('Z')

Or is it not correct?

[jvdp1]

LGTM. Thank you @jalvesz for this improvement.

[jvdp1]

I'll merge this PR. Thank you @jalvesz for these changes.