[TF] mylib.tf : updated chr2chr()

[tinyfugue at attbi.c. (Galvin)]

I made the code more tigher, it works slightly faster than the old chr2chr()

;==============================================================================
; chr2chr()
;
; Changes one character to difference character in a string
; USAGE:
; x := chr2chr("string", "searchchar", "changechar")
;
; x           : contains "string" with all "." as "_".
; "string"    : any string.
; "searchar"  : The character to be changed in "string".
; "changechar : The character to replace each occrance of "searchar" in
;               "string".
;==============================================================================
/def chr2chr = \
  /let right_ 0 %;\
  /test right_ := {1} %;\
  /let searchchar_ 0 %;\
  /test searchchar_ := {2} %;\
  /let changechar_ 0 %;\
  /test changechar_ := {3} %;\
  /let left_= %;\
  /let pos_ -1 %;\
  /WHILE ( (pos_ := strstr(right_, searchchar_)) > -1) \
    /test left_  := strcat(left_, substr(right_, 0, pos_), changechar_) %;\
    /test right_ := substr(right_, pos_ + 1) %;\
  /DONE %;\
  /RETURN strcat(left_, right_)