#!/bin/bash
#.Y / 70 83 / / / / 105 / / / /	 / /	      ;A4_QUER.Y
#.YT 3 2 0 0 3 3 1 / / /
#.H!a!0:linux/<scripts>/math/THIS!0.!c
#
# copyright : (C) 2009 by Thomas Bruecker =: tbrue
# email     : public0x05bf@bluewin.ch
#
# tbrue 12jun2006
#
# math THIS : math utilities
#+++++++++++++++++++++++++++
#
# MyHash("linux/<scripts>/math/THIS") = 0x0921
#
# * for every function:
#   * if returned result is not commented, the function returns 0 on no-error.
#

# temp:
  SCRIPTS=root/bin

  . /$SCRIPTS/io/tape_/md5sumS

mathCalc()
  # * $* : expression
  # print result to stdout;
  # * returns
  #   0 if ok,
  {
    local I
    
    let "I = $*";
    echo "$* = $I"
  }


# mathMD5BlockSums()
  # * input: stdin; output: stdout .
#  {
    
#  }

mathToUnit()
  # * convert $3 (in bytes) to unit; print result to stdout;
  # * returns
  #   0 if ok,
  #   1 if wrong parameter for $1,
  #   2 if wrong parameter for $2.
  # * $1 in { b,... } : unit; $2 in { D, U }, D: round down, U: round up;
  #   $3: #bytes.
  {
    local Divisor0x0921 Result0x0921 Round0x0921
 
    case "$2" in
        D)
            Round0x0921=0
          ;;
        U)
            Round0x0921=1
          ;;
        *)
	          return 1
      esac

    case "$1" in
        b)
            Divisor0x0921=1
          ;;
        K)
            Divisor0x0921=1024                      # in 1024 byte units.
          ;;
        kB)
            Divisor0x0921=1000                      # in 1000 byte units.
	        ;;
        M)
	          let "Divisor0x0921 = 1024 * 1024"       # in 1024 * 1024 byte units.
          ;;
        MB)
	          Divisor0x0921=1000000                   # in 1,000,000 byte units.
          ;;
        *)
            return 2
      esac
	
    # * rounding down: Round0x0921 = 0; 
    # * rounding up:   Round0x0921 = Divisor0x0921 - 1 . 
      let "Round0x0921 = Round0x0921 * (Divisor0x0921 - 1)"
    # rounding up:   ( 1 + (Divisor0x0921 - 1) ) = Divisor0x0921 .
      let "Result0x0921 = ($3 + Round0x0921) / Divisor0x0921"
    echo $Result0x0921
    return
  }


math_toUnitError()
  # print "Usage: $1 $2 ... $n\n ..." as an error-message to stdout. 
  # * $1 : name of program concerned by the error,
  # * if $i; i in {2,... ,n} is an empty string, $i is replaced by "UNIT" .
  {
    local I0x0921

    # echo usage:
      echo -n "Usage: $1 "
      
      for (( I0x0921 = $# - 1; I0x0921--; ))
          do
            shift 1
            if [ -z $1 ]; then
                echo -n "UNIT "
              else   
                echo -n "$1 "
              fi
        done

      echo ";"
    
    echo "  UNIT in {\"b\", \"K\", \"kB\", \"M\", \"MB\"} :" 
    echo "    b:                               bytes,"
    echo "    K:                    1,024 byte units,"
    echo "    kB:                   1,000 byte units,"
    echo "    M:  1024 * 1024 = 1,048,576 byte units,"
    echo "    MB:               1,000,000 byte units."

    return 0
  }