---

Manual Reference Pages  - maskr (3fortran)

---

NAME

MASKR(3) - [BIT:SET] Generates a right-justified mask

SYNOPSIS

result = maskr( i [,kind] )

         elemental integer(kind=KIND) function maskr(i,KIND)

          integer(kind=**),intent(in) :: i
          integer(kind=**),intent(in),optional :: KIND

CHARACTERISTICS

o	a kind designated as ** may be any supported kind for the type
o	I is an integer
o	KIND Shall be a scalar constant expression of type integer whose value is a supported integer kind.
o	The result is an integer of the same kind as I unless KIND is present, which is then used to specify the kind of the result.

DESCRIPTION

MASKR(3) generates an integer with its rightmost I bits set to 1, and the remaining bits set to 0.

OPTIONS

o	I : the number of right-most bits to set in the integer result. It must be from 0 to the number of bits for the kind of the result. The default kind of the result is the same as I unless the result size is specified by KIND. That is, these Fortran statements must be [char46]true. :

       i >= 0 .and. i <= bitsize(i)      ! if KIND is not specified
       i >= 0 .and. i <= bitsize(0_KIND) ! if KIND is specified

o	KIND : designates the kind of the integer result.

RESULT

The rightmost I bits of the output integer are set to 1 and the other bits are set to 0.

EXAMPLES

Sample program:

    program demo_maskr
    implicit none
    integer :: i

      ! basics
       print *,’basics’
       write(*,’(i0,t5,b32.32)’) 1, maskr(1)
       write(*,’(i0,t5,b32.32)’) 5,  maskr(5)
       write(*,’(i0,t5,b32.32)’) 11, maskr(11)
       print *,"should be equivalent on two’s-complement processors"
       write(*,’(i0,t5,b32.32)’) 1,  shiftr(-1,bit_size(0)-1)
       write(*,’(i0,t5,b32.32)’) 5,  shiftr(-1,bit_size(0)-5)
       write(*,’(i0,t5,b32.32)’) 11, shiftr(-1,bit_size(0)-11)

      ! elemental
       print *,’elemental ’
       print *,’(array argument accepted like called with each element)’
       write(*,’(*(i11,1x,b0.32,1x,/))’) maskr([(i,i,i=0,bit_size(0),1)])

    end program demo_maskr

Results:

     >   basics
     basics
     > 1   00000000000000000000000000000001
     > 5   00000000000000000000000000011111
     > 11  00000000000000000000011111111111
     >  should be equivalent on two’s-complement processors
     > 1   00000000000000000000000000000001
     > 5   00000000000000000000000000011111
     > 11  00000000000000000000011111111111
     >  elemental
     >  (array argument accepted like called with each element)
     >           0 00000000000000000000000000000000
     >           1 00000000000000000000000000000001
     >           3 00000000000000000000000000000011
     >           7 00000000000000000000000000000111
     >          15 00000000000000000000000000001111
     >          31 00000000000000000000000000011111
     >          63 00000000000000000000000000111111
     >         127 00000000000000000000000001111111
     >         255 00000000000000000000000011111111
     >         511 00000000000000000000000111111111
     >        1023 00000000000000000000001111111111
     >        2047 00000000000000000000011111111111
     >        4095 00000000000000000000111111111111
     >        8191 00000000000000000001111111111111
     >       16383 00000000000000000011111111111111
     >       32767 00000000000000000111111111111111
     >       65535 00000000000000001111111111111111
     >      131071 00000000000000011111111111111111
     >      262143 00000000000000111111111111111111
     >      524287 00000000000001111111111111111111
     >     1048575 00000000000011111111111111111111
     >     2097151 00000000000111111111111111111111
     >     4194303 00000000001111111111111111111111
     >     8388607 00000000011111111111111111111111
     >    16777215 00000000111111111111111111111111
     >    33554431 00000001111111111111111111111111
     >    67108863 00000011111111111111111111111111
     >   134217727 00000111111111111111111111111111
     >   268435455 00001111111111111111111111111111
     >   536870911 00011111111111111111111111111111
     >  1073741823 00111111111111111111111111111111
     >  2147483647 01111111111111111111111111111111
     >          -1 11111111111111111111111111111111

STANDARD

Fortran 2008

SEE ALSO

MASKL(3)

Fortran intrinsic descriptions (license: MIT) @urbanjost

---