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),4)])

    end program demo_maskr

Results:

> 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 > 15 00000000000000000000000000001111 > 255 00000000000000000000000011111111 > 4095 00000000000000000000111111111111 > 65535 00000000000000001111111111111111 > 1048575 00000000000011111111111111111111 > 16777215 00000000111111111111111111111111 > 268435455 00001111111111111111111111111111 > -1 11111111111111111111111111111111

STANDARD

Fortran 2008

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.