Manual Reference Pages - trailz (3fortran)
TRAILZ(3) - [BIT:COUNT] Number of trailing zero bits of an integer
SYNOPSIS
result = trailz(i)
elemental integer function trailz(i)integer(kind=**),intent(in) :: i
CHARACTERISTICS
o I is an integer of any kind. o the result is an integer of default kind
DESCRIPTION
TRAILZ(3) returns the number of trailing zero bits of an integer value.
OPTIONS
o I : the value to count trailing zero bits in
RESULT
The number of trailing rightmost zero bits in an integer value after the last non-zero bit.
> right-most non-zero bit > V > |0|0|0|1|1|1|0|1|0|0|0|0|0|0| > ^ |___________| trailing zero bits > bit_size(i)If all the bits of I are zero, the result is the size of the input value in bits, ie. BIT_SIZE(I).
The result may also be seen as the position of the rightmost 1 bit in I, starting with the rightmost bit being zero and counting to the left.
EXAMPLES
Sample program:
program demo_trailzResults:! some common integer kinds use, intrinsic :: iso_fortran_env, only : & & integer_kinds, int8, int16, int32, int64
implicit none
! a handy format character(len=*),parameter :: & & show = ’(1x,"value=",i4,", value(bits)=",b32.32,1x,", trailz=",i3)’
integer(kind=int64) :: bigi ! basics write(*,*)’Note default integer is’,bit_size(0),’bits’ print show, -1, -1, trailz(-1) print show, 0, 0, trailz(0) print show, 1, 1, trailz(1) print show, 96, 96, trailz(96) ! elemental print *, ’elemental and any integer kind:’ bigi=2**5 write(*,*) trailz( [ bigi, bigi*256, bigi/2 ] ) write(*,’(1x,b64.64)’)[ bigi, bigi*256, bigi/2 ]
end program demo_trailz
> Note default integer is 32 bits > value= -1, value(bits)=11111111111111111111111111111111 , trailz= 0 > value= 0, value(bits)=00000000000000000000000000000000 , trailz= 32 > value= 1, value(bits)=00000000000000000000000000000001 , trailz= 0 > value= 96, value(bits)=00000000000000000000000001100000 , trailz= 5 > elemental and any integer kind: > 5 13 4 > 0000000000000000000000000000000000000000000000000000000000100000 > 0000000000000000000000000000000000000000000000000010000000000000 > 0000000000000000000000000000000000000000000000000000000000010000
STANDARD
Fortran 2008
SEE ALSO
BIT_SIZE(3), POPCNT(3), POPPAR(3), LEADZ(3)
Fortran intrinsic descriptions (license: MIT) @urbanjost
| Nemo Release 3.1 | trailz (3fortran) | November 02, 2024 |
