Usage

Setup

Import the main module and initialise the library once before any encode/decode call:

use befor64

call b64_init()

The module-level flag is_b64_initialized can be queried at any time:

if (.not. is_b64_initialized) call b64_init()

Encoding

All encode calls return an allocatable character string (character(len=:), allocatable). The compiler must support this Fortran 2003 feature.

Scalar real

character(len=:), allocatable :: code

call b64_encode(n=12._R8P, code=code)
print '(A)', code   ! AAAAAAAA8D8=

Integer array

character(len=:), allocatable :: code

call b64_encode(n=[12_I4P, 1_I4P], code=code)
print '(A)', code

Character scalar

character(len=:), allocatable :: code

call b64_encode(n='hello', code=code)

Unlimited polymorphic

class(*), allocatable :: val
character(len=:), allocatable :: code

allocate(val, source=3.14_R8P)
call b64_encode_up(n=val, code=code)

Decoding

You must know the type of the encoded data ahead of time.

Scalar real

real(R8P) :: decoded

call b64_decode(code='AAAAAAAA8D8=', n=decoded)

Integer array

integer(I8P) :: decoded(1:4)

call b64_decode(code='FwAAAAAAAABEAQAAAAAAABBwhAEAAAAAAgAAAAAAAAA=', n=decoded)

Unlimited polymorphic

class(*), allocatable :: val

allocate(real(R8P) :: val)
call b64_decode_up(code=code, n=val)

Encoding Heterogeneous Data

To encode two arrays of different kinds together, first pack them with pack_data, then pass the resulting byte array to b64_encode:

real(R8P)               :: a(1:12)
real(R4P)               :: b(-1:5)
integer(I1P), allocatable :: packed(:)
character(len=:), allocatable :: code

call pack_data(a1=a, a2=b, packed=packed)
call b64_encode(n=packed, code=code)

Supported array combinations for pack_data:

a1 kind	a2 kind
real(R8P)	real(R4P), integer(I8P/I4P/I2P/I1P)
real(R4P)	real(R8P), integer(I8P/I4P/I2P/I1P)
integer(any)	real(any), integer(any)

For heterogeneous scalar packing and character mixing, see the Features page — those are not yet implemented.

Module Summary

Symbol	Description
b64_init	Initialise the library (required before first use)
is_b64_initialized	Logical flag — true after b64_init
b64_encode	Encode any intrinsic type to a Base64 string
b64_encode_up	Encode unlimited polymorphic variable
b64_decode	Decode a Base64 string to an intrinsic type
b64_decode_up	Decode to unlimited polymorphic variable
pack_data	Pack two numeric arrays of different kinds into I1P bytes