Base64 Encoding/Decoding ============================================ Robert Dickow <> Package base64 Version 1.0.0 - 2018-03-30 ### Description: A simple lexicon to encode and decode strings or arbitrary data in base64 format using most common (e.g. MIME) character mapping and padding characters. ### Top level words: \ N.B. For flexibility, the buffers are not delimited. Store your own counts as needed. \ Given an output buffer, a source buffer holding un-encoded data, and its length \ in bytes, returns addr of the output buffer holding encoded data and its length. `>BASE64` ( c-addr-output c-addr-source-data n-len -- c-addr-output n-len ) \ Given an output buffer, a source buffer holding encoded data, and its length \ in bytes, returns address of the decoded output buffer and its length. `BASE64>` ( c-addr-output c-addr-source-data n-len -- c-addr-output n-len ) ### Helper words: \ given buffer and its length, returns bytes needed for encoded data. `BASE64-ENCODE-LEN` ( n-decoded-len -- n ) \ given buffer addr and its length, returns bytes needed for decoded data. `BASE64-DECODE-LEN` ( c-addr-encoded n-len -- n ) \ given buffer addr and its length, returns buffer addr and new length \ trimming the count of padding characters, if present. The buffer is not \ touched. `TRIM-PADDING` ( c-addr-encoded n -- c-addr-encoded n ) ### Configuration words: `PADDING?` variable, TRUE|FALSE to use padding or not. `PADDING-CHR` variable, defaulted to the usual '=' ### Include file base64.f ### Dependencies none ### Usage Example \ ************************* \ Set up a buffer in heap memory based \ on the storage needs of a string of \ text to encode. \ ************************* \ for storing the address of allocated memory: VARIABLE output-buffer \ the string to encode and later decode: S" Hello World!!" DUP ( c-addr len len ) \ allocate len bytes, drop the Ior, and save address: ALLOCATE DROP DUP output-buffer ! ( c-addr len c-addr-output ) \ set up the stack for encoding word: ROT ROT ( c-addr-output c-addr len ) \ ********************* \ Encode: \ ********************* >BASE64 ( c-addr-output n-len ) 2DUP CR TYPE ( c-addr-output n-len ) \ displays: "SGVsbG8gV29ybGQhIQ==" \ ********************* \ Decode: \ ********************* \ Note: PAD works fine for small buffers. \ The same buffer won't work for both output and \ input in the same operation, hence the allocated \ memory buffer. PAD ROT ROT ( addr-pad c-addr-output n-len ) BASE64> CR ( -- addr-pad n-len ) TYPE \ displays: "Hello World!!" output-buffer @ FREE DROP ( -- ) \ done ## Tests DECIMAL \ set up oversized buffers for the encoded and decoded data: CREATE EncodedOutput-Buffer 50 ALLOT CREATE DecodedOutput-Buffer 50 ALLOT T{ EncodedOutput-Buffer S" Man is distinguished" >BASE64 S" TWFuIGlzIGRpc3Rpbmd1aXNoZWQ=" COMPARE -> 0 }T T{ DecodedOutput-Buffer S" TWFuIGlzIGRpc3Rpbmd1aXNoZWQ=" BASE64> S" Man is distinguished" COMPARE -> 0 }T T{ S" Hello world!" 2DUP EncodedOutput-Buffer -ROT >BASE64 DecodedOutput-Buffer -ROT BASE64> COMPARE -> 0 }T ## Changes 1.0.0 first version ## Bug Reports Please send suggestions, comments, or bug reports Bob Dickow <> ## Compatibility This lexicon was tested on SwiftForth 3.7.1