Byte encodings and checksums

TOBASE64, FROMBASE64, TOHEX, FROMHEX, CRC16 and CRC32 turn bytes into text and back and compute checksums, usually together with the encryption and hash functions. They only build values, so they work in every script. All of them need TapHome Next 2026.1.40991+.

TOBASE64, TOHEX, CRC16 and CRC32 take byte data like the encryption functions: a collection<uint8>, a blob or a string, used as ISO-8859-1 bytes (for UTF-8 pass TOBYTES(text, "utf-8")). TOBASE64 and TOHEX return a string, CRC16 and CRC32 a uint number; FROMBASE64 and FROMHEX take text and return a collection<uint8>.

TOBASE64, FROMBASE64#

TOBASE64 turns byte data into Base64 text, FROMBASE64 turns Base64 text back into bytes.

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TOBASE64(data [, variant])
FROMBASE64(text [, variant])

variant is "standard" (the default) or "url", not case sensitive. "url" is base64url (RFC 4648 §5), which uses - and _ instead of + and /. TOBASE64 with "url" leaves out the = padding, as JWT and most web APIs expect (Python base64.urlsafe_b64encode(data).rstrip(b"=")); FROMBASE64 with "url" accepts text with or without the padding.

Returns — TOBASE64 a string, FROMBASE64 a collection<uint8>.

Remarks — ENCODE and DECODE with "base64" go through UTF-8 text, so bytes above 0x7F do not survive them. Encrypted and other binary data goes through TOBASE64 and FROMBASE64.

Example

# standard Base64 of two bytes
TOBASE64(FROMHEX("fbff"));
# Result: "+/8="
# base64url: no padding, - and _ instead of + and /
TOBASE64(FROMHEX("fbff"), "url");
# Result: "-_8"
# decode base64url back to hex text
TOHEX(FROMBASE64("-_8", "url"));
# Result: "fbff"

Errors — TOBASE64 Unknown variant. Valid values are ‘standard’, ‘url’ (FROMBASE64 names itself); FROMBASE64 - ‘+’ and ‘/’ are not base64url characters, leave the “url” argument out for standard Base64; FROMBASE64 - argument must be a string; The provided text does not have the base64 format.

Available — TapHome Next 2026.1.40991+.

TOHEX, FROMHEX#

TOHEX returns byte data as lower-case hexadecimal text, FROMHEX turns hexadecimal text back into bytes.

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TOHEX(data)
FROMHEX(text)

Remarks

• FROMHEX accepts upper- and lower-case digits and whitespace between them, as Python’s bytes.fromhex. Any other character, including a 0x prefix or : separators, is an error, and so is an odd number of digits. An empty string gives an empty collection.
• Unlike BYTECOLLECTION from hexadecimal text, which silently ignores other characters and is limited to 2048 bytes, FROMHEX has no length limit, so it takes back anything TOHEX produced.

Example

# three bytes as Base64
TOBASE64(FROMHEX("ff0080"));
# Result: "/wCA"
# Base64 back to bytes, then hex text
TOHEX(FROMBASE64("/wCA"));
# Result: "ff0080"
# upper case and spaces are accepted
TOHEX(FROMHEX("FF 00 80"));
# Result: "ff0080"

Errors — FROMHEX - invalid hex digit ‘x’ (remove a prefix or separators with REPLACE); FROMHEX - the number of hex digits must be even, it is N; FROMHEX - argument must be a string.

Available — TapHome Next 2026.1.40991+.

CRC16, CRC32#

CRC16 returns the 16-bit CRC checksum of byte data, CRC32 the CRC-32 of zlib, Ethernet and ZIP (Python zlib.crc32).

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CRC16(data [, variant])
CRC32(data)

variant selects the parameters of CRC16, not case sensitive. The check value is the CRC of the text "123456789":

The check value of CRC32 is 0xCBF43926 (3421780262).

Returns — a uint number, not bytes. To put the checksum into a frame, pack it with PACKVALUE in the byte order the protocol expects; Modbus RTU sends the low byte first.

Example

TOSTRING(CRC16(FROMHEX("0103000A0001")), "X4");
# Result: "08A4"
TOSTRING(CRC32("123456789"), "X8");
# Result: "CBF43926"

Example — append a Modbus RTU checksum

# frame bytes from hex text
VAR frame := FROMHEX("01 03 00 0A 00 01");
# empty buffer of 2 bytes for the checksum
VAR crc := BYTECOLLECTION(2);
# pack the CRC16 low byte first
PACKVALUE(crc, 0, LittleEndianUint16, CRC16(frame));
# append the checksum to the frame
APPEND(frame, crc);
# Result: frame is 01 03 00 0A 00 01 A4 08

Errors — CRC16 Unknown variant. Valid values are ‘MODBUS’, ‘XMODEM’, ‘CCITT-FALSE’, ‘KERMIT’.

Available — TapHome Next 2026.1.40991+.

See also — Encryption and hashes, Binary data, Data type conversions.