Re: Simple string conversion from UCS2 to ISO8859-1

Il 22/02/2025 14:18, David Brown ha scritto:

On 21/02/2025 20:45, Keith Thompson wrote:

pozz <pozzugno@gmail.com> writes:

I want to write a simple function that converts UCS2 string into ISO8859-1:
>
void ucs2_to_iso8859p1(char *ucs2, size_t size);
>
ucs2 is a string of type "00480065006C006C006F" for "Hello". I'm
passing size because ucs2 isn't null terminated.

>
Is the UCS-2 really represented as a sequence of ASCII hex digits?
>
In actual UCS-2, each character is 2 bytes.  The representation for
"Hello" would be 10 bytes, either "\0H\0e\0l\0l\0o" or
"H\0e\0l\0l\0o\0", depending on endianness.  (UCS-2 is a subset of
UTF-16; the latter uses longer sequences to represent characters
outside the Basic Multilingual Plane.)
>

 My understanding here is that the OP is getting the UCS-2 encoded string in from a modem, almost certainly on a serial line.  The UCS-2 encoded data is itself a binary sequence of 16-bit code units, and the modem firmware is sending those as four hex digits.  This is a very common way to handle transmission of binary data in such systems - there is no need for escapes or other complications to delimit the binary data.  I would expect that the entire incoming message will be comma-separated fields with the time and date, sender's telephone number, and so on, as well as the text itself as this long hex string.
 

Exactly. This is the reply to AT+CMGR command that is standardized in 3GPP TS 27.005.