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/* utf8_support.c - LaTeX to RTF conversion program
This file contains a function used to convert verbatim sections containing
Utf-8 characters properly.
Authors:
2018 Alex Itkes
*/
#include "main.h"
#include "chars.h"
#include "fonts.h"
#include "encodings.h"
/* Initializes a unicode character represented by the Utf-8 sequencd
based on the first byte of the sequence. The returned value must
then be updated with updateUf8Sequence a number of times (returned
by getUtf8SequenceLength using the following bytes of the input
stream.
*/
uint16_t getUtf8SequenceInitialValue (uint8_t byte)
{
if (byte >= 0xF0) {
return byte & ~0xF0;
} else if (byte >= 0xE0) {
return byte & ~0xE0;
} else if (byte >= 0xC0) {
return byte & ~0xC0;
} else {
return 0;
}
}
/* Determines the length of a Utf-8 sequence based on its first byte.
Actually returns the length decreased by 1, i.e. the number of
bytes to be read later.
*/
uint16_t getUtf8SequenceLength (uint8_t byte)
{
if (byte >= 0xF0) {
return 3;
} else if (byte >= 0xE0) {
return 2;
} else if (byte >= 0xC0) {
return 1;
} else {
return 0;
}
}
/* Adds a following byte of Utf-8 sequence to the unicode
character, return the resulting code.
*/
uint16_t updateUtf8Sequence (uint16_t value, uint8_t byte)
{
return ((value << 6) + (byte & ~0xC0));
}
/* Prints a string to RTF with escaped characters if needed.
unlike putRtfStrEscaped it prints Utf8 characters properly.
*/
void putRtfUtf8StrEscaped(const char * string)
{
char *s = (char *) string;
if (string == NULL) return;
while (*s) {
/* Much of code actually copied from Convert () function, but some
code later moved to additional functions (getUtf8SequenceLength,
getUtf8SequenceInitialValue and updateUtf8Sequence).
TODO: Could it be a good idea to call them also from Convert?
*/
if ((uint8_t)(*s) >= 0x80 && (CurrentFontEncoding() == ENCODING_UTF8) && *(s + 1)) {
/* Handle a Utf-8 byte sequence. Try to convert it to a Unicode
character in same way with the Convert function does and then
output it with CmdUnicodeChar.
*/
uint8_t byte = *s;
uint16_t len = getUtf8SequenceLength (byte);
uint16_t value = getUtf8SequenceInitialValue (byte);
uint16_t i;
s++;
for (i=0; i<len; i++) {
if (*s) {
value = updateUtf8Sequence (value, *s);
s++;
} else {
/* If the sequnce is shorted then it should be, display warning and output nothing. */
diagnostics(1, "An incorrect Utf-8 sequence encountered at end of string '%s', continuing anyway...", string);
return;
}
}
diagnostics(4,"(flag = 0x%X) char value = 0X%04X or %u (%u bytes)", (unsigned char) byte, value, value, len);
CmdUnicodeChar(value);
} else {
/* Not a Utf8 character. */
putRtfCharEscaped(*s++);
}
}
}
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