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stdlib: Clean up and export SDL_UCS4ToUTF8().

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Also fix internal usage of the function.

Fixes #10157.
This commit is contained in:
Ryan C. Gordon
2024-07-04 01:09:46 -04:00
parent f338fa20dd
commit c3bf874abf
9 changed files with 74 additions and 33 deletions
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36
src/stdlib/SDL_string.c
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@@ -42,6 +42,42 @@
SDL_COMPILE_TIME_ASSERT(sizeof_wchar_t, sizeof(wchar_t) == SDL_SIZEOF_WCHAR_T);
char *SDL_UCS4ToUTF8(Uint32 codepoint, char *dst)
{
if (!dst) {
return NULL; // I guess...?
} else if (codepoint > 0x10FFFF) { // Outside the range of Unicode codepoints (also, larger than can be encoded in 4 bytes of UTF-8!).
codepoint = SDL_INVALID_UNICODE_CODEPOINT;
} else if ((codepoint >= 0xD800) && (codepoint <= 0xDFFF)) { // UTF-16 surrogate values are illegal in UTF-8.
codepoint = SDL_INVALID_UNICODE_CODEPOINT;
}
Uint8 *p = (Uint8 *)dst;
if (codepoint <= 0x7F) {
*p = (Uint8)codepoint;
++dst;
} else if (codepoint <= 0x7FF) {
p[0] = 0xC0 | (Uint8)((codepoint >> 6) & 0x1F);
p[1] = 0x80 | (Uint8)(codepoint & 0x3F);
dst += 2;
} else if (codepoint <= 0xFFFF) {
p[0] = 0xE0 | (Uint8)((codepoint >> 12) & 0x0F);
p[1] = 0x80 | (Uint8)((codepoint >> 6) & 0x3F);
p[2] = 0x80 | (Uint8)(codepoint & 0x3F);
dst += 3;
} else {
SDL_assert(codepoint <= 0x10FFFF);
p[0] = 0xF0 | (Uint8)((codepoint >> 18) & 0x07);
p[1] = 0x80 | (Uint8)((codepoint >> 12) & 0x3F);
p[2] = 0x80 | (Uint8)((codepoint >> 6) & 0x3F);
p[3] = 0x80 | (Uint8)(codepoint & 0x3F);
dst += 4;
}
return dst;
}
// this expects `from` and `to` to be UTF-32 encoding!
int SDL_CaseFoldUnicode(const Uint32 from, Uint32 *to)
{