uint8_t **dst_ptr) {

// hex_to_u32_nocheck fills high 16 bits of the return value with 1s if the

// conversion isn't valid; we defer the check for this to inside the

// multilingual plane check

uint32_t code_point = hex_to_u32_nocheck(*src_ptr + 2);

*src_ptr += 6;

// check for low surrogate for characters outside the Basic

// Multilingual Plane.

if (code_point >= 0xd800 && code_point < 0xdc00) {

if (((*src_ptr)[0] != '\\') || (*src_ptr)[1] != 'u') {

return false;

}

uint32_t code_point_2 = hex_to_u32_nocheck(*src_ptr + 2);

// if the first code point is invalid we will get here, as we will go past

// the check for being outside the Basic Multilingual plane. If we don't

// find a \u immediately afterwards we fail out anyhow, but if we do,

// this check catches both the case of the first code point being invalid

// or the second code point being invalid.

if ((code_point | code_point_2) >> 16) {

return false;

}

code_point =

(((code_point - 0xd800) << 10) | (code_point_2 - 0xdc00)) + 0x10000;

*src_ptr += 6;

}

size_t offset = codepoint_to_utf8(code_point, *dst_ptr);

*dst_ptr += offset;

return offset > 0;