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58 lines
1.3 KiB
58 lines
1.3 KiB
//
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// Created by MightyPork on 2017/09/10.
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//
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#include "utf8.h"
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/**
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* Encode a code point using UTF-8
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*
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* @author Ondřej Hruška <ondra@ondrovo.com>
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* @license MIT
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*
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* @param out - output buffer (min 4 characters), will be 0-terminated if shorten than 4
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* @param utf - code point 0-0x10FFFF
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* @return number of bytes on success, 0 on failure (also produces U+FFFD, which uses 3 bytes)
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*/
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int ICACHE_FLASH_ATTR
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utf8_encode(char *out, uint32_t utf)
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{
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if (utf <= 0x7F) {
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// Plain ASCII
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out[0] = (char) utf;
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out[1] = 0;
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return 1;
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}
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else if (utf <= 0x07FF) {
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// 2-byte unicode
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out[0] = (char) (((utf >> 6) & 0x1F) | 0xC0);
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out[1] = (char) (((utf >> 0) & 0x3F) | 0x80);
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out[2] = 0;
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return 2;
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}
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else if (utf <= 0xFFFF) {
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// 3-byte unicode
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out[0] = (char) (((utf >> 12) & 0x0F) | 0xE0);
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out[1] = (char) (((utf >> 6) & 0x3F) | 0x80);
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out[2] = (char) (((utf >> 0) & 0x3F) | 0x80);
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out[3] = 0;
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return 3;
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}
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else if (utf <= 0x10FFFF) {
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// 4-byte unicode
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out[0] = (char) (((utf >> 18) & 0x07) | 0xF0);
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out[1] = (char) (((utf >> 12) & 0x3F) | 0x80);
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out[2] = (char) (((utf >> 6) & 0x3F) | 0x80);
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out[3] = (char) (((utf >> 0) & 0x3F) | 0x80);
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// out[4] = 0;
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return 4;
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}
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else {
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// error - use replacement character
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out[0] = (char) 0xEF;
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out[1] = (char) 0xBF;
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out[2] = (char) 0xBD;
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out[3] = 0;
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return 0;
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}
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}
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