zap/source/any/str/utf8dec.c


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/*
	Copyright 2022-2023 Gabriel Jensen.
	This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
	If a copy of the MPL was not distributed with this file, You can obtain one at <https://mozilla.org/MPL/2.0>.
*/

#include <zap/str.h>

void zap_utf8dec(zap_i02 * dest,zap_i8 const * src) {
	for (;;++dest) {
		zap_i8 const oct = *src;
		if (oct == 0x0u) break;
		if (oct >= 0xF0u) { /* Four octets. */
			zap_i02 chr =  ((zap_i02)oct ^ 0xF0u) << 0x12u;
			++src;
			chr           += ((zap_i02)*src ^ 0x80u) << 0xCu;
			++src;
			chr           += ((zap_i02)*src ^ 0x80u) << 0x6u;
			++src;
			chr           +=  (zap_i02)*src ^ 0x80u;
			++src;
			*dest = chr;
			continue;
		}
		if (oct >= 0xE0u) { /* Three octets. */
			zap_i02 chr =  ((zap_i02)oct ^ 0xE0u) << 0xCu;
			++src;
			chr           += ((zap_i02)*src ^ 0x80u) << 0x6u;
			++src;
			chr           +=  (zap_i02)*src ^ 0x80u;
			++src;
			*dest = chr;
			continue;
		}
		if (oct >= 0xC0u) { /* Two octets. */
			zap_i02 chr =  ((zap_i02)oct ^ 0xC0u) << 0x6u;
			++src;
			          chr +=  (zap_i02)*src ^ 0x80u;
			++src;
			*dest = chr;
			continue;
		}
		/* One octet. */
		*dest = oct;
		++src;
	}
}