A possible, not optimized, SWAR approach without Vector API, searching for ASCII char

TryingSWAR.java

public class TryingSWAR{

public final static int[] findCharPositions(String input, byte target) {

		final byte[] bytes = input.getBytes(StandardCharsets.UTF_8);
		final int trail = bytes.length;
		final int[] positions = new int[trail];
		final long pattern = 0x0101010101010101L * (target & 0xFF);
		int i = 0, idx = 0;

		if (trail > 8) {
			final ByteBuffer buf = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
			for (int len = trail - 8; i <= len;) {
				long chunk = buf.getLong(i);
		        long filteredChunk = (chunk ^ pattern) - 0x0101010101010101L & ~(chunk ^ pattern) & 0x8080808080808080L;

				if (filteredChunk != 0) {
					if ((filteredChunk & 0x0000000000000080L) != 0)
						positions[idx++] = i;
					if ((filteredChunk & 0x0000000000008000L) != 0)
						positions[idx++] = i + 1;
					if ((filteredChunk & 0x0000000000800000L) != 0)
						positions[idx++] = i + 2;
					if ((filteredChunk & 0x0000000080000000L) != 0)
						positions[idx++] = i + 3;
					if ((filteredChunk & 0x0000008000000000L) != 0)
						positions[idx++] = i + 4;
					if ((filteredChunk & 0x0000800000000000L) != 0)
						positions[idx++] = i + 5;
					if ((filteredChunk & 0x0080000000000000L) != 0)
						positions[idx++] = i + 6;
					if ((filteredChunk & 0x8000000000000000L) != 0)
						positions[idx++] = i + 7;
				}
				i += 8;
			}
			for (; i < trail; i++) {
				if (bytes[i] == target) {
					positions[idx++] = i;
				}
			}
		} else {
			for (; i < trail; i++) {
				if (bytes[i] == target) {
					positions[i] = i;
				}
			}
		}

		return positions;
	}


}