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utf8Decode4

unicode.utf8Decode4

pub fn utf8Decode4(bytes: [4]u8) Utf8Decode4Error!u21

File

lib/std/unicode.zig:165

Code

pub fn utf8Decode4(bytes: [4]u8) Utf8Decode4Error!u21 {
    assert(bytes[0] & 0b11111000 == 0b11110000);
    var value: u21 = bytes[0] & 0b00000111;

    if (bytes[1] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
    value <<= 6;
    value |= bytes[1] & 0b00111111;

    if (bytes[2] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
    value <<= 6;
    value |= bytes[2] & 0b00111111;

    if (bytes[3] & 0b11000000 != 0b10000000) return error.Utf8ExpectedContinuation;
    value <<= 6;
    value |= bytes[3] & 0b00111111;

    if (value < 0x10000) return error.Utf8OverlongEncoding;
    if (value > 0x10FFFF) return error.Utf8CodepointTooLarge;

    return value;
}