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Changed to use shifting and masking

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Braedon 2018-04-25 16:26:57 +10:00 committed by GitHub
parent f6cbe9a9cc
commit 07af6559d8
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 14 deletions
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28
std/unicode.zig
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@ -35,25 +35,25 @@ pub fn utf8Encode(c: u32, out: []u8) !u3 {
if (utf8CodepointSequenceLength(c)) |length| {
debug.assert(out.len >= length);
switch (length) {
// The pattern for each is the same
// - Increasing the initial shift by 6 each time
// - Each time after the first shorten the shifted
// value to a max of 0b111111 (63)
1 => out[0] = u8(c), // Can just do 0 + codepoint for initial range
2 => {
// 64 to convert the codepoint into its segments
out[0] = u8(0b11000000 + c / 64);
out[1] = u8(0b10000000 + c % 64);
out[0] = u8(0b11000000 | (c >> 6));
out[1] = u8(0b10000000 | (c & 0b111111));
},
3 => {
// Again using 64 as a conversion into their segments
// But using C / 4096 (64 * 64) as the first, (C/64) % 64 as the second, and just C % 64 as the last
out[0] = u8(0b11100000 + c / 4096);
out[1] = u8(0b10000000 + (c / 64) % 64);
out[2] = u8(0b10000000 + c % 64);
out[0] = u8(0b11100000 | (c >> 12));
out[1] = u8(0b10000000 | ((c >> 6) & 0b111111));
out[2] = u8(0b10000000 | (c & 0b111111));
},
4 => {
// Same as previously but now its C / 64^3 (262144), (C / 4096) % 64, (C / 64) % 64 and C % 64
out[0] = u8(0b11110000 + c / 262144);
out[1] = u8(0b10000000 + (c / 4096) % 64);
out[2] = u8(0b10000000 + (c / 64) % 64);
out[3] = u8(0b10000000 + c % 64);
out[0] = u8(0b11110000 | (c >> 18));
out[1] = u8(0b10000000 | ((c >> 12) & 0b111111));
out[2] = u8(0b10000000 | ((c >> 6) & 0b111111));
out[3] = u8(0b10000000 | (c & 0b111111));
},
else => unreachable,
}
@ -257,7 +257,7 @@ fn testErrorEncode(codePoint: u32, array: []u8, expectedErr: error) void {
if (utf8Encode(codePoint, array)) |_| {
unreachable;
} else |err| {
assert(err == expectedErr);
debug.assert(err == expectedErr);
}
}