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AK: Add a simple and inefficient Base64 encoder

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The test cases are taken from RFC 4648.
This commit is contained in:
Tom Lebreux 2020-06-12 22:09:31 -04:00 • committed by Andreas Kling
parent dd53e070c5
commit 79529ffd47
Notes: sideshowbarker 2024-07-19 05:33:11 +09:00
3 changed files with 92 additions and 0 deletions
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40
AK/Base64.cpp
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@ -84,4 +84,44 @@ ByteBuffer decode_base64(const StringView& input)
return ByteBuffer::copy(output.data(), output.size());
}
ByteBuffer encode_base64(const StringView& input)
{
Vector<u8> output;
auto get = [&](size_t offset, bool* need_padding = nullptr) -> u8 {
if (offset >= input.length()) {
if (need_padding)
*need_padding = true;
return 0;
}
return (u8)input[offset];
};
for (size_t i = 0; i < input.length(); i += 3) {
bool is_8bit = false;
bool is_16bit = false;
u8 in0 = get(i);
u8 in1 = get(i + 1, &is_16bit);
u8 in2 = get(i + 2, &is_8bit);
u8 index0 = (in0 >> 2) & 0x3f;
u8 index1 = ((in0 << 4) | (in1 >> 4)) & 0x3f;
u8 index2 = ((in1 << 2) | (in2 >> 6)) & 0x3f;
u8 index3 = in2 & 0x3f;
u8 out0 = s_alphabet[index0];
u8 out1 = s_alphabet[index1];
u8 out2 = is_16bit ? '=' : s_alphabet[index2];
u8 out3 = is_8bit ? '=' : s_alphabet[index3];
output.append(out0);
output.append(out1);
output.append(out2);
output.append(out3);
}
return ByteBuffer::copy(output.data(), output.size());
}
}