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109 lines
2.9 KiB
Plaintext
109 lines
2.9 KiB
Plaintext
module std::encoding::hex;
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import std::encoding @norecurse;
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// The implementation is based on https://www.rfc-editor.org/rfc/rfc4648
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fn String encode_buffer(char[] code, char[] buffer)
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{
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return (String)buffer[:encode_bytes(code, buffer)];
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}
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fn char[]! decode_buffer(char[] code, char[] buffer)
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{
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return buffer[:decode_bytes(code, buffer)!];
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}
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fn String encode(Allocator allocator, char[] code)
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{
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char[] data = allocator::alloc_array(allocator, char, encode_len(code.len));
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return (String)data[:encode_bytes(code, data)];
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}
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fn char[]! decode(Allocator allocator, char[] code)
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{
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char[] data = allocator::alloc_array(allocator, char, decode_len(code.len));
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return data[:decode_bytes(code, data)!];
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}
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fn String tencode(char[] code) @inline => encode(tmem(), code);
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fn char[]! tdecode(char[] code) @inline => decode(tmem(), code);
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<*
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Calculate the size of the encoded data.
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@param n "Size of the input to be encoded."
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@return "The size of the input once encoded."
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*>
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fn usz encode_len(usz n) => n * 2;
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<*
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Encode the content of src into dst, which must be properly sized.
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@param src "The input to be encoded."
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@param dst "The encoded input."
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@return "The encoded size."
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@require dst.len >= encode_len(src.len) "Destination array is not large enough"
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*>
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fn usz encode_bytes(char[] src, char[] dst)
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{
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usz j = 0;
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foreach (v : src)
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{
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dst[j] = HEXALPHABET[v >> 4];
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dst[j + 1] = HEXALPHABET[v & 0x0f];
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j = j + 2;
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}
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return src.len * 2;
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}
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<*
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Calculate the size of the decoded data.
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@param n "Size of the input to be decoded."
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@return "The size of the input once decoded."
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*>
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macro usz decode_len(usz n) => n / 2;
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<*
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Decodes src into bytes. Returns the actual number of bytes written to dst.
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Expects that src only contains hexadecimal characters and that src has even
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length.
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@param src "The input to be decoded."
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@param dst "The decoded input."
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@require src.len % 2 == 0 "src is not of even length"
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@require dst.len >= decode_len(src.len) "Destination array is not large enough"
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@return! DecodingFailure.INVALID_CHARACTER
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*>
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fn usz! decode_bytes(char[] src, char[] dst)
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{
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usz i;
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for (usz j = 1; j < src.len; j += 2)
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{
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char a = HEXREVERSE[src[j - 1]];
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char b = HEXREVERSE[src[j]];
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if (a > 0x0f || b > 0x0f) return DecodingFailure.INVALID_CHARACTER?;
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dst[i] = (a << 4) | b;
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i++;
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}
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return i;
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}
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const char[?] HEXALPHABET @private = "0123456789abcdef";
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const char[?] HEXREVERSE @private =
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x`ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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00010203040506070809ffffffffffff
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ff0a0b0c0d0e0fffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ff0a0b0c0d0e0fffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff
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ffffffffffffffffffffffffffffffff`;
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