// Generates code for every target that this compiler can support. #undef HWY_TARGET_INCLUDE #define HWY_TARGET_INCLUDE "simd/vt.cpp" // this file #include // must come before highway.h #include #include #include #include HWY_BEFORE_NAMESPACE(); namespace ghostty { namespace HWY_NAMESPACE { namespace hn = hwy::HWY_NAMESPACE; using T = uint8_t; // Compute the length of the maximal subpart of an ill-formed UTF-8 // subsequence starting at p[0], per Unicode Table 3-7 and the W3C // "U+FFFD Substitution of Maximal Subparts" algorithm. // // The maximal subpart is the longest initial subsequence that is either: // (a) the start of a well-formed sequence, or // (b) a single byte. // Each maximal subpart maps to exactly one U+FFFD. static size_t MaximalSubpart(const unsigned char* p, size_t len) { if (len == 0) return 0; unsigned char b0 = p[0]; // Continuation bytes (80-BF), overlong leads (C0-C1), or invalid (F5-FF): // each is its own maximal subpart of length 1. if (b0 < 0xC2 || b0 > 0xF4) return 1; // Determine the expected sequence length and the valid range for each // continuation byte per Unicode Table 3-7. size_t seq_len; unsigned char lo[3], hi[3]; if (b0 <= 0xDF) { seq_len = 2; lo[0] = 0x80; hi[0] = 0xBF; } else if (b0 == 0xE0) { seq_len = 3; lo[0] = 0xA0; hi[0] = 0xBF; lo[1] = 0x80; hi[1] = 0xBF; } else if (b0 <= 0xEC) { seq_len = 3; lo[0] = 0x80; hi[0] = 0xBF; lo[1] = 0x80; hi[1] = 0xBF; } else if (b0 == 0xED) { seq_len = 3; lo[0] = 0x80; hi[0] = 0x9F; lo[1] = 0x80; hi[1] = 0xBF; } else if (b0 <= 0xEF) { seq_len = 3; lo[0] = 0x80; hi[0] = 0xBF; lo[1] = 0x80; hi[1] = 0xBF; } else if (b0 == 0xF0) { seq_len = 4; lo[0] = 0x90; hi[0] = 0xBF; lo[1] = 0x80; hi[1] = 0xBF; lo[2] = 0x80; hi[2] = 0xBF; } else if (b0 <= 0xF3) { seq_len = 4; lo[0] = 0x80; hi[0] = 0xBF; lo[1] = 0x80; hi[1] = 0xBF; lo[2] = 0x80; hi[2] = 0xBF; } else { // b0 == 0xF4 seq_len = 4; lo[0] = 0x80; hi[0] = 0x8F; lo[1] = 0x80; hi[1] = 0xBF; lo[2] = 0x80; hi[2] = 0xBF; } // Check continuation bytes against their specific valid ranges. // The maximal subpart extends as far as bytes match. size_t valid = 1; // lead byte counts for (size_t i = 0; i < seq_len - 1 && valid < len; i++) { unsigned char cb = p[valid]; if (cb < lo[i] || cb > hi[i]) break; valid++; } // If we matched all bytes, the sequence is structurally valid // (shouldn't happen since we're called on an error), but cap // to avoid skipping a valid sequence. if (valid == seq_len) return valid; return valid; } // Trim trailing bytes that form a valid-but-incomplete UTF-8 sequence. // Only trims sequences whose bytes so far match Table 3-7 ranges (i.e., // truly partial sequences that could be completed by future input). // Invalid lead bytes (C0, C1, F5-FF) or mismatched continuations are NOT // trimmed — they will be handled as errors by DecodeUTF8. static size_t TrimValidPartialUTF8(const uint8_t* input, size_t len) { if (len == 0) return 0; // Find the start of a potential trailing partial sequence by scanning // backwards from the end. We look for a lead byte (C2-F4) that could // start a multi-byte sequence, possibly followed by continuation bytes. // // We check up to the last 4 bytes (max UTF-8 sequence length). size_t check_start = len > 4 ? len - 4 : 0; for (size_t pos = len; pos > check_start; pos--) { unsigned char b = input[pos - 1]; // Skip continuation bytes — they might belong to the partial sequence. if ((b & 0xC0) == 0x80) continue; // Found a non-continuation byte. Only valid multi-byte leads (C2-F4) // can start a partial sequence worth trimming. Anything else (ASCII, // C0, C1, F5-FF) should be consumed by DecodeUTF8. if (b < 0xC2 || b > 0xF4) return len; // Determine expected sequence length from the lead byte. size_t expected; if (b <= 0xDF) expected = 2; else if (b <= 0xEF) expected = 3; else expected = 4; size_t seq_remaining = len - (pos - 1); // If we have all expected bytes, the sequence is complete (not partial). if (seq_remaining >= expected) return len; // Check if the trailing bytes form a valid prefix using MaximalSubpart. const unsigned char* seq_start = input + pos - 1; size_t subpart = MaximalSubpart(seq_start, seq_remaining); // Only trim if ALL trailing bytes are part of the valid prefix // (the sequence is valid-so-far but incomplete). if (subpart == seq_remaining) { return pos - 1; } // The sequence is ill-formed, don't trim — let DecodeUTF8 handle it. return len; } return len; } // Decode the UTF-8 text in input into output. Returns the number of decoded // characters. This function assumes output is large enough. // // This function handles malformed UTF-8 sequences by inserting a // replacement character (U+FFFD) following the W3C/Unicode "U+FFFD // Substitution of Maximal Subparts" algorithm and continuing to decode. // This function will consume the entire input no matter what. size_t DecodeUTF8(const uint8_t* HWY_RESTRICT input, size_t count, char32_t* output) { // Its possible for our input to be empty since DecodeUTF8UntilControlSeq // doesn't check for this. if (count == 0) { return 0; } // Decode UTF-8 to UTF-32, replacing invalid sequences with U+FFFD. const char* in = reinterpret_cast(input); size_t remaining = count; char32_t* out = output; while (remaining > 0) { auto r = simdutf::convert_utf8_to_utf32_with_errors(in, remaining, out); // If the decode was a full success then we're done! if (r.error == simdutf::SUCCESS) { out += r.count; break; } // On error, r.count is the input byte position of the error. // The output buffer is already written up to that point, but // we need count_utf8 to find how many char32_t that produced. out += simdutf::count_utf8(in, r.count); // Compute the maximal subpart at the error position and emit // a single U+FFFD for it. const unsigned char* err_pos = reinterpret_cast(in + r.count); size_t err_remaining = remaining - r.count; size_t skip = r.count + MaximalSubpart(err_pos, err_remaining); *out++ = 0xFFFD; in += skip; remaining -= skip; } return static_cast(out - output); } /// Decode the UTF-8 text in input into output until an escape /// character is found. This returns the number of bytes consumed /// from input and writes the number of decoded characters into /// output_count. /// /// This may return a value less than count even with no escape /// character if the input ends with an incomplete UTF-8 sequence. /// The caller should check the next byte manually to determine /// if it is incomplete. template size_t DecodeUTF8UntilControlSeqImpl(D d, const T* HWY_RESTRICT input, size_t count, char32_t* output, size_t* output_count) { const size_t N = hn::Lanes(d); // Create a vector containing ESC since that denotes a control sequence. const hn::Vec esc_vec = Set(d, 0x1B); // Compare N elements at a time. size_t i = 0; for (; i + N <= count; i += N) { // Load the N elements from our input into a vector. const hn::Vec input_vec = hn::LoadU(d, input + i); // If we don't have any escapes we keep going. We want to accumulate // the largest possible valid UTF-8 sequence before decoding. // TODO(mitchellh): benchmark this vs decoding every time const size_t esc_idx = IndexOfChunk(d, esc_vec, input_vec); if (esc_idx == kNotFound) { continue; } // We have an ESC char, decode up to this point. We start by assuming // a valid UTF-8 sequence and slow-path into error handling if we find // an invalid sequence. *output_count = DecodeUTF8(input, i + esc_idx, output); return i + esc_idx; } // If we have leftover input then we decode it one byte at a time (slow!) // using pretty much the same logic as above. if (i != count) { const hn::CappedTag d1; using D1 = decltype(d1); const hn::Vec esc1 = Set(d1, hn::GetLane(esc_vec)); for (; i < count; ++i) { const hn::Vec input_vec = hn::LoadU(d1, input + i); const size_t esc_idx = IndexOfChunk(d1, esc1, input_vec); if (esc_idx == kNotFound) { continue; } *output_count = DecodeUTF8(input, i + esc_idx, output); return i + esc_idx; } } // If we reached this point, its possible for our input to have an // incomplete sequence because we're consuming the full input. We need // to trim any incomplete sequences from the end of the input. // // We use our own trim instead of simdutf::trim_partial_utf8 because // we only want to trim sequences that are valid-so-far (true partial // sequences that may be completed by future input). Invalid bytes // like C0, C1, F5-FF should NOT be trimmed — they should be passed // through to DecodeUTF8 which will replace them with U+FFFD per the // maximal subpart algorithm. const size_t trimmed_len = TrimValidPartialUTF8(input, i); *output_count = DecodeUTF8(input, trimmed_len, output); return trimmed_len; } size_t DecodeUTF8UntilControlSeq(const uint8_t* HWY_RESTRICT input, size_t count, char32_t* output, size_t* output_count) { const hn::ScalableTag d; return DecodeUTF8UntilControlSeqImpl(d, input, count, output, output_count); } } // namespace HWY_NAMESPACE } // namespace ghostty HWY_AFTER_NAMESPACE(); // HWY_ONCE is true for only one of the target passes #if HWY_ONCE namespace ghostty { HWY_EXPORT(DecodeUTF8UntilControlSeq); size_t DecodeUTF8UntilControlSeq(const uint8_t* HWY_RESTRICT input, size_t count, char32_t* output, size_t* output_count) { return HWY_DYNAMIC_DISPATCH(DecodeUTF8UntilControlSeq)(input, count, output, output_count); } } // namespace ghostty extern "C" { size_t ghostty_simd_decode_utf8_until_control_seq(const uint8_t* HWY_RESTRICT input, size_t count, char32_t* output, size_t* output_count) { return ghostty::DecodeUTF8UntilControlSeq(input, count, output, output_count); } } // extern "C" #endif // HWY_ONCE