Adding upstream version 0.11.1.upstream/0.11.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 237 insertions, 0 deletions

diff --git a/src/simdutf8check.h b/src/simdutf8check.h
new file mode 100644
index 0000000..4a3a364
--- /dev/null
+++ b/src/simdutf8check.h
@@ -0,0 +1,237 @@
+/**
+ * https://github.com/lemire/fastvalidate-utf-8
+ */
+
+#ifndef SIMDUTF8CHECK_H
+#define SIMDUTF8CHECK_H
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <x86intrin.h>
+
+#include "base/lnav_log.hh"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * legal utf-8 byte sequence
+ * http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
+ *
+ *  Code Points        1st       2s       3s       4s
+ * U+0000..U+007F     00..7F
+ * U+0080..U+07FF     C2..DF   80..BF
+ * U+0800..U+0FFF     E0       A0..BF   80..BF
+ * U+1000..U+CFFF     E1..EC   80..BF   80..BF
+ * U+D000..U+D7FF     ED       80..9F   80..BF
+ * U+E000..U+FFFF     EE..EF   80..BF   80..BF
+ * U+10000..U+3FFFF   F0       90..BF   80..BF   80..BF
+ * U+40000..U+FFFFF   F1..F3   80..BF   80..BF   80..BF
+ * U+100000..U+10FFFF F4       80..8F   80..BF   80..BF
+ *
+ */
+
+// all byte values must be no larger than 0xF4
+static void checkSmallerThan0xF4(__m128i current_bytes,
+                                        __m128i *has_error)
+{
+    // unsigned, saturates to 0 below max
+    *has_error = _mm_or_si128(*has_error,
+                              _mm_subs_epu8(current_bytes,
+                                            _mm_set1_epi8(0xF4)));
+}
+
+static __m128i continuationLengths(__m128i high_nibbles)
+{
+    return _mm_shuffle_epi8(
+        _mm_setr_epi8(1, 1, 1, 1, 1, 1, 1, 1, // 0xxx (ASCII)
+                      0, 0, 0, 0,             // 10xx (continuation)
+                      2, 2,                   // 110x
+                      3,                      // 1110
+                      4), // 1111, next should be 0 (not checked here)
+        high_nibbles);
+}
+
+static __m128i carryContinuations(__m128i initial_lengths,
+                                         __m128i previous_carries)
+{
+
+    __m128i right1 = _mm_subs_epu8(
+        _mm_alignr_epi8(initial_lengths, previous_carries, 16 - 1),
+        _mm_set1_epi8(1));
+    __m128i sum = _mm_add_epi8(initial_lengths, right1);
+
+    __m128i right2 = _mm_subs_epu8(
+        _mm_alignr_epi8(sum, previous_carries, 16 - 2),
+        _mm_set1_epi8(2));
+    return _mm_add_epi8(sum, right2);
+}
+
+static void checkContinuations(__m128i initial_lengths,
+                                      __m128i carries,
+                                      __m128i *has_error)
+{
+
+    // overlap || underlap
+    // carry > length && length > 0 || !(carry > length) && !(length > 0)
+    // (carries > length) == (lengths > 0)
+    __m128i overunder = _mm_cmpeq_epi8(
+        _mm_cmpgt_epi8(carries, initial_lengths),
+        _mm_cmpgt_epi8(initial_lengths, _mm_setzero_si128()));
+
+    *has_error = _mm_or_si128(*has_error, overunder);
+}
+
+// when 0xED is found, next byte must be no larger than 0x9F
+// when 0xF4 is found, next byte must be no larger than 0x8F
+// next byte must be continuation, ie sign bit is set, so signed < is ok
+static void checkFirstContinuationMax(__m128i current_bytes,
+                                             __m128i off1_current_bytes,
+                                             __m128i *has_error)
+{
+    __m128i maskED = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xED));
+    __m128i maskF4 = _mm_cmpeq_epi8(off1_current_bytes, _mm_set1_epi8(0xF4));
+
+    __m128i badfollowED = _mm_and_si128(
+        _mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x9F)),
+        maskED);
+    __m128i badfollowF4 = _mm_and_si128(
+        _mm_cmpgt_epi8(current_bytes, _mm_set1_epi8(0x8F)),
+        maskF4);
+
+    *has_error = _mm_or_si128(*has_error,
+                              _mm_or_si128(badfollowED, badfollowF4));
+}
+
+// map off1_hibits => error condition
+// hibits     off1    cur
+// C       => < C2 && true  
+// E       => < E1 && < A0
+// F       => < F1 && < 90
+// else      false && false
+static void checkOverlong(__m128i current_bytes,
+                                 __m128i off1_current_bytes,
+                                 __m128i hibits,
+                                 __m128i previous_hibits,
+                                 __m128i *has_error)
+{
+    __m128i off1_hibits = _mm_alignr_epi8(hibits, previous_hibits, 16 - 1);
+    __m128i initial_mins = _mm_shuffle_epi8(
+        _mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
+                      -128, -128, -128, -128,  // 10xx => false
+                      0xC2, -128, // 110x
+                      0xE1, // 1110
+                      0xF1),
+        off1_hibits);
+
+    __m128i initial_under = _mm_cmpgt_epi8(initial_mins, off1_current_bytes);
+
+    __m128i second_mins = _mm_shuffle_epi8(
+        _mm_setr_epi8(-128, -128, -128, -128, -128, -128, -128, -128,
+                      -128, -128, -128, -128,  // 10xx => false
+                      127, 127, // 110x => true
+                      0xA0, // 1110
+                      0x90),
+        off1_hibits);
+    __m128i second_under = _mm_cmpgt_epi8(second_mins, current_bytes);
+    *has_error = _mm_or_si128(*has_error,
+                              _mm_and_si128(initial_under, second_under));
+}
+
+struct processed_utf_bytes {
+    __m128i rawbytes;
+    __m128i high_nibbles;
+    __m128i carried_continuations;
+};
+
+static void count_nibbles(__m128i bytes,
+                                 struct processed_utf_bytes *answer)
+{
+    answer->rawbytes = bytes;
+    answer->high_nibbles = _mm_and_si128(_mm_srli_epi16(bytes, 4),
+                                         _mm_set1_epi8(0x0F));
+}
+
+// check whether the current bytes are valid UTF-8
+// at the end of the function, previous gets updated
+static struct processed_utf_bytes
+checkUTF8Bytes(__m128i current_bytes, struct processed_utf_bytes *previous,
+               __m128i *has_error)
+{
+    struct processed_utf_bytes pb;
+    count_nibbles(current_bytes, &pb);
+
+    checkSmallerThan0xF4(current_bytes, has_error);
+
+    __m128i initial_lengths = continuationLengths(pb.high_nibbles);
+
+    pb.carried_continuations = carryContinuations(
+        initial_lengths,
+        previous->carried_continuations);
+
+    checkContinuations(initial_lengths, pb.carried_continuations, has_error);
+
+    __m128i off1_current_bytes =
+        _mm_alignr_epi8(pb.rawbytes, previous->rawbytes, 16 - 1);
+    checkFirstContinuationMax(current_bytes, off1_current_bytes,
+                              has_error);
+
+    checkOverlong(current_bytes, off1_current_bytes,
+                  pb.high_nibbles, previous->high_nibbles, has_error);
+    return pb;
+}
+
+static bool validate_utf8_fast(const char *src, size_t len, ssize_t *len_out)
+{
+    size_t i = 0, orig_len = len;
+    __m128i has_error = _mm_setzero_si128();
+    __m128i lfchars = _mm_set1_epi8('\n');
+    __m128i lfresult = _mm_setzero_si128();
+    struct processed_utf_bytes previous = {.rawbytes = _mm_setzero_si128(),
+        .high_nibbles = _mm_setzero_si128(),
+        .carried_continuations = _mm_setzero_si128()};
+    if (len >= 16) {
+        for (; i <= len - 16; i += 16) {
+            __m128i current_bytes = _mm_loadu_si128(
+                (const __m128i *) (src + i));
+            previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
+            lfresult = _mm_cmpeq_epi8(current_bytes, lfchars);
+            if (_mm_movemask_epi8(lfresult)) {
+                for (; src[i] != '\n'; i++) {
+                }
+                len = i;
+                break;
+            }
+        }
+    }
+
+    //last part
+    if (i < len) {
+        char buffer[16];
+        memset(buffer, 0, 16);
+        memcpy(buffer, src + i, len - i);
+        __m128i current_bytes = _mm_loadu_si128((const __m128i *) (buffer));
+        previous = checkUTF8Bytes(current_bytes, &previous, &has_error);
+        for (; i < len && src[i] != '\n'; i++) {
+        }
+    } else {
+        has_error = _mm_or_si128(_mm_cmpgt_epi8(previous.carried_continuations,
+                                                _mm_setr_epi8(9, 9, 9, 9, 9, 9,
+                                                              9, 9, 9, 9, 9, 9,
+                                                              9, 9, 9, 1)),
+                                 has_error);
+    }
+
+    if (i < orig_len && src[i] == '\n') {
+        *len_out = i;
+    }
+
+    return _mm_testz_si128(has_error, has_error);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif