The Tor Browser: intl/uconv/src/nsUTF8ToUnicodeSSE2.cpp@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 // This file should only be compiled if you're on x86 or x86_64.  Additionally,

     6 // you'll need to compile this file with -msse2 if you're using gcc.

     8 #include <emmintrin.h>

     9 #include "nscore.h"

    11 namespace mozilla {

    12 namespace SSE2 {

    14 void

    15 Convert_ascii_run(const char *&src,

    16                   char16_t  *&dst,

    17                   int32_t      len)

    18 {

    19   if (len > 15) {

    20     __m128i in, out1, out2;

    21     __m128d *outp1, *outp2;

    22     __m128i zeroes;

    23     uint32_t offset;

    25     // align input to 16 bytes

    26     while ((NS_PTR_TO_UINT32(src) & 15) && len > 0) {

    27       if (*src & 0x80U)

    28         return;

    29       *dst++ = (char16_t) *src++;

    30       len--;

    31     }

    33     zeroes = _mm_setzero_si128();

    35     offset = NS_PTR_TO_UINT32(dst) & 15;

    37     // Note: all these inner loops have to break, not return; we need

    38     // to let the single-char loop below catch any leftover

    39     // byte-at-a-time ASCII chars, since this function must consume

    40     // all available ASCII chars before it returns

    42     if (offset == 0) {

    43       while (len > 15) {

    44         in = _mm_load_si128((__m128i *) src);

    45         if (_mm_movemask_epi8(in))

    46           break;

    47         out1 = _mm_unpacklo_epi8(in, zeroes);

    48         out2 = _mm_unpackhi_epi8(in, zeroes);

    49         _mm_stream_si128((__m128i *) dst, out1);

    50         _mm_stream_si128((__m128i *) (dst + 8), out2);

    51         dst += 16;

    52         src += 16;

    53         len -= 16;

    54       }

    55     } else if (offset == 8) {

    56       outp1 = (__m128d *) &out1;

    57       outp2 = (__m128d *) &out2;

    58       while (len > 15) {

    59         in = _mm_load_si128((__m128i *) src);

    60         if (_mm_movemask_epi8(in))

    61           break;

    62         out1 = _mm_unpacklo_epi8(in, zeroes);

    63         out2 = _mm_unpackhi_epi8(in, zeroes);

    64         _mm_storel_epi64((__m128i *) dst, out1);

    65         _mm_storel_epi64((__m128i *) (dst + 8), out2);

    66         _mm_storeh_pd((double *) (dst + 4), *outp1);

    67         _mm_storeh_pd((double *) (dst + 12), *outp2);

    68         src += 16;

    69         dst += 16;

    70         len -= 16;

    71       }

    72     } else {

    73       while (len > 15) {

    74         in = _mm_load_si128((__m128i *) src);

    75         if (_mm_movemask_epi8(in))

    76           break;

    77         out1 = _mm_unpacklo_epi8(in, zeroes);

    78         out2 = _mm_unpackhi_epi8(in, zeroes);

    79         _mm_storeu_si128((__m128i *) dst, out1);

    80         _mm_storeu_si128((__m128i *) (dst + 8), out2);

    81         src += 16;

    82         dst += 16;

    83         len -= 16;

    84       }

    85     }

    86   }

    88   // finish off a byte at a time

    90   while (len-- > 0 && (*src & 0x80U) == 0) {

    91     *dst++ = (char16_t) *src++;

    92   }

    93 }

    95 } // namespace SSE2

    96 } // namespace mozilla

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