The Tor Browser / file comparison
comparison: xpcom/string/src/nsUTF8UtilsSSE2.cpp
xpcom/string/src/nsUTF8UtilsSSE2.cpp
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:7f97bf88272e |
|---|---|
| 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/. */ | |
| 4 | |
| 5 #include "nscore.h" | |
| 6 #include "nsAlgorithm.h" | |
| 7 #include <emmintrin.h> | |
| 8 #include <nsUTF8Utils.h> | |
| 9 | |
| 10 void | |
| 11 LossyConvertEncoding16to8::write_sse2(const char16_t* aSource, | |
| 12 uint32_t aSourceLength) | |
| 13 { | |
| 14 char* dest = mDestination; | |
| 15 | |
| 16 // Align source to a 16-byte boundary. | |
| 17 uint32_t i = 0; | |
| 18 uint32_t alignLen = | |
| 19 XPCOM_MIN<uint32_t>(aSourceLength, uint32_t(-NS_PTR_TO_INT32(aSource) & 0xf) / sizeof(char16_t)); | |
| 20 for (; i < alignLen; i++) { | |
| 21 dest[i] = static_cast<unsigned char>(aSource[i]); | |
| 22 } | |
| 23 | |
| 24 // Walk 64 bytes (four XMM registers) at a time. | |
| 25 __m128i vectmask = _mm_set1_epi16(0x00ff); | |
| 26 for (; aSourceLength - i > 31; i += 32) { | |
| 27 __m128i source1 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i)); | |
| 28 source1 = _mm_and_si128(source1, vectmask); | |
| 29 | |
| 30 __m128i source2 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 8)); | |
| 31 source2 = _mm_and_si128(source2, vectmask); | |
| 32 | |
| 33 __m128i source3 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 16)); | |
| 34 source3 = _mm_and_si128(source3, vectmask); | |
| 35 | |
| 36 __m128i source4 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 24)); | |
| 37 source4 = _mm_and_si128(source4, vectmask); | |
| 38 | |
| 39 | |
| 40 // Pack the source data. SSE2 views this as a saturating uint16_t to | |
| 41 // uint8_t conversion, but since we masked off the high-order byte of every | |
| 42 // uint16_t, we're really just grabbing the low-order bytes of source1 and | |
| 43 // source2. | |
| 44 __m128i packed1 = _mm_packus_epi16(source1, source2); | |
| 45 __m128i packed2 = _mm_packus_epi16(source3, source4); | |
| 46 | |
| 47 // This store needs to be unaligned since there's no guarantee that the | |
| 48 // alignment we did above for the source will align the destination. | |
| 49 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i), packed1); | |
| 50 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 16), packed2); | |
| 51 } | |
| 52 | |
| 53 // Finish up the rest. | |
| 54 for (; i < aSourceLength; i++) { | |
| 55 dest[i] = static_cast<unsigned char>(aSource[i]); | |
| 56 } | |
| 57 | |
| 58 mDestination += i; | |
| 59 } | |
| 60 | |
| 61 void | |
| 62 LossyConvertEncoding8to16::write_sse2(const char* aSource, | |
| 63 uint32_t aSourceLength) | |
| 64 { | |
| 65 char16_t *dest = mDestination; | |
| 66 | |
| 67 // Align source to a 16-byte boundary. We choose to align source rather than | |
| 68 // dest because we'd rather have our loads than our stores be fast. You have | |
| 69 // to wait for a load to complete, but you can keep on moving after issuing a | |
| 70 // store. | |
| 71 uint32_t i = 0; | |
| 72 uint32_t alignLen = XPCOM_MIN(aSourceLength, uint32_t(-NS_PTR_TO_INT32(aSource) & 0xf)); | |
| 73 for (; i < alignLen; i++) { | |
| 74 dest[i] = static_cast<unsigned char>(aSource[i]); | |
| 75 } | |
| 76 | |
| 77 // Walk 32 bytes (two XMM registers) at a time. | |
| 78 for (; aSourceLength - i > 31; i += 32) { | |
| 79 __m128i source1 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i)); | |
| 80 __m128i source2 = _mm_load_si128(reinterpret_cast<const __m128i*>(aSource + i + 16)); | |
| 81 | |
| 82 // Interleave 0s in with the bytes of source to create lo and hi. | |
| 83 __m128i lo1 = _mm_unpacklo_epi8(source1, _mm_setzero_si128()); | |
| 84 __m128i hi1 = _mm_unpackhi_epi8(source1, _mm_setzero_si128()); | |
| 85 __m128i lo2 = _mm_unpacklo_epi8(source2, _mm_setzero_si128()); | |
| 86 __m128i hi2 = _mm_unpackhi_epi8(source2, _mm_setzero_si128()); | |
| 87 | |
| 88 // store lo and hi into dest. | |
| 89 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i), lo1); | |
| 90 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 8), hi1); | |
| 91 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 16), lo2); | |
| 92 _mm_storeu_si128(reinterpret_cast<__m128i*>(dest + i + 24), hi2); | |
| 93 } | |
| 94 | |
| 95 // Finish up whatever's left. | |
| 96 for (; i < aSourceLength; i++) { | |
| 97 dest[i] = static_cast<unsigned char>(aSource[i]); | |
| 98 } | |
| 99 | |
| 100 mDestination += i; | |
| 101 } |
