2 * Copyright 2016-present Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include <folly/experimental/Instructions.h>
19 #include <glog/logging.h>
21 #include <folly/portability/GTest.h>
23 using namespace folly;
24 using namespace folly::compression::instructions;
26 TEST(Instructions, BitExtraction) {
28 0b11111110'11011100'10111010'10011000'01110110'01010100'00110010'00010000;
30 if (not Haswell::supported()) {
34 LOG(INFO) << "Testing Haswell on supported machine";
36 // Extract 4 bits a time, starting from bit 0
37 uint64_t expected = 0;
38 for (int i = 0; i < 64 - 4; i += 4) {
39 EXPECT_EQ(expected, Default::bextr(value, i, 4));
40 EXPECT_EQ(expected, Haswell::bextr(value, i, 4));
44 // Extract 8 bits a time, starting from bit 1
45 uint64_t value2 = value << 1;
48 for (int i = 1; i < 64 - 8; i += 4) {
49 expected = (lower & 0xF) | ((upper & 0xF) << 4);
50 EXPECT_EQ(expected, Default::bextr(value2, i, 8));
51 EXPECT_EQ(expected, Haswell::bextr(value2, i, 8));
56 // Extract 16 bits a time, starting from bit 2
57 uint64_t value3 = value << 2;
62 for (int i = 2; i < 64 - 16; i += 4) {
63 expected = (part0 & 0xF) | ((part1 & 0xF) << 4) | ((part2 & 0xF) << 8) |
64 ((part3 & 0xF) << 12);
65 EXPECT_EQ(expected, Default::bextr(value3, i, 16));
66 EXPECT_EQ(expected, Haswell::bextr(value3, i, 16));
74 expected = 0b1011'1010'1001'1000'0111'0110'0101'0100;
75 EXPECT_EQ(expected, Default::bextr(value, 16, 32));
76 EXPECT_EQ(expected, Haswell::bextr(value, 16, 32));
78 // Extract all 64 bits
79 EXPECT_EQ(value, Default::bextr(value, 0, 64));
80 EXPECT_EQ(value, Haswell::bextr(value, 0, 64));
83 EXPECT_EQ(0, Default::bextr(value, 4, 0));
84 EXPECT_EQ(0, Haswell::bextr(value, 4, 0));
86 // Make sure only up to 63-th bits will be extracted
87 EXPECT_EQ(0b1111, Default::bextr(value, 60, 5));
88 EXPECT_EQ(0b1111, Haswell::bextr(value, 60, 5));
90 EXPECT_EQ(0, Default::bextr(value, 64, 8));
91 EXPECT_EQ(0, Haswell::bextr(value, 64, 8));
93 EXPECT_EQ(value, Default::bextr(value, 0, 65));
94 EXPECT_EQ(value, Haswell::bextr(value, 0, 65));