1 files changed, 23 insertions, 0 deletions
diff --git a/core/fxcrt/fx_extension_unittest.cpp b/core/fxcrt/fx_extension_unittest.cpp
index 38b66ba2d2..0500a14b6f 100644
--- a/core/fxcrt/fx_extension_unittest.cpp
+++ b/core/fxcrt/fx_extension_unittest.cpp
@@ -5,6 +5,19 @@
 #include "core/fxcrt/fx_extension.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+namespace {
+
+uint32_t ReferenceGetBits32(const uint8_t* pData, int bitpos, int nbits) {
+  int result = 0;
+  for (int i = 0; i < nbits; i++) {
+    if (pData[(bitpos + i) / 8] & (1 << (7 - (bitpos + i) % 8)))
+      result |= 1 << (nbits - i - 1);
+  }
+  return result;
+}
+
+}  // namespace
+
 TEST(fxcrt, FXSYS_HexCharToInt) {
   EXPECT_EQ(10, FXSYS_HexCharToInt('a'));
   EXPECT_EQ(10, FXSYS_HexCharToInt('A'));
@@ -89,3 +102,13 @@ TEST(fxcrt, FXSYS_ToUTF16BE) {
   EXPECT_EQ(8U, FXSYS_ToUTF16BE(0x2003E, buf));
   EXPECT_STREQ("D840DC3E", buf);
 }
+
+TEST(fxcrt, GetBits32) {
+  unsigned char data[] = {0xDE, 0x3F, 0xB1, 0x7C, 0x12, 0x9A, 0x04, 0x56};
+  for (int nbits = 1; nbits <= 32; ++nbits) {
+    for (int bitpos = 0; bitpos < (int)sizeof(data) * 8 - nbits; ++bitpos) {
+      EXPECT_EQ(ReferenceGetBits32(data, bitpos, nbits),
+                GetBits32(data, bitpos, nbits));
+    }
+  }
+}