Bitcode: Add SimpleBitstreamCursor::getPointerToByte, etc.

Add API to SimpleBitstreamCursor to allow users to translate between
byte addresses and pointers.

  - jumpToPointer: move the bit position to a particular pointer.
  - getPointerToByte: get the pointer for a particular byte.
  - getPointerToBit: get the pointer for the byte of the current bit.
  - getCurrentByteNo: convenience function for assertions and tests.

Mainly adds unit tests (getPointerToBit/Byte already has a use), but
also preparation for eventually using jumpToPointer.

llvm-svn: 264546

1 files changed, 43 insertions, 0 deletions

diff --git a/llvm/unittests/Bitcode/BitstreamReaderTest.cpp b/llvm/unittests/Bitcode/BitstreamReaderTest.cpp
index b11d7fd..80285b8 100644
--- a/llvm/unittests/Bitcode/BitstreamReaderTest.cpp
+++ b/llvm/unittests/Bitcode/BitstreamReaderTest.cpp
@@ -53,4 +53,47 @@ TEST(BitstreamReaderTest, AtEndOfStreamEmpty) {
   EXPECT_TRUE(Cursor.AtEndOfStream());
 }
 
+TEST(BitstreamReaderTest, getCurrentByteNo) {
+  uint8_t Bytes[] = {0x00, 0x01, 0x02, 0x03};
+  BitstreamReader Reader(std::begin(Bytes), std::end(Bytes));
+  SimpleBitstreamCursor Cursor(Reader);
+
+  for (unsigned I = 0, E = 33; I != E; ++I) {
+    EXPECT_EQ(I / 8, Cursor.getCurrentByteNo());
+    (void)Cursor.Read(1);
+  }
+  EXPECT_EQ(4u, Cursor.getCurrentByteNo());
+}
+
+TEST(BitstreamReaderTest, getPointerToByte) {
+  uint8_t Bytes[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
+  BitstreamReader Reader(std::begin(Bytes), std::end(Bytes));
+  SimpleBitstreamCursor Cursor(Reader);
+
+  for (unsigned I = 0, E = 8; I != E; ++I) {
+    EXPECT_EQ(Bytes + I, Cursor.getPointerToByte(I, 1));
+  }
+}
+
+TEST(BitstreamReaderTest, getPointerToBit) {
+  uint8_t Bytes[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
+  BitstreamReader Reader(std::begin(Bytes), std::end(Bytes));
+  SimpleBitstreamCursor Cursor(Reader);
+
+  for (unsigned I = 0, E = 8; I != E; ++I) {
+    EXPECT_EQ(Bytes + I, Cursor.getPointerToBit(I * 8, 1));
+  }
+}
+
+TEST(BitstreamReaderTest, jumpToPointer) {
+  uint8_t Bytes[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07};
+  BitstreamReader Reader(std::begin(Bytes), std::end(Bytes));
+  SimpleBitstreamCursor Cursor(Reader);
+
+  for (unsigned I : {0, 6, 2, 7}) {
+    Cursor.jumpToPointer(Bytes + I);
+    EXPECT_EQ(I, Cursor.getCurrentByteNo());
+  }
+}
+
 } // end anonymous namespace