1 files changed, 41 insertions, 0 deletions
diff --git a/include/llvm/Support/DataExtractor.h b/include/llvm/Support/DataExtractor.h
index 380b628fd95ff..31447882a9196 100644
--- a/include/llvm/Support/DataExtractor.h
+++ b/include/llvm/Support/DataExtractor.h
@@ -14,6 +14,30 @@
 #include "llvm/Support/DataTypes.h"
 
 namespace llvm {
+
+/// An auxiliary type to facilitate extraction of 3-byte entities. 
+struct Uint24 {
+  uint8_t Bytes[3];
+  Uint24(uint8_t U) {
+    Bytes[0] = Bytes[1] = Bytes[2] = U;
+  }
+  Uint24(uint8_t U0, uint8_t U1, uint8_t U2) {
+    Bytes[0] = U0; Bytes[1] = U1; Bytes[2] = U2;
+  }
+  uint32_t getAsUint32(bool IsLittleEndian) const {
+    int LoIx = IsLittleEndian ? 0 : 2;
+    return Bytes[LoIx] + (Bytes[1] << 8) + (Bytes[2-LoIx] << 16);
+  }
+};
+
+using uint24_t = Uint24;
+static_assert(sizeof(uint24_t) == 3, "sizeof(uint24_t) != 3");
+
+/// Needed by swapByteOrder().
+inline uint24_t getSwappedBytes(uint24_t C) {
+  return uint24_t(C.Bytes[2], C.Bytes[1], C.Bytes[0]);
+}
+
 class DataExtractor {
   StringRef Data;
   uint8_t IsLittleEndian;
@@ -236,6 +260,23 @@ public:
   ///     NULL otherise.
   uint16_t *getU16(uint32_t *offset_ptr, uint16_t *dst, uint32_t count) const;
 
+  /// Extract a 24-bit unsigned value from \a *offset_ptr and return it
+  /// in a uint32_t.
+  ///
+  /// Extract 3 bytes from the binary data at the offset pointed to by
+  /// \a offset_ptr, construct a uint32_t from them and update the offset
+  /// on success.
+  ///
+  /// @param[in,out] offset_ptr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the 3 bytes if the value is extracted correctly. If the offset
+  ///     is out of bounds or there are not enough bytes to extract this value,
+  ///     the offset will be left unmodified.
+  ///
+  /// @return
+  ///     The extracted 24-bit value represented in a uint32_t.
+  uint32_t getU24(uint32_t *offset_ptr) const;
+
   /// Extract a uint32_t value from \a *offset_ptr.
   ///
   /// Extract a single uint32_t from the binary data at the offset