1 files changed, 138 insertions, 0 deletions
diff --git a/include/clang/Basic/FixedPoint.h b/include/clang/Basic/FixedPoint.h
new file mode 100644
index 0000000000000..9a9b7cc9c1fbc
--- /dev/null
+++ b/include/clang/Basic/FixedPoint.h
@@ -0,0 +1,138 @@
+//===- FixedPoint.h - Fixed point constant handling -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// Defines the fixed point number interface.
+/// This is a class for abstracting various operations performed on fixed point
+/// types described in ISO/IEC JTC1 SC22 WG14 N1169 starting at clause 4.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_BASIC_FIXEDPOINT_H
+#define LLVM_CLANG_BASIC_FIXEDPOINT_H
+
+#include "llvm/ADT/APSInt.h"
+
+namespace clang {
+
+class ASTContext;
+class QualType;
+
+/// The fixed point semantics work similarly to llvm::fltSemantics. The width
+/// specifies the whole bit width of the underlying scaled integer (with padding
+/// if any). The scale represents the number of fractional bits in this type.
+/// When HasUnsignedPadding is true and this type is signed, the first bit
+/// in the value this represents is treaded as padding.
+class FixedPointSemantics {
+public:
+  FixedPointSemantics(unsigned Width, unsigned Scale, bool IsSigned,
+                      bool IsSaturated, bool HasUnsignedPadding)
+      : Width(Width), Scale(Scale), IsSigned(IsSigned),
+        IsSaturated(IsSaturated), HasUnsignedPadding(HasUnsignedPadding) {
+    assert(Width >= Scale && "Not enough room for the scale");
+  }
+
+  unsigned getWidth() const { return Width; }
+  unsigned getScale() const { return Scale; }
+  bool isSigned() const { return IsSigned; }
+  bool isSaturated() const { return IsSaturated; }
+  bool hasUnsignedPadding() const { return HasUnsignedPadding; }
+
+  void setSaturated(bool Saturated) { IsSaturated = Saturated; }
+
+  unsigned getIntegralBits() const {
+    if (IsSigned || (!IsSigned && HasUnsignedPadding))
+      return Width - Scale - 1;
+    else
+      return Width - Scale;
+  }
+
+private:
+  unsigned Width;
+  unsigned Scale;
+  bool IsSigned;
+  bool IsSaturated;
+  bool HasUnsignedPadding;
+};
+
+/// The APFixedPoint class works similarly to APInt/APSInt in that it is a
+/// functional replacement for a scaled integer. It is meant to replicate the
+/// fixed point types proposed in ISO/IEC JTC1 SC22 WG14 N1169. The class carries
+/// info about the fixed point type's width, sign, scale, and saturation, and
+/// provides different operations that would normally be performed on fixed point
+/// types.
+///
+/// Semantically this does not represent any existing C type other than fixed
+/// point types and should eventually be moved to LLVM if fixed point types gain
+/// native IR support.
+class APFixedPoint {
+ public:
+   APFixedPoint(const llvm::APInt &Val, const FixedPointSemantics &Sema)
+       : Val(Val, !Sema.isSigned()), Sema(Sema) {
+     assert(Val.getBitWidth() == Sema.getWidth() &&
+            "The value should have a bit width that matches the Sema width");
+   }
+
+   APFixedPoint(uint64_t Val, const FixedPointSemantics &Sema)
+       : APFixedPoint(llvm::APInt(Sema.getWidth(), Val, Sema.isSigned()),
+                      Sema) {}
+
+   llvm::APSInt getValue() const { return llvm::APSInt(Val, !Sema.isSigned()); }
+   inline unsigned getWidth() const { return Sema.getWidth(); }
+   inline unsigned getScale() const { return Sema.getScale(); }
+   inline bool isSaturated() const { return Sema.isSaturated(); }
+   inline bool isSigned() const { return Sema.isSigned(); }
+   inline bool hasPadding() const { return Sema.hasUnsignedPadding(); }
+
+   // Convert this number to match the semantics provided.
+   APFixedPoint convert(const FixedPointSemantics &DstSema) const;
+
+   APFixedPoint shr(unsigned Amt) const {
+     return APFixedPoint(Val >> Amt, Sema);
+  }
+
+  APFixedPoint shl(unsigned Amt) const {
+    return APFixedPoint(Val << Amt, Sema);
+  }
+
+  llvm::APSInt getIntPart() const {
+    if (Val < 0 && Val != -Val) // Cover the case when we have the min val
+      return -(-Val >> getScale());
+    else
+      return Val >> getScale();
+  }
+
+  // If LHS > RHS, return 1. If LHS == RHS, return 0. If LHS < RHS, return -1.
+  int compare(const APFixedPoint &Other) const;
+  bool operator==(const APFixedPoint &Other) const {
+    return compare(Other) == 0;
+  }
+  bool operator!=(const APFixedPoint &Other) const {
+    return compare(Other) != 0;
+  }
+  bool operator>(const APFixedPoint &Other) const { return compare(Other) > 0; }
+  bool operator<(const APFixedPoint &Other) const { return compare(Other) < 0; }
+  bool operator>=(const APFixedPoint &Other) const {
+    return compare(Other) >= 0;
+  }
+  bool operator<=(const APFixedPoint &Other) const {
+    return compare(Other) <= 0;
+  }
+
+  static APFixedPoint getMax(const FixedPointSemantics &Sema);
+  static APFixedPoint getMin(const FixedPointSemantics &Sema);
+
+private:
+  llvm::APSInt Val;
+  FixedPointSemantics Sema;
+};
+
+}  // namespace clang
+
+#endif