Added set_bits<> to bitutils.

This allows us to get a constant with the given bits set at
compile-time. This is needed for a future patch for HexFloat.

CMakeLists.txt

@@ -102,7 +102,7 @@ include_directories(
 
 set(SPIRV_SOURCES
   ${CMAKE_CURRENT_SOURCE_DIR}/include/libspirv/libspirv.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/util/bitwisecast.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/include/util/bitutils.h
   ${CMAKE_CURRENT_SOURCE_DIR}/source/binary.h
   ${CMAKE_CURRENT_SOURCE_DIR}/source/diagnostic.h
   ${CMAKE_CURRENT_SOURCE_DIR}/source/ext_inst.h

include/util/bitutils.h

@@ -0,0 +1,89 @@
+// Copyright (c) 2015 The Khronos Group Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and/or associated documentation files (the
+// "Materials"), to deal in the Materials without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Materials, and to
+// permit persons to whom the Materials are furnished to do so, subject to
+// the following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Materials.
+//
+// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
+// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
+// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
+//    https://www.khronos.org/registry/
+//
+// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
+
+#ifndef _LIBSPIRV_UTIL_BITUTILS_H_
+#define _LIBSPIRV_UTIL_BITUTILS_H_
+
+#include <cstring>
+
+namespace spvutils {
+
+// Performs a bitwise copy of source to the destination type Dest.
+template <typename Dest, typename Src>
+Dest BitwiseCast(Src source) {
+  Dest dest;
+  static_assert(sizeof(source) == sizeof(dest),
+                "BitwiseCast: Source and destination must have the same size");
+  std::memcpy(&dest, &source, sizeof(dest));
+  return dest;
+}
+
+// SetBits<T, First, Last> returns an integer of type <T> with the bits
+// between First and Last inclusive set and all other bits 0. This is indexed
+// from left to right So SetBits<unsigned long, 0, 1> would have the leftmost
+// two bits set.
+template<typename T, T First = 0, T Last = 0>
+struct SetBits {
+  static_assert(First < Last, "The first bit must be before the last bit");
+  const static T get = (T(1) << ((sizeof(T) * 8) - First - 1)) |
+                       SetBits<T, First + 1, Last>::get;
+};
+
+template<typename T, T Last>
+struct SetBits<T, Last, Last> {
+  const static T get = T(1) << ((sizeof(T) * 8) - Last - 1);
+};
+
+// This is all compile-time so we can put our tests right here.
+static_assert(SetBits<uint32_t, 0, 0>::get == uint32_t(0x80000000),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 0, 1>::get == uint32_t(0xc0000000),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 1, 2>::get == uint32_t(0x60000000),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 31, 31>::get == uint32_t(0x00000001),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 31, 32>::get == uint32_t(0x00000001),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 30, 31>::get == uint32_t(0x00000003),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 0, 31>::get == uint32_t(0xFFFFFFFF),
+              "SetBits failed");
+static_assert(SetBits<uint32_t, 16, 31>::get == uint32_t(0x0000FFFF),
+              "SetBits failed");
+
+static_assert(SetBits<uint64_t, 0, 0>::get == uint64_t(0x8000000000000000LL),
+              "SetBits failed");
+static_assert(SetBits<uint64_t, 0, 1>::get == uint64_t(0xc000000000000000LL),
+              "SetBits failed");
+static_assert(SetBits<uint64_t, 32, 32>::get == uint64_t(0x0000000080000000LL),
+              "SetBits failed");
+static_assert(SetBits<uint64_t, 16, 31>::get == uint64_t(0x0000FFFF00000000LL),
+              "SetBits failed");
+
+}  // namespace spvutils
+
+#endif

include/util/bitwisecast.h

@@ -1,46 +0,0 @@
-// Copyright (c) 2015 The Khronos Group Inc.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a
-// copy of this software and/or associated documentation files (the
-// "Materials"), to deal in the Materials without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Materials, and to
-// permit persons to whom the Materials are furnished to do so, subject to
-// the following conditions:
-//
-// The above copyright notice and this permission notice shall be included
-// in all copies or substantial portions of the Materials.
-//
-// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
-// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
-// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
-//    https://www.khronos.org/registry/
-//
-// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
-
-#ifndef _LIBSPIRV_UTIL_BITWISECAST_H_
-#define _LIBSPIRV_UTIL_BITWISECAST_H_
-
-#include <cstring>
-
-namespace spvutils {
-
-// Performs a bitwise copy of source to the destination type Dest.
-template <typename Dest, typename Src>
-Dest BitwiseCast(Src source) {
-  Dest dest;
-  static_assert(sizeof(source) == sizeof(dest),
-                "BitwiseCast: Source and destination must have the same size");
-  std::memcpy(&dest, &source, sizeof(dest));
-  return dest;
-}
-
-}  // namespace spvutils
-
-#endif

source/text.cpp

@@ -46,7 +46,7 @@
 #include "opcode.h"
 #include "operand.h"
 #include "text_handler.h"
-#include "util/bitwisecast.h"
+#include "util/bitutils.h"
 
 bool spvIsValidIDCharacter(const char value) {
   return value == '_' || 0 != ::isalnum(value);

source/text_handler.cpp

@@ -37,7 +37,7 @@
 #include "instruction.h"
 #include "opcode.h"
 #include "text.h"
-#include "util/bitwisecast.h"
+#include "util/bitutils.h"
 
 namespace {
 

test/ImmediateInt.cpp

@@ -31,7 +31,7 @@
 #include <gmock/gmock.h>
 
 #include "TestFixture.h"
-#include "util/bitwisecast.h"
+#include "util/bitutils.h"
 
 namespace {
 

test/TextToBinary.cpp

@@ -26,6 +26,8 @@
 
 #include "TestFixture.h"
 #include "UnitSPIRV.h"
+#include "util/bitutils.h"
+
 #include <algorithm>
 #include <utility>
 #include <vector>

test/UnitSPIRV.h

@@ -60,7 +60,7 @@ enum {
 };
 
 // TODO(dneto): Using a union this way relies on undefined behaviour.
-// Replace this with uses of BitwiseCast from source/bitwisecast.h
+// Replace this with uses of BitwiseCast from util/bitutils.h
 static const union {
   unsigned char bytes[4];
   uint32_t value;