Implement rbits and add a test fixture

Author: smallp-o-p

libc/src/stdfix/rbits.cpp

@@ -0,0 +1,13 @@
+#include "rbits.h"
+
+#include "src/__support/common.h"
+#include "src/__support/fixed_point/fx_bits.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(fract, rbits, (int_r_t x)) {
+    return fixed_point::fxbits<fract, int_r_t>(x);
+}
+
+}

libc/src/stdfix/rbits.h

@@ -0,0 +1,12 @@
+#ifndef LLVM_LIBC_SRC_STDFIX_HRBITS_H
+#define LLVM_LIBC_SRC_STDFIX_HRBITS_H
+    
+#include "include/llvm-libc-macros/stdfix-macros.h"
+#include "src/__support/macros/config.h"
+namespace LIBC_NAMESPACE_DECL {
+
+fract rbits(int_r_t x); 
+
+}
+
+#endif 

libc/test/src/stdfix/CMakeLists.txt

@@ -59,6 +59,23 @@ foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
   )
 endforeach()
 
+foreach(prefix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
+  add_libc_test(
+    ${prefix}bits_test
+    SUITE
+      libc-stdfix-tests
+    HDRS
+      FxbitsTest.h
+    SRCS
+      ${prefix}bits_test.cpp
+    COMPILE_OPTIONS
+      -O3
+    DEPENDS
+      libc.src.stdfix.${prefix}bits
+      libc.src.__support.fixed_point.fx_bits
+  )
+endforeach()
+
 add_libc_test(
   uhksqrtus_test
   SUITE

libc/test/src/stdfix/FxbitsTest.h

@@ -0,0 +1,37 @@
+//===-- Utility class to test fxbits -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "test/UnitTest/Test.h"
+#include "src/__support/fixed_point/fx_rep.h"
+
+template <typename T, typename XType> class FxbitsTest : public LIBC_NAMESPACE::testing::Test {
+    using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<T>;
+    static constexpr T zero = FXRep::ZERO();
+    static constexpr T min = FXRep::MIN();
+    static constexpr T max = FXRep::MAX();
+    static constexpr T half = static_cast<T>(0.5);
+    static constexpr T neg_half = static_cast<T>(-0.5);
+    static constexpr T one =
+        (FXRep::INTEGRAL_LEN > 0) ? static_cast<T>(1) : FXRep::MAX();
+    static constexpr T neg_one = static_cast<T>(-1);
+    static constexpr T eps = FXRep::EPS();
+
+public:
+    typedef T (*FxbitsFunc)(XType); 
+
+    void testSpecialNumbers(FxbitsFunc func) {
+        EXPECT_EQ(zero, func(0));
+        EXPECT_EQ(half, func((XType) (0b1 << (FXRep::FRACTION_LEN - 1)))); // 0.1000...b
+    }
+};
+
+
+#define LIST_FXBITS_TEST(T, XType, func)                                        \
+    using LlvmLibcFxbitsTest = FxbitsTest<T, XType>;                            \  
+    TEST_F(LlvmLibcFxbitsTest, SpecialNumbers) { testSpecialNumbers(&func); }   \ 
+    static_assert(true, "Require semicolon.")

libc/test/src/stdfix/rbits_test.cpp

@@ -0,0 +1,7 @@
+
+#include "FxbitsTest.h"
+
+#include "src/stdfix/rbits.h"
+
+LIST_FXBITS_TEST(fract, int_r_t, LIBC_NAMESPACE::rbits);
+