[libc-commits] [libc] [libc][stdfix] Implement fixed point bitsfx functions in llvm-libc (PR #116599)

[via libc-commits]

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@@ -0,0 +1,56 @@
+//===-- Utility class to test fixed point to int conversions ----*- 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 "include/llvm-libc-types/stdfix-types.h"
+#include "src/__support/CPP/bit.h"
+#include "src/__support/fixed_point/fx_bits.h"
+
+template <typename T, typename XType>
+class BitsFxTest : 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 quarter = static_cast<T>(0.25);
+  static constexpr T one =
+      (FXRep::INTEGRAL_LEN > 0) ? static_cast<T>(1) : FXRep::MAX();
+  static constexpr T eps = FXRep::EPS();
+  constexpr XType get_one_or_saturated_fraction() {
+    if (FXRep::INTEGRAL_LEN > 0) {
+      return static_cast<XType>(static_cast<XType>(0x1) << FXRep::FRACTION_LEN);
+    } else {
+      return static_cast<XType>(
+          LIBC_NAMESPACE::mask_trailing_ones<typename FXRep::StorageType,
+                                             FXRep::FRACTION_LEN>());
+    }
+  }
+
+public:
+  typedef XType (*BitsFxFunc)(T);
+
+  void test_special_numbers(BitsFxFunc func) {
+    EXPECT_EQ(static_cast<XType>(0), func(zero));
+    EXPECT_EQ(static_cast<XType>(0x1), func(eps));
+    EXPECT_EQ(static_cast<XType>(static_cast<XType>(0x1)
+                                 << (FXRep::FRACTION_LEN - 1)),
+              func(half));
+    // Occupy the bit to the left of the fixed point for Accum types
+    // Saturate fraction portion for Fract types
+    EXPECT_EQ(get_one_or_saturated_fraction(), func(one));
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PiJoules wrote:

This is me being pedantic, but could you also add some test cases for more boring, non-corner case numbers? Values like `5`, `16`, `-10.25`, etc.

https://github.com/llvm/llvm-project/pull/116599