[libc-commits] [libc] [libc][stdfix] Implement fixed point bitsfx functions in llvm libc (PR #128413)

[Krishna Pandey via libc-commits]

================
@@ -0,0 +1,94 @@
+//===-- Utility class to test bitsfx functions ------------------*- 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 BitsFxTest : public LIBC_NAMESPACE::testing::Test {
+
+  using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<T>;
+  static constexpr T zero = FXRep::ZERO();
+  static constexpr T max = FXRep::MAX();
+  static constexpr T min = FXRep::MIN();
+  static constexpr T one_half = FXRep::ONE_HALF();
+  static constexpr T one_fourth = FXRep::ONE_FOURTH();
+  static constexpr T eps = FXRep::EPS();
+
+  static constexpr T zero_point_six_eight_seven_five_t = 0.6875;
+
+  static constexpr T negative_zero_point_six_eight_seven_five_t = -0.6875;
+
+  // an arbitrarily chosen special number
+  static constexpr T special_num_t = 10.71875;
+
+  static constexpr T negative_special_num_t = -10.71875;
+
+public:
+  typedef XType (*BitsFxFunc)(T);
+
+  void testSpecialNumbers(BitsFxFunc func) {
+    EXPECT_EQ(static_cast<XType>(0), func(zero));
+    EXPECT_EQ(static_cast<XType>(1ULL << (FXRep::FRACTION_LEN - 1)),
+              func(one_half));
+    EXPECT_EQ(static_cast<XType>(1ULL << (FXRep::FRACTION_LEN - 2)),
+              func(one_fourth));
+    EXPECT_EQ(static_cast<XType>(1), func(eps));
+
+    // (0.6875)_10 = (0.1011)_2
+    EXPECT_EQ(static_cast<XType>(11ULL << (FXRep::FRACTION_LEN - 4)),
+              func(zero_point_six_eight_seven_five_t));
+
+    if constexpr (FXRep::SIGN_LEN > 0)
+      EXPECT_EQ(static_cast<XType>(-(11ULL << (FXRep::FRACTION_LEN - 4))),
+                func(negative_zero_point_six_eight_seven_five_t));
+
+    if constexpr (FXRep::INTEGRAL_LEN > 0) {
+      if (static_cast<int>(max) >= 11)
+        switch (FXRep::FRACTION_LEN) {
+        case 7:
+          EXPECT_EQ(static_cast<XType>(1372), func(special_num_t));
+          break;
+        case 15:
+          EXPECT_EQ(static_cast<XType>(351232), func(special_num_t));
+          break;
+        case 23:
+          EXPECT_EQ(static_cast<XType>(89915392), func(special_num_t));
+          break;
+        default:
+          break;
+        }
+    }
+
+    if constexpr (FXRep::SIGN_LEN > 0 && FXRep::INTEGRAL_LEN > 0) {
+      if (static_cast<int>(min) <= -11)
+        switch (FXRep::FRACTION_LEN) {
----------------
krishna2803 wrote:

updated here:

https://github.com/llvm/llvm-project/blob/2f9b642f71f63973e0c3ae65fbdd7bd19dd0533b/libc/test/src/stdfix/BitsFxTest.h#L63-L70

also refactored the tests for signed accum types to share the common `if` for `FXRep::INTEGRAL_LEN > 0`

https://github.com/llvm/llvm-project/pull/128413