[libc-commits] [libc] [libc][stdfix] Implement fxdivi functions (rdivi) (PR #154914)

[via libc-commits]

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@@ -0,0 +1,65 @@
+//===-- Utility class to test fxdivi 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 "src/__support/CPP/type_traits.h"
+#include "src/__support/fixed_point/fx_bits.h"
+#include "src/__support/fixed_point/fx_rep.h"
+#include "test/UnitTest/Test.h"
+
+template <typename XType> XType get_epsilon() = delete;
+template <> fract get_epsilon() { return FRACT_EPSILON; }
+template <> unsigned fract get_epsilon() { return UFRACT_EPSILON; }
+template <> long fract get_epsilon() { return LFRACT_EPSILON; }
+
+template <typename XType>
+class DivITest : public LIBC_NAMESPACE::testing::Test {
+  using FXRep = LIBC_NAMESPACE::fixed_point::FXRep<XType>;
+  using FXBits = LIBC_NAMESPACE::fixed_point::FXBits<XType>;
+
+public:
+  typedef XType (*DivIFunc)(int, int);
+
+  void testBasic(DivIFunc func) {
+    XType epsilon = get_epsilon<XType>();
+    EXPECT_LT((func(2, 3) - 0.666656494140625r), epsilon);
+    EXPECT_LT((func(3, 4) - 0.75r), epsilon);
+    EXPECT_LT((func(1043, 2764) - 0.3773516643r), epsilon);
+    EXPECT_LT((func(60000, 720293) - 0.08329943509r), epsilon);
+
+    EXPECT_EQ(func(128, 256), 0.5r);
+    EXPECT_EQ(func(1, 2), 0.5r);
+    EXPECT_EQ(func(1, 4), 0.25r);
+    EXPECT_EQ(func(1, 8), 0.125r);
+    EXPECT_EQ(func(1, 16), 0.0625r);
+
+    EXPECT_EQ(func(-1, 2), -0.5r);
+    EXPECT_EQ(func(1, -4), -0.25r);
+    EXPECT_EQ(func(-1, 8), -0.125r);
+    EXPECT_EQ(func(1, -16), -0.0625r);
+  }
+
+  void testSpecial(DivIFunc func) {
+    EXPECT_EQ(func(0,10), 0.r);
+    EXPECT_EQ(func(0,-10), 0.r);
+    EXPECT_EQ(func(-32768,32768), FRACT_MIN);
+    EXPECT_EQ(func(32767,32768), FRACT_MAX);  
+    EXPECT_EQ(func(INT_MAX,INT_MAX), 1.0r);
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PiJoules wrote:

Tangentially, it also might be good to add some tests which would trigger the saturated overflow case. So maybe some integral values which would resolve to either less than zero or greater than or equal to one which would saturate to zero and `FRACT_MAX`.

https://github.com/llvm/llvm-project/pull/154914