[libc][math][c23] Add scalbnf16 C23 math function

Author: overmighty

libc/config/linux/aarch64/entrypoints.txt

@@ -540,6 +540,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.rintf16
     libc.src.math.roundf16
     libc.src.math.roundevenf16
+    libc.src.math.scalbnf16
     libc.src.math.truncf16
     libc.src.math.ufromfpf16
     libc.src.math.ufromfpxf16

libc/config/linux/x86_64/entrypoints.txt

@@ -570,6 +570,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
     libc.src.math.rintf16
     libc.src.math.roundf16
     libc.src.math.roundevenf16
+    libc.src.math.scalbnf16
     libc.src.math.truncf16
     libc.src.math.ufromfpf16
     libc.src.math.ufromfpxf16

libc/docs/math/index.rst

@@ -208,7 +208,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | roundeven        | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.9.8               | F.10.6.8                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| scalbn           | |check|          | |check|         | |check|                |                      | |check|                | 7.12.6.19              | F.10.3.19                  |
+| scalbn           | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.6.19              | F.10.3.19                  |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | trunc            | |check|          | |check|         | |check|                | |check|              | |check|                | 7.12.9.9               | F.10.6.9                   |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

libc/spec/stdc.td

@@ -696,6 +696,7 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"scalbn", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<IntType>]>,
           FunctionSpec<"scalbnf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<IntType>]>,
           FunctionSpec<"scalbnl", RetValSpec<LongDoubleType>, [ArgSpec<LongDoubleType>, ArgSpec<IntType>]>,
+          GuardedFunctionSpec<"scalbnf16", RetValSpec<Float16Type>, [ArgSpec<Float16Type>, ArgSpec<IntType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"scalbnf128", RetValSpec<Float128Type>, [ArgSpec<Float128Type>, ArgSpec<IntType>], "LIBC_TYPES_HAS_FLOAT128">,
 
           FunctionSpec<"nanf", RetValSpec<FloatType>, [ArgSpec<ConstCharPtr>]>,

libc/src/math/CMakeLists.txt

@@ -343,6 +343,7 @@ add_math_entrypoint_object(roundevenf128)
 add_math_entrypoint_object(scalbn)
 add_math_entrypoint_object(scalbnf)
 add_math_entrypoint_object(scalbnl)
+add_math_entrypoint_object(scalbnf16)
 add_math_entrypoint_object(scalbnf128)
 
 add_math_entrypoint_object(sincos)

libc/src/math/generic/CMakeLists.txt

@@ -3527,6 +3527,20 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  scalbnf16
+  SRCS
+    scalbnf16.cpp
+  HDRS
+    ../scalbnf16.h
+  DEPENDS
+    libc.hdr.float_macros
+    libc.src.__support.macros.properties.types
+    libc.src.__support.FPUtil.manipulation_functions
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   scalbnf128
   SRCS

libc/src/math/generic/scalbnf16.cpp

@@ -0,0 +1,25 @@
+//===-- Implementation of scalbnf16 function ------------------------------===//
+//
+// 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/math/scalbnf16.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/common.h"
+
+#include "hdr/float_macros.h"
+
+#if FLT_RADIX != 2
+#error "FLT_RADIX != 2 is not supported."
+#endif
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float16, scalbnf16, (float16 x, int n)) {
+  return fputil::ldexp(x, n);
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/math/scalbnf16.h

@@ -0,0 +1,20 @@
+//===-- Implementation header for scalbnf16 ---------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_MATH_SCALBNF16_H
+#define LLVM_LIBC_SRC_MATH_SCALBNF16_H
+
+#include "src/__support/macros/properties/types.h"
+
+namespace LIBC_NAMESPACE {
+
+float16 scalbnf16(float16 x, int n);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_SCALBNF16_H

libc/test/src/math/smoke/CMakeLists.txt

@@ -3490,6 +3490,19 @@ add_fp_unittest(
     libc.src.__support.FPUtil.fp_bits
 )
 
+add_fp_unittest(
+  scalbnf16_test
+  SUITE
+    libc-math-smoke-tests
+  SRCS
+    scalbnf16_test.cpp
+  HDRS
+    ScalbnTest.h
+  DEPENDS
+    libc.src.math.scalbnf16
+    libc.src.__support.FPUtil.fp_bits
+)
+
 add_fp_unittest(
   scalbnf128_test
   SUITE

libc/test/src/math/smoke/scalbnf16_test.cpp

@@ -0,0 +1,13 @@
+//===-- Unittests for scalbnf16 -------------------------------------------===//
+//
+// 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 "ScalbnTest.h"
+
+#include "src/math/scalbnf16.h"
+
+LIST_SCALBN_TESTS(float16, LIBC_NAMESPACE::scalbnf16)