[libc] implement countlsfx

libc/config/baremetal/arm/entrypoints.txt

@@ -427,6 +427,18 @@ set(TARGET_LIBM_ENTRYPOINTS
 if(LIBC_COMPILER_HAS_FIXED_POINT)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # stdfix.h _Fract and _Accum entrypoints
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsur
     libc.src.stdfix.abshk
     libc.src.stdfix.abshr
     libc.src.stdfix.absk

libc/config/baremetal/riscv/entrypoints.txt

@@ -422,6 +422,18 @@ set(TARGET_LIBM_ENTRYPOINTS
 if(LIBC_COMPILER_HAS_FIXED_POINT)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # stdfix.h _Fract and _Accum entrypoints
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsur
     libc.src.stdfix.abshk
     libc.src.stdfix.abshr
     libc.src.stdfix.absk

libc/config/linux/riscv/entrypoints.txt

@@ -677,6 +677,18 @@ endif()
 if(LIBC_COMPILER_HAS_FIXED_POINT)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # stdfix.h _Fract and _Accum entrypoints
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsur
     libc.src.stdfix.abshk
     libc.src.stdfix.abshr
     libc.src.stdfix.absk

libc/config/linux/x86_64/entrypoints.txt

@@ -780,6 +780,18 @@ endif()
 if(LIBC_COMPILER_HAS_FIXED_POINT)
   list(APPEND TARGET_LIBM_ENTRYPOINTS
     # stdfix.h _Fract and _Accum entrypoints
+    libc.src.stdfix.countlshk
+    libc.src.stdfix.countlshr
+    libc.src.stdfix.countlsk
+    libc.src.stdfix.countlslk
+    libc.src.stdfix.countlslr
+    libc.src.stdfix.countlsr
+    libc.src.stdfix.countlsuhk
+    libc.src.stdfix.countlsuhr
+    libc.src.stdfix.countlsuk
+    libc.src.stdfix.countlsulk
+    libc.src.stdfix.countlsulr
+    libc.src.stdfix.countlsur
     libc.src.stdfix.abshk
     libc.src.stdfix.abshr
     libc.src.stdfix.absk

libc/spec/stdc_ext.td

@@ -24,6 +24,23 @@ def StdcExt : StandardSpec<"stdc_ext"> {
       [],  // types
       [],  // enums
       [    // functions
+
+          GuardedFunctionSpec<"countlshr", RetValSpec<ShortFractType>, [ArgSpec<ShortFractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsr", RetValSpec<FractType>, [ArgSpec<FractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlslr", RetValSpec<LongFractType>, [ArgSpec<LongFractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+          GuardedFunctionSpec<"countlshk", RetValSpec<ShortAccumType>, [ArgSpec<ShortAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsk", RetValSpec<AccumType>, [ArgSpec<AccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlslk", RetValSpec<LongAccumType>, [ArgSpec<LongAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+          GuardedFunctionSpec<"countlsuhr", RetValSpec<UnsignedShortFractType>, [ArgSpec<UnsignedShortFractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsur", RetValSpec<UnsignedFractType>, [ArgSpec<UnsignedFractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsulr", RetValSpec<UnsignedLongFractType>, [ArgSpec<UnsignedLongFractType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
+          GuardedFunctionSpec<"countlsuhk", RetValSpec<UnsignedShortAccumType>, [ArgSpec<UnsignedShortAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsuk", RetValSpec<UnsignedAccumType>, [ArgSpec<UnsignedAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+          GuardedFunctionSpec<"countlsulk", RetValSpec<UnsignedLongAccumType>, [ArgSpec<UnsignedLongAccumType>, ArgSpec<IntType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
+
           GuardedFunctionSpec<"abshr", RetValSpec<ShortFractType>, [ArgSpec<ShortFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
           GuardedFunctionSpec<"absr", RetValSpec<FractType>, [ArgSpec<FractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,
           GuardedFunctionSpec<"abslr", RetValSpec<LongFractType>, [ArgSpec<LongFractType>], "LIBC_COMPILER_HAS_FIXED_POINT">,

libc/src/__support/fixed_point/CMakeLists.txt

@@ -20,6 +20,7 @@ add_header_library(
     libc.src.__support.CPP.type_traits
     libc.src.__support.CPP.bit
     libc.src.__support.math_extras
+    libc.src.__support.CPP.limits
 )
 
 add_header_library(

libc/src/__support/fixed_point/fx_bits.h

@@ -11,8 +11,9 @@
 
 #include "include/llvm-libc-macros/stdfix-macros.h"
 #include "src/__support/CPP/bit.h"
+#include "src/__support/CPP/limits.h" // numeric_limits
 #include "src/__support/CPP/type_traits.h"
-#include "src/__support/macros/attributes.h"   // LIBC_INLINE
+#include "src/__support/macros/attributes.h" // LIBC_INLINE
 #include "src/__support/macros/config.h"
 #include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
 #include "src/__support/math_extras.h"
@@ -66,6 +67,23 @@ template <typename T> struct FXBits {
     }
   }
 
+  // Clause 6.2.6.3 of ISO/IEC TR 18037 defines the value bits of a fixed-point
+  // type to include the integral and fraction bits but not padding nor sign
+  // bits.
+  //
+  // This function returns the value bits, right-aligned, as an unsigned integer
+  // type which is at least large enough to hold them all.
+  //
+  // Note the integral and fraction bits are contiguous. The rightmost bits in
+  // the returned value are the fraciton bits, then immediately left of those
+  // are the integral bits.
+  //
+  // Any left-padding in the return value is guaranteed to be zero.
+  LIBC_INLINE constexpr StorageType get_value_bits() {
+    constexpr StorageType VALUE_MASK = INTEGRAL_MASK | FRACTION_MASK;
+    return (value & VALUE_MASK) >> FRACTION_OFFSET;
+  }
+
   LIBC_INLINE constexpr StorageType get_fraction() {
     return (value & FRACTION_MASK) >> FRACTION_OFFSET;
   }
@@ -142,6 +160,25 @@ template <typename T> LIBC_INLINE constexpr T abs(T x) {
   }
 }
 
+template <typename T>
+LIBC_INLINE constexpr cpp::enable_if_t<cpp::is_fixed_point_v<T>, int>
+countls(T x) {
+  using FXRep = FXRep<T>;
+  using BitType = typename FXRep::StorageType;
+  constexpr int CONTAIN_LEN = cpp::numeric_limits<BitType>::digits;
+  constexpr int PADDING_LEN = CONTAIN_LEN - FXRep::VALUE_LEN;
+
+  if constexpr (FXRep::SIGN_LEN != 0) {
+    if (x < 0) {
+      x = abs(x + FXRep::EPS());
+    }
+  }
+
+  FXBits<T> fxbits(x);
+  BitType value_bits = fxbits.get_value_bits();
+  return cpp::countl_zero(value_bits) - PADDING_LEN;
+}
+
 // Round-to-nearest, tie-to-(+Inf)
 template <typename T> LIBC_INLINE constexpr T round(T x, int n) {
   using FXRep = FXRep<T>;

libc/src/__support/fixed_point/fx_rep.h

@@ -45,6 +45,7 @@ template <> struct FXRep<short fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = SFRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return SFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return SFRACT_MAX; }
@@ -65,6 +66,7 @@ template <> struct FXRep<unsigned short fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = USFRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return USFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return USFRACT_MAX; }
@@ -85,6 +87,7 @@ template <> struct FXRep<fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = FRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return FRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return FRACT_MAX; }
@@ -105,6 +108,7 @@ template <> struct FXRep<unsigned fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = UFRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return UFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return UFRACT_MAX; }
@@ -125,6 +129,7 @@ template <> struct FXRep<long fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = LFRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return LFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return LFRACT_MAX; }
@@ -145,6 +150,7 @@ template <> struct FXRep<unsigned long fract> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ULFRACT_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ULFRACT_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ULFRACT_MAX; }
@@ -165,6 +171,7 @@ template <> struct FXRep<short accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = SACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return SACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return SACCUM_MAX; }
@@ -185,6 +192,7 @@ template <> struct FXRep<unsigned short accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = USACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return USACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return USACCUM_MAX; }
@@ -205,6 +213,7 @@ template <> struct FXRep<accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ACCUM_MAX; }
@@ -225,6 +234,7 @@ template <> struct FXRep<unsigned accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = UACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return UACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return UACCUM_MAX; }
@@ -245,6 +255,7 @@ template <> struct FXRep<long accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = LACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return LACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return LACCUM_MAX; }
@@ -265,6 +276,7 @@ template <> struct FXRep<unsigned long accum> {
   LIBC_INLINE_VAR static constexpr int FRACTION_LEN = ULACCUM_FBIT;
   LIBC_INLINE_VAR static constexpr int TOTAL_LEN =
       SIGN_LEN + INTEGRAL_LEN + FRACTION_LEN;
+  LIBC_INLINE_VAR static constexpr int VALUE_LEN = INTEGRAL_LEN + FRACTION_LEN;
 
   LIBC_INLINE static constexpr Type MIN() { return ULACCUM_MIN; }
   LIBC_INLINE static constexpr Type MAX() { return ULACCUM_MAX; }

libc/src/stdfix/CMakeLists.txt

@@ -2,6 +2,20 @@ if(NOT LIBC_COMPILER_HAS_FIXED_POINT)
   return()
 endif()
 
+foreach(suffix IN ITEMS hr r lr hk k lk uhr ur ulr uhk uk ulk)
+  add_entrypoint_object(
+    countls${suffix}
+    HDRS
+      countls${suffix}.h
+    SRCS
+      countls${suffix}.cpp
+    COMPILE_OPTIONS
+      -O3
+    DEPENDS
+      libc.src.__support.fixed_point.fx_bits
+  )
+endforeach()
+
 foreach(suffix IN ITEMS hr r lr hk k lk)
   add_entrypoint_object(
     abs${suffix}

libc/src/stdfix/countlshk.cpp

@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "countlshk.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(int, countlshk, (short accum x)) {
+  return fixed_point::countls(x);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/stdfix/countlshk.h

@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_STDFIX_COUNTLSHK_H
+#define LLVM_LIBC_SRC_STDFIX_COUNTLSHK_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int countlshk(short accum x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDFIX_COUNTLSHK_H

libc/src/stdfix/countlshr.cpp

@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "countlshr.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(int, countlshr, (short fract x)) {
+  return fixed_point::countls(x);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/stdfix/countlshr.h

@@ -0,0 +1,21 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_STDFIX_COUNTLSHR_H
+#define LLVM_LIBC_SRC_STDFIX_COUNTLSHR_H
+
+#include "include/llvm-libc-macros/stdfix-macros.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int countlshr(short fract x);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_STDFIX_COUNTLSHR_H

libc/src/stdfix/countlsk.cpp

@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "countlsk.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(int, countlsk, (accum x)) { return fixed_point::countls(x); }
+
+} // namespace LIBC_NAMESPACE_DECL