libc/string: replace __builtin_ffsl with inline function

In the gcc-riscv compiler, __builtin_ffs will call ffs, and calling __builtin_ffs in ffs will cause recursion

Change ffs to an inline function, and compile ffs implemented by nuttx by default.
Only call the implementation of nuttx when the compiler cannot provide an ffs implementation.

Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>

include/strings.h

@@ -73,16 +73,77 @@ extern "C"
  * Public Function Prototypes
  ****************************************************************************/
 
+#ifdef CONFIG_HAVE_BUILTIN_FFS
+static inline_function int ffs(int j)
+{
+  return __builtin_ffs(j);
+}
+#elif defined (CONFIG_HAVE_BUILTIN_CTZ)
+static inline_function int ffs(int j)
+{
+  return __builtin_ctz(j) + 1;
+}
+#else
 int ffs(int j);
-int ffsl(long j);
-#ifdef CONFIG_HAVE_LONG_LONG
-int ffsll(long long j);
 #endif
 
-int fls(int j);
+#ifdef CONFIG_HAVE_BUILTIN_FFSL
-int flsl(long j);
+static inline_function int ffsl(long j)
+{
+  return __builtin_ffsl(j);
+}
+#elif defined (CONFIG_HAVE_BUILTIN_CTZ)
+static inline_function int ffsl(long j)
+{
+  return __builtin_ctzl(j) + 1;
+}
+#else
+int ffsl(long j);
+#endif
+
 #ifdef CONFIG_HAVE_LONG_LONG
+#  ifdef CONFIG_HAVE_BUILTIN_FFSLL
+static inline_function int ffsll(long long j)
+{
+    return __builtin_ffsll(j);
+}
+#  elif defined (CONFIG_HAVE_BUILTIN_CTZ)
+static inline_function int ffsll(long long j)
+{
+    return __builtin_ctzll(j) + 1;
+}
+#  else
+int ffsll(long long j);
+#  endif
+#endif
+
+#ifdef CONFIG_HAVE_BUILTIN_CLZ
+static inline_function int fls(int j)
+{
+  return (8 * sizeof(int)) - __builtin_clz(j);
+}
+#else
+int fls(int j);
+#endif
+
+#ifdef CONFIG_HAVE_BUILTIN_CLZ
+static inline_function int flsl(long j)
+{
+  return (8 * sizeof(long)) - __builtin_clzl(j);
+}
+#else
+int flsl(long j);
+#endif
+
+#ifdef CONFIG_HAVE_LONG_LONG
+#  ifdef CONFIG_HAVE_BUILTIN_CLZ
+static inline_function int flsll(long long j)
+{
+  return (8 * sizeof(long long)) - __builtin_clzll(j);
+}
+#  else
 int flsll(long long j);
+#  endif
 #endif
 
 unsigned int popcount(unsigned int j);

libs/libc/string/lib_ffs.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -55,13 +48,6 @@ int ffs(int j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_FFS
-      ret = __builtin_ffs(j);
-#elif defined (CONFIG_HAVE_BUILTIN_CTZ)
-      /* Count trailing zeros function can be used to implement ffs. */
-
-      ret = __builtin_ctz(j) + 1;
-#else
       unsigned int value = (unsigned int)j;
       int bitno;
 
@@ -73,7 +59,6 @@ int ffs(int j)
               break;
             }
         }
-#endif
     }
 
   return ret;

libs/libc/string/lib_ffsl.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -55,13 +48,6 @@ int ffsl(long j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_FFSL
-      ret = __builtin_ffsl(j);
-#elif defined (CONFIG_HAVE_BUILTIN_CTZ)
-      /* Count trailing zeros function can be used to implement ffs. */
-
-      ret = __builtin_ctzl(j) + 1;
-#else
       unsigned long value = (unsigned long)j;
       int bitno;
 
@@ -73,7 +59,6 @@ int ffsl(long j)
               break;
             }
         }
-#endif
     }
 
   return ret;

libs/libc/string/lib_ffsll.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -57,13 +50,6 @@ int ffsll(long long j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_FFSLL
-      ret = __builtin_ffsll(j);
-#elif defined (CONFIG_HAVE_BUILTIN_CTZ)
-      /* Count trailing zeros function can be used to implement ffs. */
-
-      ret = __builtin_ctzll(j) + 1;
-#else
       unsigned long long value = (unsigned long long)j;
       int bitno;
 
@@ -75,10 +61,8 @@ int ffsll(long long j)
               break;
             }
         }
-#endif
     }
 
   return ret;
 }
-
 #endif

libs/libc/string/lib_fls.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -55,11 +48,6 @@ int fls(int j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_CLZ
-      /* Count leading zeros function can be used to implement fls. */
-
-      ret = NBITS - __builtin_clz(j);
-#else
       unsigned int value = (unsigned int)j;
       int bitno;
 
@@ -71,7 +59,6 @@ int fls(int j)
               break;
             }
         }
-#endif
     }
 
   return ret;

libs/libc/string/lib_flsl.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -55,11 +48,6 @@ int flsl(long j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_CLZ
-      /* Count leading zeros function can be used to implement fls. */
-
-      ret = NBITS - __builtin_clzl(j);
-#else
       unsigned long value = (unsigned long)j;
       int bitno;
 
@@ -71,7 +59,6 @@ int flsl(long j)
               break;
             }
         }
-#endif
     }
 
   return ret;

libs/libc/string/lib_flsll.c

@@ -18,13 +18,6 @@
  *
  ****************************************************************************/
 
-/****************************************************************************
- * Included Files
- ****************************************************************************/
-
-#include <nuttx/compiler.h>
-#include <strings.h>
-
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -57,11 +50,6 @@ int flsll(long long j)
 
   if (j != 0)
     {
-#ifdef CONFIG_HAVE_BUILTIN_CLZ
-      /* Count leading zeros function can be used to implement fls. */
-
-      ret = NBITS - __builtin_clzll(j);
-#else
       unsigned long long value = (unsigned long long)j;
       int bitno;
 
@@ -73,10 +61,8 @@ int flsll(long long j)
               break;
             }
         }
-#endif
     }
 
   return ret;
 }
-
 #endif