libc/machine/risc-v: Optimize string routines for misaligned pointers.

libs/libc/machine/risc-v/CMakeLists.txt

@@ -32,6 +32,34 @@ if(CONFIG_RISCV_STRCMP)
   list(APPEND SRCS arch_strcmp.S)
 endif()
 
+if(CONFIG_RISCV_MEMCHR)
+  list(APPEND SRCS arch_memchr.c)
+endif()
+
+if(CONFIG_RISCV_MEMCMP)
+  list(APPEND SRCS arch_memcmp.c)
+endif()
+
+if(CONFIG_RISCV_MEMMOVE)
+  list(APPEND SRCS arch_memmove.c)
+endif()
+
+if(CONFIG_RISCV_STRCPY)
+  list(APPEND SRCS arch_strcpy.c)
+endif()
+
+if(CONFIG_RISCV_STRLCPY)
+  list(APPEND SRCS arch_strlcpy.c)
+endif()
+
+if(CONFIG_RISCV_STRNCMP)
+  list(APPEND SRCS arch_strncmp.c)
+endif()
+
+if(CONFIG_RISCV_STRNLEN)
+  list(APPEND SRCS arch_strnlen.c)
+endif()
+
 if(CONFIG_ARCH_SETJMP_H)
   list(APPEND SRCS arch_setjmp.S)
 endif()

libs/libc/machine/risc-v/Kconfig

@@ -7,9 +7,16 @@ config RISCV_STRING_FUNCTION
 	bool "Enable optimized RISC-V specific string function"
 	default n
 	depends on ARCH_TOOLCHAIN_GNU
+	select RISCV_MEMCHR
+	select RISCV_MEMCMP
 	select RISCV_MEMCPY
+	select RISCV_MEMMOVE
 	select RISCV_MEMSET
 	select RISCV_STRCMP
+	select RISCV_STRCPY
+	select RISCV_STRLCPY
+	select RISCV_STRNCMP
+	select RISCV_STRNLEN
 
 config RISCV_MEMCPY
 	bool "Enable optimized memcpy() for RISC-V"
@@ -34,3 +41,51 @@ config RISCV_STRCMP
 	---help---
 		Enable optimized RISC-V specific strcmp() library function
 
+config RISCV_MEMCHR
+	bool "Enable optimized memchr() for RISC-V"
+	default n
+	select LIBC_ARCH_MEMCHR
+	---help---
+		Enable optimized RISC-V specific memchr() library function
+
+config RISCV_MEMCMP
+	bool "Enable optimized memcmp() for RISC-V"
+	default n
+	select LIBC_ARCH_MEMCMP
+	---help---
+		Enable optimized RISC-V specific memcmp() library function
+
+config RISCV_MEMMOVE
+	bool "Enable optimized memmove() for RISC-V"
+	default n
+	select LIBC_ARCH_MEMMOVE
+	---help---
+		Enable optimized RISC-V specific memmove() library function
+
+config RISCV_STRCPY
+	bool "Enable optimized strcpy() for RISC-V"
+	default n
+	select LIBC_ARCH_STRCPY
+	---help---
+		Enable optimized RISC-V specific strcpy() library function
+
+config RISCV_STRNCMP
+	bool "Enable optimized strncmp() for RISC-V"
+	default n
+	select LIBC_ARCH_STRNCMP
+	---help---
+		Enable optimized RISC-V specific strncmp() library function
+
+config RISCV_STRNLEN
+	bool "Enable optimized strnlen() for RISC-V"
+	default n
+	select LIBC_ARCH_STRNLEN
+	---help---
+		Enable optimized RISC-V specific strnlen() library function
+
+config RISCV_STRLCPY
+	bool "Enable optimized strlcpy() for RISC-V"
+	default n
+	select LIBC_ARCH_STRLCPY
+	---help---
+		Enable optimized RISC-V specific strlcpy() library function

libs/libc/machine/risc-v/Make.defs

@@ -32,6 +32,37 @@ ifeq ($(CONFIG_RISCV_STRCMP),y)
 ASRCS += arch_strcmp.S
 endif
 
+ifeq ($(CONFIG_RISCV_MEMCHR),y)
+CSRCS += arch_memchr.c
+endif
+
+ifeq ($(CONFIG_RISCV_MEMCMP),y)
+CSRCS += arch_memcmp.c
+endif
+
+ifeq ($(CONFIG_RISCV_MEMMOVE),y)
+CSRCS += arch_memmove.c
+endif
+
+
+
+ifeq ($(CONFIG_RISCV_STRCPY),y)
+CSRCS += arch_strcpy.c
+endif
+
+ifeq ($(CONFIG_RISCV_STRLCPY),y)
+CSRCS += arch_strlcpy.c
+endif
+
+ifeq ($(CONFIG_RISCV_STRNCMP),y)
+CSRCS += arch_strncmp.c
+endif
+
+ifeq ($(CONFIG_RISCV_STRNLEN),y)
+CSRCS += arch_strnlen.c
+endif
+
+
 ifeq ($(CONFIG_ARCH_SETJMP_H),y)
 ASRCS += arch_setjmp.S
 endif

libs/libc/machine/risc-v/arch_memchr.c

@@ -0,0 +1,83 @@
+/****************************************************************************
+ * libs/libc/machine/risc-v/arch_memchr.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <string.h>
+
+#include "arch_word.h"
+#include "libc.h"
+
+#ifdef CONFIG_LIBC_ARCH_MEMCHR
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *memchr(FAR const void *s, int c, size_t n)
+{
+  FAR const unsigned char *p = s;
+  unsigned char uc = (unsigned char)c;
+  WORD_T rep = WORD_REPEAT(uc);
+
+  if (n >= 2 * WORD_BYTES)
+    {
+      while (!WORD_ALIGNED(p))
+        {
+          if (n == 0)
+            {
+              return NULL;
+            }
+
+          if (*p == uc)
+            {
+              return (FAR void *)p;
+            }
+
+          p++;
+          n--;
+        }
+
+      while (n >= WORD_BYTES &&
+             !WORD_HASZERO(*(FAR const WORD_T *)p ^ rep))
+        {
+          p += WORD_BYTES;
+          n -= WORD_BYTES;
+        }
+    }
+
+  while (n-- > 0)
+    {
+      if (*p == uc)
+        {
+          return (FAR void *)p;
+        }
+
+      p++;
+    }
+
+  return NULL;
+}
+
+#endif /* CONFIG_LIBC_ARCH_MEMCHR */

libs/libc/machine/risc-v/arch_memcmp.c

@@ -0,0 +1,113 @@
+/****************************************************************************
+ * libs/libc/machine/risc-v/arch_memcmp.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <string.h>
+
+#include "arch_word.h"
+#include "libc.h"
+
+#ifdef CONFIG_LIBC_ARCH_MEMCMP
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int memcmp(FAR const void *s1, FAR const void *s2, size_t n)
+{
+  FAR const unsigned char *a = s1;
+  FAR const unsigned char *b = s2;
+
+  /* Registers at a time when both pointers sit the same distance past a
+   * boundary; a byte head walks them up to it.  Mismatched pointers stay
+   * byte by byte: a shifting compare pays for itself far later than a
+   * shifting copy does.
+   */
+
+  if ((((uintptr_t)a ^ (uintptr_t)b) & (WORD_BYTES - 1)) == 0 &&
+      n >= 2 * WORD_BYTES)
+    {
+      while (!WORD_ALIGNED(a))
+        {
+          if (*a != *b)
+            {
+              return *a - *b;
+            }
+
+          a++;
+          b++;
+          n--;
+        }
+
+      /* Four words a turn, their differences OR-ed together so the
+       * loop carries a single branch.  On a difference, fall out and
+       * let the byte loop find it: it is within four words of here.
+       */
+
+      while (n >= 4 * WORD_BYTES)
+        {
+          WORD_T x = (((FAR const WORD_T *)a)[0] ^
+                      ((FAR const WORD_T *)b)[0]) |
+                     (((FAR const WORD_T *)a)[1] ^
+                      ((FAR const WORD_T *)b)[1]) |
+                     (((FAR const WORD_T *)a)[2] ^
+                      ((FAR const WORD_T *)b)[2]) |
+                     (((FAR const WORD_T *)a)[3] ^
+                      ((FAR const WORD_T *)b)[3]);
+
+          if (x != 0)
+            {
+              break;
+            }
+
+          a += 4 * WORD_BYTES;
+          b += 4 * WORD_BYTES;
+          n -= 4 * WORD_BYTES;
+        }
+
+      while (n >= WORD_BYTES &&
+             *(FAR const WORD_T *)a == *(FAR const WORD_T *)b)
+        {
+          a += WORD_BYTES;
+          b += WORD_BYTES;
+          n -= WORD_BYTES;
+        }
+    }
+
+  while (n-- > 0)
+    {
+      if (*a != *b)
+        {
+          return *a - *b;
+        }
+
+      a++;
+      b++;
+    }
+
+  return 0;
+}
+
+#endif /* CONFIG_LIBC_ARCH_MEMCMP */