[libc] implement extension standard C functions (#6044)

* implement extension standard C functions

1 files changed, 223 insertions, 0 deletions

diff --git a/components/libc/compilers/common/cstring.c b/components/libc/compilers/common/cstring.c
new file mode 100644
index 0000000000..dec1213d79
--- /dev/null
+++ b/components/libc/compilers/common/cstring.c
@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2006-2022, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2022-01-12     Meco Man     The first version.
+ */
+
+#include "posix/string.h"
+#include <ctype.h>
+#include <rtthread.h>
+#include <stdlib.h>
+
+/**
+ * @brief erases the data in the n bytes of the memory starting at the
+ *        location pointed to by s, by writing zeros (bytes containing '\0') to that area.
+ *
+ * @note  The bzero() function is deprecated (marked as LEGACY in POSIX. 1-2001).
+ */
+void bzero(void* s, size_t n)
+{
+    rt_memset(s, 0, n);
+}
+
+void bcopy(const void* src, void* dest, size_t n)
+{
+    rt_memcpy(dest, src, n);
+}
+
+int bcmp(const void* s1, const void* s2, size_t n)
+{
+    return rt_memcmp(s1, s2, n);
+}
+
+void explicit_bzero(void* s, size_t n)
+{
+    volatile char* vs = (volatile char*)s;
+    while (n)
+    {
+        *vs++ = 0;
+        n--;
+    }
+}
+
+char* index(const char* s, int c)
+{
+    return strchr(s, c);
+}
+
+char* rindex(const char* s, int c)
+{
+    return strrchr(s, c);
+}
+
+int ffs(int i)
+{
+    int bit;
+
+    if (0 == i)
+        return 0;
+
+    for (bit = 1; !(i & 1); ++bit)
+        i >>= 1;
+    return bit;
+}
+
+int ffsl(long i)
+{
+    int bit;
+
+    if (0 == i)
+        return 0;
+
+    for (bit = 1; !(i & 1); ++bit)
+        i >>= 1;
+    return bit;
+}
+
+int ffsll(long long i)
+{
+    int bit;
+
+    if (0 == i)
+        return 0;
+
+    for (bit = 1; !(i & 1); ++bit)
+        i >>= 1;
+    return bit;
+}
+
+/**
+ * @brief The memchr() function scans the initial n bytes of the memory area pointed to
+ *        by s for the first instance of c. Both c and the bytes of the memory area
+ *        pointed to by s are interpreted as unsigned char.
+ *
+ * @note  This function is GNU extension, available since glibc 2.1.91.
+ */
+void* memrchr(const void* ptr, int ch, size_t pos)
+{
+    char* end = (char*)ptr + pos - 1;
+    while (end != ptr)
+    {
+        if (*end == ch)
+            return end;
+        end--;
+    }
+    return (*end == ch) ? (end) : (NULL);
+}
+
+size_t strnlen(const char *s, size_t maxlen)
+{
+    const char *sc;
+    for (sc = s; maxlen != 0 && *sc != '\0'; maxlen--, ++sc);
+    return sc - s;
+}
+
+char* strchrnul(const char* s, int c)
+{
+    while (*s != '\0' && *s != c)
+        s++;
+    return (char*)s;
+}
+
+int strcasecmp(const char* s1, const char* s2)
+{
+    const unsigned char* u1 = (const unsigned char*)s1;
+    const unsigned char* u2 = (const unsigned char*)s2;
+    int result;
+
+    while ((result = tolower(*u1) - tolower(*u2)) == 0 && *u1 != 0)
+    {
+        u1++;
+        u2++;
+    }
+
+    return result;
+}
+
+int strncasecmp(const char* s1, const char* s2, size_t n)
+{
+    const unsigned char* u1 = (const unsigned char*)s1;
+    const unsigned char* u2 = (const unsigned char*)s2;
+    int result;
+
+    for (; n != 0; n--)
+    {
+        result = tolower(*u1) - tolower(*u2);
+        if (result)
+            return result;
+        if (*u1 == 0)
+            return 0;
+        u1++;
+        u2++;
+    }
+    return 0;
+}
+
+char *strdup(const char *s)
+{
+    char *news = (char *)malloc(strlen(s) + 1);
+
+    if (news)
+    {
+        strcpy(news, s);
+    }
+
+    return news;
+}
+
+char *strndup(const char *s, size_t size)
+{
+    size_t nsize = strnlen(s, size);
+    char *news = (char *)malloc(nsize + 1);
+    if (news)
+    {
+        rt_memcpy(news, s, nsize);
+        news[nsize] = '\0';
+    }
+
+    return news;
+}
+
+char *strtok_r(char *str, const char *delim, char **saveptr)
+{
+    char *pbegin;
+    char *pend = NULL;
+
+    if (str)
+    {
+        pbegin = str;
+    }
+    else if (saveptr && *saveptr)
+    {
+        pbegin = *saveptr;
+    }
+    else
+    {
+        return NULL;
+    }
+
+    for (;*pbegin && strchr(delim, *pbegin) != NULL; pbegin++);
+
+    if (!*pbegin)
+    {
+        return NULL;
+    }
+
+    for (pend = pbegin + 1; *pend && strchr(delim, *pend) == NULL; pend++);
+
+    if (*pend)
+    {
+        *pend++ = '\0';
+    }
+
+    if (saveptr)
+    {
+        *saveptr = pend;
+    }
+
+    return pbegin;
+}