[kernel] move std libc related to rtklibc.h

2 files changed, 1193 insertions, 0 deletions

diff --git a/src/klibc/kstdio.c b/src/klibc/kstdio.c
new file mode 100644
index 0000000000..8ed1a9298d
--- /dev/null
+++ b/src/klibc/kstdio.c
@@ -0,0 +1,686 @@
+/*
+ * Copyright (c) 2006-2024, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2024-03-10     Meco Man     the first version
+ */
+
+#include <rtdef.h>
+#include <rtcompiler.h>
+#include <rtklibc.h>
+#include <rtm.h>
+
+#define DBG_TAG           "kernel.stdio"
+#ifdef RT_DEBUG_DEVICE
+#define DBG_LVL           DBG_LOG
+#else
+#define DBG_LVL           DBG_WARNING
+#endif /* defined (RT_DEBUG_DEVICE) */
+#include <rtdbg.h>
+
+/* private function */
+#define _ISDIGIT(c)  ((unsigned)((c) - '0') < 10)
+
+/**
+ * @brief  This function will duplicate a string.
+ *
+ * @param  n is the string to be duplicated.
+ *
+ * @param  base is support divide instructions value.
+ *
+ * @return the duplicated string pointer.
+ */
+#ifdef RT_KPRINTF_USING_LONGLONG
+rt_inline int divide(unsigned long long *n, int base)
+#else
+rt_inline int divide(unsigned long *n, int base)
+#endif /* RT_KPRINTF_USING_LONGLONG */
+{
+    int res;
+
+    /* optimized for processor which does not support divide instructions. */
+#ifdef RT_KPRINTF_USING_LONGLONG
+    res = (int)((*n) % base);
+    *n = (long long)((*n) / base);
+#else
+    res = (int)((*n) % base);
+    *n = (long)((*n) / base);
+#endif
+
+    return res;
+}
+
+rt_inline int skip_atoi(const char **s)
+{
+    int i = 0;
+    while (_ISDIGIT(**s))
+        i = i * 10 + *((*s)++) - '0';
+
+    return i;
+}
+
+#define ZEROPAD     (1 << 0)    /* pad with zero */
+#define SIGN        (1 << 1)    /* unsigned/signed long */
+#define PLUS        (1 << 2)    /* show plus */
+#define SPACE       (1 << 3)    /* space if plus */
+#define LEFT        (1 << 4)    /* left justified */
+#define SPECIAL     (1 << 5)    /* 0x */
+#define LARGE       (1 << 6)    /* use 'ABCDEF' instead of 'abcdef' */
+
+static char *print_number(char *buf,
+                          char *end,
+#ifdef RT_KPRINTF_USING_LONGLONG
+                          unsigned long long  num,
+#else
+                          unsigned long  num,
+#endif /* RT_KPRINTF_USING_LONGLONG */
+                          int   base,
+                          int   qualifier,
+                          int   s,
+                          int   precision,
+                          int   type)
+{
+    char c = 0, sign = 0;
+#ifdef RT_KPRINTF_USING_LONGLONG
+    char tmp[64] = {0};
+#else
+    char tmp[32] = {0};
+#endif /* RT_KPRINTF_USING_LONGLONG */
+    int precision_bak = precision;
+    const char *digits = RT_NULL;
+    static const char small_digits[] = "0123456789abcdef";
+    static const char large_digits[] = "0123456789ABCDEF";
+    int i = 0;
+    int size = 0;
+
+    size = s;
+
+    digits = (type & LARGE) ? large_digits : small_digits;
+    if (type & LEFT)
+    {
+        type &= ~ZEROPAD;
+    }
+
+    c = (type & ZEROPAD) ? '0' : ' ';
+
+    /* get sign */
+    sign = 0;
+    if (type & SIGN)
+    {
+        switch (qualifier)
+        {
+        case 'h':
+            if ((rt_int16_t)num < 0)
+            {
+                sign = '-';
+                num = (rt_uint16_t)-num;
+            }
+            break;
+        case 'L':
+        case 'l':
+            if ((long)num < 0)
+            {
+                sign = '-';
+                num = (unsigned long)-num;
+            }
+            break;
+        case 0:
+        default:
+            if ((rt_int32_t)num < 0)
+            {
+                sign = '-';
+                num = (rt_uint32_t)-num;
+            }
+            break;
+        }
+
+        if (sign != '-')
+        {
+            if (type & PLUS)
+            {
+                sign = '+';
+            }
+            else if (type & SPACE)
+            {
+                sign = ' ';
+            }
+        }
+    }
+
+    if (type & SPECIAL)
+    {
+        if (base == 2 || base == 16)
+        {
+            size -= 2;
+        }
+        else if (base == 8)
+        {
+            size--;
+        }
+    }
+
+    i = 0;
+    if (num == 0)
+    {
+        tmp[i++] = '0';
+    }
+    else
+    {
+        while (num != 0)
+            tmp[i++] = digits[divide(&num, base)];
+    }
+
+    if (i > precision)
+    {
+        precision = i;
+    }
+    size -= precision;
+
+    if (!(type & (ZEROPAD | LEFT)))
+    {
+        if ((sign) && (size > 0))
+        {
+            size--;
+        }
+
+        while (size-- > 0)
+        {
+            if (buf < end)
+            {
+                *buf = ' ';
+            }
+
+            ++ buf;
+        }
+    }
+
+    if (sign)
+    {
+        if (buf < end)
+        {
+            *buf = sign;
+        }
+        -- size;
+        ++ buf;
+    }
+
+    if (type & SPECIAL)
+    {
+        if (base == 2)
+        {
+            if (buf < end)
+                *buf = '0';
+            ++ buf;
+            if (buf < end)
+                *buf = 'b';
+            ++ buf;
+        }
+        else if (base == 8)
+        {
+            if (buf < end)
+                *buf = '0';
+            ++ buf;
+        }
+        else if (base == 16)
+        {
+            if (buf < end)
+            {
+                *buf = '0';
+            }
+
+            ++ buf;
+            if (buf < end)
+            {
+                *buf = type & LARGE ? 'X' : 'x';
+            }
+            ++ buf;
+        }
+    }
+
+    /* no align to the left */
+    if (!(type & LEFT))
+    {
+        while (size-- > 0)
+        {
+            if (buf < end)
+            {
+                *buf = c;
+            }
+
+            ++ buf;
+        }
+    }
+
+    while (i < precision--)
+    {
+        if (buf < end)
+        {
+            *buf = '0';
+        }
+
+        ++ buf;
+    }
+
+    /* put number in the temporary buffer */
+    while (i-- > 0 && (precision_bak != 0))
+    {
+        if (buf < end)
+        {
+            *buf = tmp[i];
+        }
+
+        ++ buf;
+    }
+
+    while (size-- > 0)
+    {
+        if (buf < end)
+        {
+            *buf = ' ';
+        }
+
+        ++ buf;
+    }
+
+    return buf;
+}
+
+#if defined(__GNUC__) && !defined(__ARMCC_VERSION) /* GCC */
+#pragma GCC diagnostic push
+/* ignore warning: this statement may fall through */
+#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+#endif /* defined(__GNUC__) && !defined(__ARMCC_VERSION) */
+/**
+ * @brief  This function will fill a formatted string to buffer.
+ *
+ * @param  buf is the buffer to save formatted string.
+ *
+ * @param  size is the size of buffer.
+ *
+ * @param  fmt is the format parameters.
+ *
+ * @param  args is a list of variable parameters.
+ *
+ * @return The number of characters actually written to buffer.
+ */
+rt_weak int rt_vsnprintf(char *buf, rt_size_t size, const char *fmt, va_list args)
+{
+#ifdef RT_KPRINTF_USING_LONGLONG
+    unsigned long long num = 0;
+#else
+    unsigned long num = 0;
+#endif /* RT_KPRINTF_USING_LONGLONG */
+    int i = 0, len = 0;
+    char *str = RT_NULL, *end = RT_NULL, c = 0;
+    const char *s = RT_NULL;
+
+    rt_uint8_t base = 0;            /* the base of number */
+    rt_uint8_t flags = 0;           /* flags to print number */
+    rt_uint8_t qualifier = 0;       /* 'h', 'l', or 'L' for integer fields */
+    rt_int32_t field_width = 0;     /* width of output field */
+    int precision = 0;      /* min. # of digits for integers and max for a string */
+
+    str = buf;
+    end = buf + size;
+
+    /* Make sure end is always >= buf */
+    if (end < buf)
+    {
+        end  = ((char *) - 1);
+        size = end - buf;
+    }
+
+    for (; *fmt ; ++fmt)
+    {
+        if (*fmt != '%')
+        {
+            if (str < end)
+            {
+                *str = *fmt;
+            }
+
+            ++ str;
+            continue;
+        }
+
+        /* process flags */
+        flags = 0;
+
+        while (1)
+        {
+            /* skips the first '%' also */
+            ++fmt;
+            if (*fmt == '-') flags |= LEFT;
+            else if (*fmt == '+') flags |= PLUS;
+            else if (*fmt == ' ') flags |= SPACE;
+            else if (*fmt == '#') flags |= SPECIAL;
+            else if (*fmt == '0') flags |= ZEROPAD;
+            else break;
+        }
+
+        /* get field width */
+        field_width = -1;
+        if (_ISDIGIT(*fmt))
+        {
+            field_width = skip_atoi(&fmt);
+        }
+        else if (*fmt == '*')
+        {
+            ++fmt;
+            /* it's the next argument */
+            field_width = va_arg(args, int);
+            if (field_width < 0)
+            {
+                field_width = -field_width;
+                flags |= LEFT;
+            }
+        }
+
+        /* get the precision */
+        precision = -1;
+        if (*fmt == '.')
+        {
+            ++fmt;
+            if (_ISDIGIT(*fmt))
+            {
+                precision = skip_atoi(&fmt);
+            }
+            else if (*fmt == '*')
+            {
+                ++fmt;
+                /* it's the next argument */
+                precision = va_arg(args, int);
+            }
+            if (precision < 0)
+            {
+                precision = 0;
+            }
+        }
+
+        qualifier = 0; /* get the conversion qualifier */
+
+        if (*fmt == 'h' || *fmt == 'l' ||
+#ifdef RT_KPRINTF_USING_LONGLONG
+            *fmt == 'L' ||
+#endif /* RT_KPRINTF_USING_LONGLONG */
+            *fmt == 'z')
+        {
+            qualifier = *fmt;
+            ++fmt;
+#ifdef RT_KPRINTF_USING_LONGLONG
+            if (qualifier == 'l' && *fmt == 'l')
+            {
+                qualifier = 'L';
+                ++fmt;
+            }
+#endif /* RT_KPRINTF_USING_LONGLONG */
+            if (qualifier == 'h' && *fmt == 'h')
+            {
+                qualifier = 'H';
+                ++fmt;
+            }
+        }
+
+        /* the default base */
+        base = 10;
+
+        switch (*fmt)
+        {
+        case 'c':
+            if (!(flags & LEFT))
+            {
+                while (--field_width > 0)
+                {
+                    if (str < end) *str = ' ';
+                    ++ str;
+                }
+            }
+
+            /* get character */
+            c = (rt_uint8_t)va_arg(args, int);
+            if (str < end)
+            {
+                *str = c;
+            }
+            ++ str;
+
+            /* put width */
+            while (--field_width > 0)
+            {
+                if (str < end) *str = ' ';
+                ++ str;
+            }
+            continue;
+
+        case 's':
+            s = va_arg(args, char *);
+            if (!s)
+            {
+                s = "(NULL)";
+            }
+
+            for (len = 0; (len != field_width) && (s[len] != '\0'); len++);
+
+            if (precision > 0 && len > precision)
+            {
+                len = precision;
+            }
+
+            if (!(flags & LEFT))
+            {
+                while (len < field_width--)
+                {
+                    if (str < end) *str = ' ';
+                    ++ str;
+                }
+            }
+
+            for (i = 0; i < len; ++i)
+            {
+                if (str < end) *str = *s;
+                ++ str;
+                ++ s;
+            }
+
+            while (len < field_width--)
+            {
+                if (str < end) *str = ' ';
+                ++ str;
+            }
+            continue;
+
+        case 'p':
+            if (field_width == -1)
+            {
+                field_width = sizeof(void *) << 1;
+                field_width += 2; /* `0x` prefix */
+                flags |= SPECIAL;
+                flags |= ZEROPAD;
+            }
+            str = print_number(str, end, (unsigned long)va_arg(args, void *),
+                               16, qualifier, field_width, precision, flags);
+            continue;
+
+        case '%':
+            if (str < end)
+            {
+                *str = '%';
+            }
+            ++ str;
+            continue;
+
+        /* integer number formats - set up the flags and "break" */
+        case 'b':
+            base = 2;
+            break;
+        case 'o':
+            base = 8;
+            break;
+
+        case 'X':
+            flags |= LARGE;
+        case 'x':
+            base = 16;
+            break;
+
+        case 'd':
+        case 'i':
+            flags |= SIGN;
+        case 'u':
+            break;
+
+        case 'e':
+        case 'E':
+        case 'G':
+        case 'g':
+        case 'f':
+        case 'F':
+            va_arg(args, double);
+        default:
+            if (str < end)
+            {
+                *str = '%';
+            }
+            ++ str;
+
+            if (*fmt)
+            {
+                if (str < end)
+                {
+                    *str = *fmt;
+                }
+                ++ str;
+            }
+            else
+            {
+                -- fmt;
+            }
+            continue;
+        }
+
+        if (qualifier == 'L')
+        {
+            num = va_arg(args, unsigned long long);
+        }
+        else if (qualifier == 'l')
+        {
+            num = va_arg(args, unsigned long);
+        }
+        else if (qualifier == 'H')
+        {
+            num = (rt_int8_t)va_arg(args, rt_int32_t);
+            if (flags & SIGN)
+            {
+                num = (rt_int8_t)num;
+            }
+        }
+        else if (qualifier == 'h')
+        {
+            num = (rt_uint16_t)va_arg(args, rt_int32_t);
+            if (flags & SIGN)
+            {
+                num = (rt_int16_t)num;
+            }
+        }
+        else if (qualifier == 'z')
+        {
+            num = va_arg(args, rt_size_t);
+            if (flags & SIGN)
+            {
+                num = (rt_ssize_t)num;
+            }
+        }
+        else
+        {
+            num = (rt_uint32_t)va_arg(args, unsigned long);
+        }
+        str = print_number(str, end, num, base, qualifier, field_width, precision, flags);
+    }
+
+    if (size > 0)
+    {
+        if (str < end)
+        {
+            *str = '\0';
+        }
+        else
+        {
+            end[-1] = '\0';
+        }
+    }
+
+    /* the trailing null byte doesn't count towards the total
+    * ++str;
+    */
+    return str - buf;
+}
+RTM_EXPORT(rt_vsnprintf);
+#if defined(__GNUC__) && !defined(__ARMCC_VERSION) /* GCC */
+#pragma GCC diagnostic pop /* ignored "-Wimplicit-fallthrough" */
+#endif /* defined(__GNUC__) && !defined(__ARMCC_VERSION) */
+
+/**
+ * @brief  This function will fill a formatted string to buffer.
+ *
+ * @param  buf is the buffer to save formatted string.
+ *
+ * @param  size is the size of buffer.
+ *
+ * @param  fmt is the format parameters.
+ *
+ * @return The number of characters actually written to buffer.
+ */
+int rt_snprintf(char *buf, rt_size_t size, const char *fmt, ...)
+{
+    rt_int32_t n = 0;
+    va_list args;
+
+    va_start(args, fmt);
+    n = rt_vsnprintf(buf, size, fmt, args);
+    va_end(args);
+
+    return n;
+}
+RTM_EXPORT(rt_snprintf);
+
+/**
+ * @brief  This function will fill a formatted string to buffer.
+ *
+ * @param  buf is the buffer to save formatted string.
+ *
+ * @param  format is the format parameters.
+ *
+ * @param  arg_ptr is a list of variable parameters.
+ *
+ * @return The number of characters actually written to buffer.
+ */
+int rt_vsprintf(char *buf, const char *format, va_list arg_ptr)
+{
+    return rt_vsnprintf(buf, (rt_size_t) - 1, format, arg_ptr);
+}
+RTM_EXPORT(rt_vsprintf);
+
+/**
+ * @brief  This function will fill a formatted string to buffer
+ *
+ * @param  buf the buffer to save formatted string.
+ *
+ * @param  format is the format parameters.
+ *
+ * @return The number of characters actually written to buffer.
+ */
+int rt_sprintf(char *buf, const char *format, ...)
+{
+    rt_int32_t n = 0;
+    va_list arg_ptr;
+
+    va_start(arg_ptr, format);
+    n = rt_vsprintf(buf, format, arg_ptr);
+    va_end(arg_ptr);
+
+    return n;
+}
+RTM_EXPORT(rt_sprintf);
diff --git a/src/klibc/kstring.c b/src/klibc/kstring.c
new file mode 100644
index 0000000000..016412071b
--- /dev/null
+++ b/src/klibc/kstring.c
@@ -0,0 +1,507 @@
+/*
+ * Copyright (c) 2006-2024, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2024-03-10     Meco Man     the first version
+ */
+
+#include <rtdef.h>
+#include <rtcompiler.h>
+#include <rtklibc.h>
+#include <rtm.h>
+
+#define DBG_TAG           "kernel.string"
+#ifdef RT_DEBUG_DEVICE
+#define DBG_LVL           DBG_LOG
+#else
+#define DBG_LVL           DBG_WARNING
+#endif /* defined (RT_DEBUG_DEVICE) */
+#include <rtdbg.h>
+
+#ifndef RT_KSERVICE_USING_STDLIB_MEMORY
+/**
+ * @brief  This function will set the content of memory to specified value.
+ *
+ * @param  s is the address of source memory, point to the memory block to be filled.
+ *
+ * @param  c is the value to be set. The value is passed in int form, but the function
+ *         uses the unsigned character form of the value when filling the memory block.
+ *
+ * @param  count number of bytes to be set.
+ *
+ * @return The address of source memory.
+ */
+rt_weak void *rt_memset(void *s, int c, rt_ubase_t count)
+{
+#ifdef RT_KSERVICE_USING_TINY_SIZE
+    char *xs = (char *)s;
+
+    while (count--)
+        *xs++ = c;
+
+    return s;
+#else
+#define LBLOCKSIZE      (sizeof(rt_ubase_t))
+#define UNALIGNED(X)    ((long)X & (LBLOCKSIZE - 1))
+#define TOO_SMALL(LEN)  ((LEN) < LBLOCKSIZE)
+
+    unsigned int i = 0;
+    char *m = (char *)s;
+    unsigned long buffer = 0;
+    unsigned long *aligned_addr = RT_NULL;
+    unsigned char d = (unsigned int)c & (unsigned char)(-1);  /* To avoid sign extension, copy C to an
+                                unsigned variable. (unsigned)((char)(-1))=0xFF for 8bit and =0xFFFF for 16bit: word independent */
+
+    RT_ASSERT(LBLOCKSIZE == 2 || LBLOCKSIZE == 4 || LBLOCKSIZE == 8);
+
+    if (!TOO_SMALL(count) && !UNALIGNED(s))
+    {
+        /* If we get this far, we know that count is large and s is word-aligned. */
+        aligned_addr = (unsigned long *)s;
+
+        /* Store d into each char sized location in buffer so that
+         * we can set large blocks quickly.
+         */
+        for (i = 0; i < LBLOCKSIZE; i++)
+        {
+            *(((unsigned char *)&buffer)+i) = d;
+        }
+
+        while (count >= LBLOCKSIZE * 4)
+        {
+            *aligned_addr++ = buffer;
+            *aligned_addr++ = buffer;
+            *aligned_addr++ = buffer;
+            *aligned_addr++ = buffer;
+            count -= 4 * LBLOCKSIZE;
+        }
+
+        while (count >= LBLOCKSIZE)
+        {
+            *aligned_addr++ = buffer;
+            count -= LBLOCKSIZE;
+        }
+
+        /* Pick up the remainder with a bytewise loop. */
+        m = (char *)aligned_addr;
+    }
+
+    while (count--)
+    {
+        *m++ = (char)d;
+    }
+
+    return s;
+
+#undef LBLOCKSIZE
+#undef UNALIGNED
+#undef TOO_SMALL
+#endif /* RT_KSERVICE_USING_TINY_SIZE */
+}
+RTM_EXPORT(rt_memset);
+
+/**
+ * @brief  This function will copy memory content from source address to destination address.
+ *
+ * @param  dst is the address of destination memory, points to the copied content.
+ *
+ * @param  src  is the address of source memory, pointing to the data source to be copied.
+ *
+ * @param  count is the copied length.
+ *
+ * @return The address of destination memory
+ */
+rt_weak void *rt_memcpy(void *dst, const void *src, rt_ubase_t count)
+{
+#ifdef RT_KSERVICE_USING_TINY_SIZE
+    char *tmp = (char *)dst, *s = (char *)src;
+    rt_ubase_t len = 0;
+
+    if (tmp <= s || tmp > (s + count))
+    {
+        while (count--)
+            *tmp ++ = *s ++;
+    }
+    else
+    {
+        for (len = count; len > 0; len --)
+            tmp[len - 1] = s[len - 1];
+    }
+
+    return dst;
+#else
+
+#define UNALIGNED(X, Y) \
+    (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+#define BIGBLOCKSIZE    (sizeof (long) << 2)
+#define LITTLEBLOCKSIZE (sizeof (long))
+#define TOO_SMALL(LEN)  ((LEN) < BIGBLOCKSIZE)
+
+    char *dst_ptr = (char *)dst;
+    char *src_ptr = (char *)src;
+    long *aligned_dst = RT_NULL;
+    long *aligned_src = RT_NULL;
+    rt_ubase_t len = count;
+
+    /* If the size is small, or either SRC or DST is unaligned,
+    then punt into the byte copy loop.  This should be rare. */
+    if (!TOO_SMALL(len) && !UNALIGNED(src_ptr, dst_ptr))
+    {
+        aligned_dst = (long *)dst_ptr;
+        aligned_src = (long *)src_ptr;
+
+        /* Copy 4X long words at a time if possible. */
+        while (len >= BIGBLOCKSIZE)
+        {
+            *aligned_dst++ = *aligned_src++;
+            *aligned_dst++ = *aligned_src++;
+            *aligned_dst++ = *aligned_src++;
+            *aligned_dst++ = *aligned_src++;
+            len -= BIGBLOCKSIZE;
+        }
+
+        /* Copy one long word at a time if possible. */
+        while (len >= LITTLEBLOCKSIZE)
+        {
+            *aligned_dst++ = *aligned_src++;
+            len -= LITTLEBLOCKSIZE;
+        }
+
+        /* Pick up any residual with a byte copier. */
+        dst_ptr = (char *)aligned_dst;
+        src_ptr = (char *)aligned_src;
+    }
+
+    while (len--)
+        *dst_ptr++ = *src_ptr++;
+
+    return dst;
+#undef UNALIGNED
+#undef BIGBLOCKSIZE
+#undef LITTLEBLOCKSIZE
+#undef TOO_SMALL
+#endif /* RT_KSERVICE_USING_TINY_SIZE */
+}
+RTM_EXPORT(rt_memcpy);
+
+/**
+ * @brief  This function will move memory content from source address to destination
+ * address. If the destination memory does not overlap with the source memory,
+ * the function is the same as memcpy().
+ *
+ * @param  dest is the address of destination memory, points to the copied content.
+ *
+ * @param  src is the address of source memory, point to the data source to be copied.
+ *
+ * @param  n is the copied length.
+ *
+ * @return The address of destination memory.
+ */
+void *rt_memmove(void *dest, const void *src, rt_size_t n)
+{
+    char *tmp = (char *)dest, *s = (char *)src;
+
+    if (s < tmp && tmp < s + n)
+    {
+        tmp += n;
+        s += n;
+
+        while (n--)
+            *(--tmp) = *(--s);
+    }
+    else
+    {
+        while (n--)
+            *tmp++ = *s++;
+    }
+
+    return dest;
+}
+RTM_EXPORT(rt_memmove);
+
+/**
+ * @brief  This function will compare two areas of memory.
+ *
+ * @param  cs is a block of memory.
+ *
+ * @param  ct is another block of memory.
+ *
+ * @param  count is the size of the area.
+ *
+ * @return Compare the results:
+ *         If the result < 0, cs is smaller than ct.
+ *         If the result > 0, cs is greater than ct.
+ *         If the result = 0, cs is equal to ct.
+ */
+rt_int32_t rt_memcmp(const void *cs, const void *ct, rt_size_t count)
+{
+    const unsigned char *su1 = RT_NULL, *su2 = RT_NULL;
+    int res = 0;
+
+    for (su1 = (const unsigned char *)cs, su2 = (const unsigned char *)ct; 0 < count; ++su1, ++su2, count--)
+        if ((res = *su1 - *su2) != 0)
+            break;
+
+    return res;
+}
+RTM_EXPORT(rt_memcmp);
+#endif /* RT_KSERVICE_USING_STDLIB_MEMORY*/
+
+#ifndef RT_KSERVICE_USING_STDLIB
+/**
+ * @brief  This function will return the first occurrence of a string, without the
+ * terminator '\0'.
+ *
+ * @param  s1 is the source string.
+ *
+ * @param  s2 is the find string.
+ *
+ * @return The first occurrence of a s2 in s1, or RT_NULL if no found.
+ */
+char *rt_strstr(const char *s1, const char *s2)
+{
+    int l1 = 0, l2 = 0;
+
+    l2 = rt_strlen(s2);
+    if (!l2)
+    {
+        return (char *)s1;
+    }
+
+    l1 = rt_strlen(s1);
+    while (l1 >= l2)
+    {
+        l1 --;
+        if (!rt_memcmp(s1, s2, l2))
+        {
+            return (char *)s1;
+        }
+
+        s1 ++;
+    }
+
+    return RT_NULL;
+}
+RTM_EXPORT(rt_strstr);
+
+/**
+ * @brief  This function will compare two strings while ignoring differences in case
+ *
+ * @param  a is the string to be compared.
+ *
+ * @param  b is the string to be compared.
+ *
+ * @return Compare the results:
+ *         If the result < 0, a is smaller than a.
+ *         If the result > 0, a is greater than a.
+ *         If the result = 0, a is equal to a.
+ */
+rt_int32_t rt_strcasecmp(const char *a, const char *b)
+{
+    int ca = 0, cb = 0;
+
+    do
+    {
+        ca = *a++ & 0xff;
+        cb = *b++ & 0xff;
+        if (ca >= 'A' && ca <= 'Z')
+            ca += 'a' - 'A';
+        if (cb >= 'A' && cb <= 'Z')
+            cb += 'a' - 'A';
+    }
+    while (ca == cb && ca != '\0');
+
+    return ca - cb;
+}
+RTM_EXPORT(rt_strcasecmp);
+
+/**
+ * @brief  This function will copy string no more than n bytes.
+ *
+ * @param  dst points to the address used to store the copied content.
+ *
+ * @param  src is the string to be copied.
+ *
+ * @param  n is the maximum copied length.
+ *
+ * @return The address where the copied content is stored.
+ */
+char *rt_strncpy(char *dst, const char *src, rt_size_t n)
+{
+    if (n != 0)
+    {
+        char *d = dst;
+        const char *s = src;
+
+        do
+        {
+            if ((*d++ = *s++) == 0)
+            {
+                /* NUL pad the remaining n-1 bytes */
+                while (--n != 0)
+                {
+                    *d++ = 0;
+                }
+
+                break;
+            }
+        } while (--n != 0);
+    }
+
+    return (dst);
+}
+RTM_EXPORT(rt_strncpy);
+
+/**
+ * @brief  This function will copy string.
+ *
+ * @param  dst points to the address used to store the copied content.
+ *
+ * @param  src is the string to be copied.
+ *
+ * @return The address where the copied content is stored.
+ */
+char *rt_strcpy(char *dst, const char *src)
+{
+    char *dest = dst;
+
+    while (*src != '\0')
+    {
+        *dst = *src;
+        dst++;
+        src++;
+    }
+
+    *dst = '\0';
+    return dest;
+}
+RTM_EXPORT(rt_strcpy);
+
+/**
+ * @brief  This function will compare two strings with specified maximum length.
+ *
+ * @param  cs is the string to be compared.
+ *
+ * @param  ct is the string to be compared.
+ *
+ * @param  count is the maximum compare length.
+ *
+ * @return Compare the results:
+ *         If the result < 0, cs is smaller than ct.
+ *         If the result > 0, cs is greater than ct.
+ *         If the result = 0, cs is equal to ct.
+ */
+rt_int32_t rt_strncmp(const char *cs, const char *ct, rt_size_t count)
+{
+    signed char __res = 0;
+
+    while (count)
+    {
+        if ((__res = *cs - *ct++) != 0 || !*cs++)
+        {
+            break;
+        }
+
+        count --;
+    }
+
+    return __res;
+}
+RTM_EXPORT(rt_strncmp);
+
+/**
+ * @brief  This function will compare two strings without specified length.
+ *
+ * @param  cs is the string to be compared.
+ *
+ * @param  ct is the string to be compared.
+ *
+ * @return Compare the results:
+ *         If the result < 0, cs is smaller than ct.
+ *         If the result > 0, cs is greater than ct.
+ *         If the result = 0, cs is equal to ct.
+ */
+rt_int32_t rt_strcmp(const char *cs, const char *ct)
+{
+    while (*cs && *cs == *ct)
+    {
+        cs++;
+        ct++;
+    }
+
+    return (*cs - *ct);
+}
+RTM_EXPORT(rt_strcmp);
+
+/**
+ * @brief  This function will return the length of a string, which terminate will
+ * null character.
+ *
+ * @param  s is the string
+ *
+ * @return The length of string.
+ */
+rt_size_t rt_strlen(const char *s)
+{
+    const char *sc = RT_NULL;
+
+    for (sc = s; *sc != '\0'; ++sc) /* nothing */
+        ;
+
+    return sc - s;
+}
+RTM_EXPORT(rt_strlen);
+
+#endif /* RT_KSERVICE_USING_STDLIB */
+
+/**
+ * @brief  The  strnlen()  function  returns the number of characters in the
+ * string pointed to by s, excluding the terminating null byte ('\0'),
+ * but at most maxlen.  In doing this, strnlen() looks only at the
+ * first maxlen characters in the string pointed to by s and never
+ * beyond s+maxlen.
+ *
+ * @param  s is the string.
+ *
+ * @param  maxlen is the max size.
+ *
+ * @return The length of string.
+ */
+rt_size_t rt_strnlen(const char *s, rt_ubase_t maxlen)
+{
+    const char *sc;
+
+    for (sc = s; *sc != '\0' && (rt_ubase_t)(sc - s) < maxlen; ++sc) /* nothing */
+        ;
+
+    return sc - s;
+}
+RTM_EXPORT(rt_strnlen);
+
+#ifdef RT_USING_HEAP
+/**
+ * @brief  This function will duplicate a string.
+ *
+ * @param  s is the string to be duplicated.
+ *
+ * @return The string address of the copy.
+ */
+char *rt_strdup(const char *s)
+{
+    rt_size_t len = rt_strlen(s) + 1;
+    char *tmp = (char *)rt_malloc(len);
+
+    if (!tmp)
+    {
+        return RT_NULL;
+    }
+
+    rt_memcpy(tmp, s, len);
+
+    return tmp;
+}
+RTM_EXPORT(rt_strdup);
+#endif /* RT_USING_HEAP */