WebSVN – HelenOS – Diff – /trunk/kernel/generic/src/lib/string.c

 /*
  * Copyright (c) 2001-2004 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup generic
  * @{
  */
 /**
  * @file
  * @brief Miscellaneous functions.
  */
 #include <string.h>
 #include <print.h>
 #include <cpu.h>
 #include <arch/asm.h>
 #include <arch.h>
 #include <console/kconsole.h>
+/** Decode a single UTF-8 character from a NULL-terminated string.
+ *
+ * Decode a single UTF-8 character from a plain char NULL-terminated
+ * string. Decoding starts at @index and this index is incremented
+ * if the current UTF-8 string is encoded in more than a single byte.
+ *
+ * @param str   Plain character NULL-terminated string.
+ * @param index Index (counted in plain characters) where to start
+ *              the decoding.
+ *
+ * @return Decoded character in UTF-32 or '?' if the encoding is wrong.
+ *
+ */
+wchar_t utf8_decode(const char *str, index_t *index)
+{
+    uint8_t c1;           /* First plain character from str */
+    uint8_t c2;           /* Second plain character from str */
+    uint8_t c3;           /* Third plain character from str */
+    uint8_t c4;           /* Fourth plain character from str */
+    c1 = (uint8_t) str[*index];
+    if ((c1 & 0x80) == 0) {
+        /* Plain ASCII (code points 0 .. 127) */
+        return (wchar_t) c1;
+    } else if ((c1 & 0xe0) == 0xc0) {
+        /* Code points 128 .. 2047 */
+        c2 = (uint8_t) str[*index + 1];
+        if ((c2 & 0xc0) == 0x80) {
+            (*index)++;
+            return ((wchar_t) ((c1 & 0x1f) << 6) | (c2 & 0x3f));
+        } else
+            return ((wchar_t) '?');
+    } else if ((c1 & 0xf0) == 0xe0) {
+        /* Code points 2048 .. 65535 */
+        c2 = (uint8_t) str[*index + 1];
+        if ((c2 & 0xc0) == 0x80) {
+            (*index)++;
+            c3 = (uint8_t) str[*index + 1];
+            if ((c3 & 0xc0) == 0x80) {
+                (*index)++;
+                return ((wchar_t) ((c1 & 0x0f) << 12) | ((c2 & 0x3f) << 6) | (c3 & 0x3f));
+            } else
+                return ((wchar_t) '?');
+        } else
+            return ((wchar_t) '?');
+    } else if ((c1 & 0xf8) == 0xf0) {
+        /* Code points 65536 .. 1114111 */
+        c2 = (uint8_t) str[*index + 1];
+        if ((c2 & 0xc0) == 0x80) {
+            (*index)++;
+            c3 = (uint8_t) str[*index + 1];
+            if ((c3 & 0xc0) == 0x80) {
+                (*index)++;
+                c4 = (uint8_t) str[*index + 1];
+                if ((c4 & 0xc0) == 0x80) {
+                    (*index)++;
+                    return ((wchar_t) ((c1 & 0x07) << 18) | ((c2 & 0x3f) << 12) | ((c3 & 0x3f) << 6) | (c4 & 0x3f));
+                } else
+                    return ((wchar_t) '?');
+            } else
+                return ((wchar_t) '?');
+        } else
+            return ((wchar_t) '?');
+    }
+    return ((wchar_t) '?');
+}
 /** Return number of characters in a string.
+ *
  * @param str NULL terminated string.
+ *
  * @return Number of characters in str.
+ *
  */
 size_t strlen(const char *str)
+{
     int i;
     for (i = 0; str[i]; i++);
     return i;
+}
 /** Compare two NULL terminated strings
+ *
  * Do a char-by-char comparison of two NULL terminated strings.
  * The strings are considered equal iff they consist of the same
  * characters on the minimum of their lengths.
+ *
  * @param src First string to compare.
  * @param dst Second string to compare.
+ *
  * @return 0 if the strings are equal, -1 if first is smaller, 1 if second smaller.
+ *
  */
 int strcmp(const char *src, const char *dst)
+{
     for (; *src && *dst; src++, dst++) {
         if (*src < *dst)
             return -1;
         if (*src > *dst)
             return 1;
+    }
     if (*src == *dst)
         return 0;
     if (!*src)
         return -1;
     return 1;
+}
 /** Compare two NULL terminated strings
+ *
  * Do a char-by-char comparison of two NULL terminated strings.
  * The strings are considered equal iff they consist of the same
  * characters on the minimum of their lengths and specified maximal
  * length.
+ *
  * @param src First string to compare.
  * @param dst Second string to compare.
  * @param len Maximal length for comparison.
+ *
  * @return 0 if the strings are equal, -1 if first is smaller, 1 if second smaller.
+ *
  */
 int strncmp(const char *src, const char *dst, size_t len)
+{
     unsigned int i;
     for (i = 0; (*src) && (*dst) && (i < len); src++, dst++, i++) {
         if (*src < *dst)
             return -1;
         if (*src > *dst)
             return 1;
+    }
     if (i == len || *src == *dst)
         return 0;
     if (!*src)
         return -1;
     return 1;
+}
 /** Copy NULL terminated string.
+ *
  * Copy at most 'len' characters from string 'src' to 'dest'.
  * If 'src' is shorter than 'len', '\0' is inserted behind the
  * last copied character.
+ *
  * @param src  Source string.
  * @param dest Destination buffer.
  * @param len  Size of destination buffer.
+ *
  */
 void strncpy(char *dest, const char *src, size_t len)
+{
     unsigned int i;
     for (i = 0; i < len; i++) {
         if (!(dest[i] = src[i]))
             return;
+    }
     dest[i - 1] = '\0';
+}
 /** Find first occurence of character in string.
+ *
  * @param s String to search.
  * @param i Character to look for.
+ *
  * @return Pointer to character in @a s or NULL if not found.
  */
 extern char *strchr(const char *s, int i)
+{
     while (*s != '\0') {
         if (*s == i)
             return (char *) s;
         ++s;
+    }
     return NULL;
+}
 /** @}
  */

Subversion Repositories HelenOS

(root)/trunk/kernel/generic/src/lib/string.c – Rev 4014 → 4175