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

 #include <cpu.h>
 #include <arch/asm.h>
 #include <arch.h>
 #include <console/kconsole.h>
+char invalch = '?';
+/** 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.
+ *
-/** Return number of characters in a string.
+ * @param str   Plain character NULL-terminated string.
+ * @param index Index (counted in plain characters) where to start
+ *              the decoding.
+ * @param limit Maximal allowed value of index.
+ *
+ * @return Decoded character in UTF-32 or '?' if the encoding is wrong.
+ *
+ */
+wchar_t utf8_decode(const char *str, index_t *index, index_t limit)
+{
+    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 */
+    if (*index > limit)
+        return invalch;
+    c1 = (uint8_t) str[*index];
+    if ((c1 & 0x80) == 0) {
+        /* Plain ASCII (code points 0 .. 127) */
+        return (wchar_t) c1;
+    }
+    if ((c1 & 0xe0) == 0xc0) {
+        /* Code points 128 .. 2047 */
+        if (*index + 1 > limit)
+            return invalch;
+        c2 = (uint8_t) str[*index + 1];
+        if ((c2 & 0xc0) == 0x80) {
+            (*index)++;
+            return ((wchar_t) ((c1 & 0x1f) << 6) | (c2 & 0x3f));
+        } else
+            return invalch;
+    }
+    if ((c1 & 0xf0) == 0xe0) {
+        /* Code points 2048 .. 65535 */
+        if (*index + 2 > limit)
+            return invalch;
+        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 invalch;
+        } else
+            return invalch;
+    }
+    if ((c1 & 0xf8) == 0xf0) {
+        /* Code points 65536 .. 1114111 */
+        if (*index + 3 > limit)
+            return invalch;
+        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 invalch;
+            } else
+                return invalch;
+        } else
+            return invalch;
+    }
+    return invalch;
+}
+/** Encode a single UTF-32 character as UTF-8
+ *
+ * Encode a single UTF-32 character as UTF-8 and store it into
+ * the given buffer at @index. Encoding starts at @index and
+ * this index is incremented if the UTF-8 character takes
+ * more than a single byte.
+ *
+ * @param ch    Input UTF-32 character.
+ * @param str   Output buffer.
+ * @param index Index (counted in plain characters) where to start
+ *              the encoding
+ * @param limit Maximal allowed value of index.
+ *
+ * @return True if the character was encoded or false if there is not
+ *         enought space in the output buffer or the character is invalid
+ *         Unicode code point.
+ *
+ */
+bool utf8_encode(const wchar_t ch, char *str, index_t *index, index_t limit)
+{
+    if (*index > limit)
+        return false;
+    if ((ch >= 0) && (ch <= 127)) {
+        /* Plain ASCII (code points 0 .. 127) */
+        str[*index] = ch & 0x7f;
+        return true;
+    }
+    if ((ch >= 128) && (ch <= 2047)) {
+        /* Code points 128 .. 2047 */
+        if (*index + 1 > limit)
+            return false;
+        str[*index] = 0xc0 | ((ch >> 6) & 0x1f);
+        (*index)++;
+        str[*index] = 0x80 | (ch & 0x3f);
+        return true;
+    }
+    if ((ch >= 2048) && (ch <= 65535)) {
+        /* Code points 2048 .. 65535 */
+        if (*index + 2 > limit)
+            return false;
+        str[*index] = 0xe0 | ((ch >> 12) & 0x0f);
+        (*index)++;
+        str[*index] = 0x80 | ((ch >> 6) & 0x3f);
+        (*index)++;
+        str[*index] = 0x80 | (ch & 0x3f);
+        return true;
+    }
+    if ((ch >= 65536) && (ch <= 1114111)) {
+        /* Code points 65536 .. 1114111 */
+        if (*index + 3 > limit)
+            return false;
+        str[*index] = 0xf0 | ((ch >> 18) & 0x07);
+        (*index)++;
+        str[*index] = 0x80 | ((ch >> 12) & 0x3f);
+        (*index)++;
+        str[*index] = 0x80 | ((ch >> 6) & 0x3f);
+        (*index)++;
+        str[*index] = 0x80 | (ch & 0x3f);
+        return true;
+    }
+    return false;
+}
+/** Get bytes used by UTF-8 characters.
+ *
+ * Get the number of bytes (count of plain characters) which
+ * are used by a given count of UTF-8 characters in a string.
+ * As UTF-8 encoding is multibyte, there is no constant
+ * correspondence between number of characters and used bytes.
+ *
+ * @param str   UTF-8 string to consider.
+ * @param count Number of UTF-8 characters to count.
+ *
+ * @return Number of bytes used by the characters.
+ *
+ */
+size_t utf8_count_bytes(const char *str, count_t count)
+{
+    size_t size = 0;
+    index_t index = 0;
+    while ((utf8_decode(str, &index, UTF8_NO_LIMIT) != 0) && (size < count)) {
+        size++;
+        index++;
+    }
+    return index;
+}
+/** Check whether character is plain ASCII.
+ *
+ * @return True if character is plain ASCII.
+ *
+ */
+bool ascii_check(const wchar_t ch)
+{
+    if ((ch >= 0) && (ch <= 127))
+        return true;
+    return false;
+}
+/** Check whether character is Unicode.
+ *
+ * @return True if character is valid Unicode code point.
+ *
+ */
+bool unicode_check(const wchar_t ch)
+{
+    if ((ch >= 0) && (ch <= 1114111))
+        return true;
+    return false;
+}
+/** Return number of plain characters in a string.
+ *
- * @param str NULL terminated string.
+ * @param str NULL-terminated string.
+ *
  * @return Number of characters in str.
+ *
  */
 size_t strlen(const char *str)
+{
-    int i;
+    size_t size;
+    for (size = 0; str[size]; size++);
+    return size;
+}
+/** Return number of UTF-8 characters in a string.
+ *
+ * @param str NULL-terminated UTF-8 string.
+ *
+ * @return Number of UTF-8 characters in str.
+ *
+ */
+size_t strlen_utf8(const char *str)
+{
+    size_t size = 0;
+    index_t index = 0;
+    while (utf8_decode(str, &index, UTF8_NO_LIMIT) != 0) {
+        size++;
+        index++;
+    }
+    return size;
+}
+/** Return number of UTF-32 characters in a string.
+ *
+ * @param str NULL-terminated UTF-32 string.
+ *
+ * @return Number of UTF-32 characters in str.
+ *
+ */
+size_t strlen_utf32(const wchar_t *str)
+{
+    size_t size;
-    for (i = 0; str[i]; i++);
+    for (size = 0; str[size]; size++);
-    return i;
+    return size;
+}
 /** Compare two NULL terminated strings
+ *
  * Do a char-by-char comparison of two NULL terminated strings.

Subversion Repositories HelenOS

(root)/branches/dynload/kernel/generic/src/lib/string.c – Rev 4345 → 4347