WebSVN – HelenOS – Diff – /branches/dd/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>
+char invalch = '?';
+/** Byte mask consisting of lowest @n bits (out of eight). */
+#define LO_MASK_8(n) ((uint8_t)((1 << (n)) - 1))
+/** Byte mask consisting of lowest @n bits (out of 32). */
+#define LO_MASK_32(n) ((uint32_t)((1 << (n)) - 1))
+/** Byte mask consisting of highest @n bits (out of eight). */
+#define HI_MASK_8(n) (~LO_MASK_8(8 - (n)))
+/** Number of data bits in a UTF-8 continuation byte. */
+#define CONT_BITS 6
-/** Return number of characters in a string.
+/** Decode a single character from a substring.
+ *
+ * Decode a single character from a substring of size @a sz. Decoding starts
+ * at @a offset and this offset is moved to the beginning of the next
+ * character. In case of decoding error, offset generally advances at least
+ * by one. However, offset is never moved beyond (str + sz).
+ *
+ * @param str   String (not necessarily NULL-terminated).
+ * @param index Index (counted in plain characters) where to start
+ *              the decoding.
+ * @param limit Size of the substring.
+ *
+ * @return  Value of decoded character or '?' on decoding error.
+ *
+ */
+wchar_t chr_decode(const char *str, size_t *offset, size_t sz)
+{
+    uint8_t b0, b;          /* Bytes read from str. */
+    wchar_t ch;
+    int b0_bits;        /* Data bits in first byte. */
+    int cbytes;     /* Number of continuation bytes. */
+    if (*offset + 1 > sz)
+        return invalch;
+    b0 = (uint8_t) str[(*offset)++];
+    /* Determine code length. */
+    if ((b0 & 0x80) == 0) {
+        /* 0xxxxxxx (Plain ASCII) */
+        b0_bits = 7;
+        cbytes = 0;
+    } else if ((b0 & 0xe0) == 0xc0) {
+        /* 110xxxxx 10xxxxxx */
+        b0_bits = 5;
+        cbytes = 1;
+    } else if ((b0 & 0xf0) == 0xe0) {
+        /* 1110xxxx 10xxxxxx 10xxxxxx */
+        b0_bits = 4;
+        cbytes = 2;
+    } else if ((b0 & 0xf8) == 0xf0) {
+        /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
+        b0_bits = 3;
+        cbytes = 3;
+    } else {
+        /* 10xxxxxx -- unexpected continuation byte. */
+        return invalch;
+    }
+    if (*offset + cbytes > sz) {
+        return invalch;
+    }
+    ch = b0 & LO_MASK_8(b0_bits);
+    /* Decode continuation bytes. */
+    while (cbytes > 0) {
+        b = (uint8_t) str[(*offset)++];
+        /* Must be 10xxxxxx. */
+        if ((b & 0xc0) != 0x80) {
+            return invalch;
+        }
+        /* Shift data bits to ch. */
+        ch = (ch << CONT_BITS) | (wchar_t) (b & LO_MASK_8(CONT_BITS));
+        --cbytes;
+    }
+    return ch;
+}
+/** Encode a single character to string representation.
+ *
+ * Encode a single character to string representation (i.e. UTF-8) and store
+ * it into a buffer at @a offset. Encoding starts at @a offset and this offset
+ * is moved to the position where the next character can be written to.
+ *
+ * @param ch        Input character.
+ * @param str       Output buffer.
+ * @param offset    Offset (in bytes) where to start writing.
+ * @param sz        Size of the output buffer.
+ *
+ * @return True if the character was encoded successfully or false if there
+ *     was not enough space in the output buffer or the character code
+ *     was invalid.
+ */
+bool chr_encode(const wchar_t ch, char *str, size_t *offset, size_t sz)
+{
+    uint32_t cc;        /* Unsigned version of ch. */
+    int cbytes;     /* Number of continuation bytes. */
+    int b0_bits;        /* Number of data bits in first byte. */
+    int i;
+    if (*offset >= sz)
+        return false;
+    if (ch < 0)
+        return false;
+    /* Bit operations should only be done on unsigned numbers. */
+    cc = (uint32_t) ch;
+    /* Determine how many continuation bytes are needed. */
+    if ((cc & ~LO_MASK_32(7)) == 0) {
+        b0_bits = 7;
+        cbytes = 0;
+    } else if ((cc & ~LO_MASK_32(11)) == 0) {
+        b0_bits = 5;
+        cbytes = 1;
+    } else if ((cc & ~LO_MASK_32(16)) == 0) {
+        b0_bits = 4;
+        cbytes = 2;
+    } else if ((cc & ~LO_MASK_32(21)) == 0) {
+        b0_bits = 3;
+        cbytes = 3;
+    } else {
+        /* Codes longer than 21 bits are not supported. */
+        return false;
+    }
+    /* Check for available space in buffer. */
+    if (*offset + cbytes >= sz)
+        return false;
+    /* Encode continuation bytes. */
+    for (i = cbytes; i > 0; --i) {
+        str[*offset + i] = 0x80 | (cc & LO_MASK_32(CONT_BITS));
+        cc = cc >> CONT_BITS;
+    }
+    /* Encode first byte. */
+    str[*offset] = (cc & LO_MASK_32(b0_bits)) | HI_MASK_8(8 - b0_bits - 1);
+    /* Advance offset. */
+    *offset += (1 + cbytes);
+    return true;
+}
+/** 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;
+    index_t iprev;
+    wchar_t ch;
+    while (true) {
+        iprev = index;
+        if (size >= count)
+            break;
+        ch = chr_decode(str, &index, UTF8_NO_LIMIT);
+        if (ch == '\0') break;
+        size++;
+    }
+    return iprev;
+}
+/** 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 (chr_decode(str, &index, UTF8_NO_LIMIT) != 0) {
+        size++;
+    }
+    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.
  * 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)/branches/dd/kernel/generic/src/lib/string.c @ 4226 – Rev 4055 → 4201