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/*

 * 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 String functions.

 *

 * Strings and characters use the Universal Character Set (UCS). The standard

 * strings, called just strings are encoded in UTF-8. Wide strings (encoded

 * in UTF-32) are supported to a limited degree. A single character is

 * represented as wchar_t.

 *

 * Strings have the following metrics:

 *

 *  Metric  Abbrev. Meaning

 *  ------  ------  -------

 *  size    n   Number of bytes the string is encoded into, excluding

 *          the null terminator.

 *  length  l   The number of characters in the string, excluding

 *          the null terminator.

 *  width   w   The number of character cells the string takes up on a

 *          monospace display.

 *

 * Naming scheme:

 *

 *  chr_xxx     operate on characters

 *  str_xxx     operate on strings

 *  wstr_xxx    operate on wide strings

 *

 *  [w]str_[n|l|w]xxx   operate on a prefix limited by size, length

 *              or width.

 */

#include <string.h>

#include <print.h>

#include <cpu.h>

#include <arch/asm.h>

#include <arch.h>

#include <errno.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

/** 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 EOK if the character was encoded successfully, EOVERFLOW if there

 *     was not enough space in the output buffer or EINVAL if the character

 *     code was invalid.

 */

int chr_encode(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 EOVERFLOW;

    if (ch < 0)

        return EINVAL;

    /* 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 EINVAL;

    }

    /* Check for available space in buffer. */

    if (*offset + cbytes >= sz)

        return EOVERFLOW;

    /* 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 EOK;

}

/** Get display width of character.

 *

 * @param ch    The character.

 * @return  Character width in display cells.

 */

count_t chr_width(wchar_t ch)

{

    return 1;

}

/** Get size of string, with length limit.

 *

 * Get the number of bytes which are used by up to @a max_len first

 * characters in the string @a str. If @a max_len is greater than

 * the length of @a str, the entire string is measured.

 *

 * @param str   String to consider.

 * @param count Maximum number of characters to measure.

 *

 * @return  Number of bytes used by the characters.

 */

size_t str_lsize(const char *str, count_t max_len)

{

    count_t len = 0;

    size_t cur = 0;

    size_t prev;

    wchar_t ch;

    while (true) {

        prev = cur;

        if (len >= max_len)

            break;

        ch = chr_decode(str, &cur, UTF8_NO_LIMIT);

        if (ch == '\0') break;

        len++;

    }

    return prev;

}

/** Get size of string, with width limit.

 *

 * Get the number of bytes which are used by the longest prefix of @a str

 * that can fit into @a max_width display cells.

 *

 * @param str   String to consider.

 * @param count Maximum number of display cells.

 *

 * @return  Number of bytes used by the characters that fit.

 */

size_t str_wsize(const char *str, count_t max_width)

{

    count_t width = 0;

    size_t cur = 0;

    size_t prev;

    wchar_t ch;

    while (true) {

        prev = cur;

        if (width >= max_width)

            break;

        ch = chr_decode(str, &cur, UTF8_NO_LIMIT);

        if (ch == '\0') break;

        width += chr_width(ch);

    }

    return prev;

}

/** Get length of wide string, with width limit.

 *

 * Get the number of characters in a wide string that can fit into @a max_width

 * display cells.

 *

 * @param wstr   Wide string to consider.

 * @param count Maximum number of display cells.

 *

 * @return  Number of bytes used by the characters that fit.

 */

count_t wstr_wlength(const wchar_t *wstr, count_t max_width)

{

    count_t width = 0;

    index_t cur = 0;

    while (true) {

        if (width >= max_width)

            break;

        if (wstr[cur] == '\0') break;

        width += chr_width(wstr[cur]);

        ++cur;

    }

    return (count_t) cur;

}

/** 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 bytes the string occupies.

 *

 * @param str A string.

 * @return Number of bytes in @a str excluding the null terminator.

 */

size_t str_size(const char *str)

{

    size_t size;

    size = 0;

    while (*str++ != '\0')

        ++size;

    return size;

}

/** Return number of characters in a string.

 *

 * @param str NULL-terminated string.

 * @return Number of characters in string.

 */

count_t str_length(const char *str)

{

    count_t len = 0;

    size_t offset = 0;

    while (chr_decode(str, &offset, UTF8_NO_LIMIT) != 0) {

        len++;

    }

    return len;

}

/** Return number of characters in a wide string.

 *

 * @param   str NULL-terminated wide string.

 * @return  Number of characters in @a str.

 */

count_t wstr_length(const wchar_t *wstr)

{

    count_t len;

    len = 0;

    while (*wstr++ != '\0')

        ++len;

    return len;

}

/** 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;

}

/** @}

 */