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Ignore whitespace Rev 4347 → Rev 4348

/branches/dynload/kernel/generic/src/lib/string.c
32,7 → 32,73
 
/**
* @file
* @brief Miscellaneous functions.
* @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.@n
*
* Overview of the terminology:@n
*
* Term Meaning
* -------------------- ----------------------------------------------------
* byte 8 bits stored in uint8_t (unsigned 8 bit integer)
*
* character UTF-32 encoded Unicode character, stored in wchar_t
* (signed 32 bit integer), code points 0 .. 1114111
* are valid
*
* ASCII character 7 bit encoded ASCII character, stored in char
* (usually signed 8 bit integer), code points 0 .. 127
* are valid
*
* string UTF-8 encoded NULL-terminated Unicode string, char *
*
* wide string UTF-32 encoded NULL-terminated Unicode string,
* wchar_t *
*
* [wide] string size number of BYTES in a [wide] string (excluding
* the NULL-terminator), size_t
*
* [wide] string length number of CHARACTERS in a [wide] string (excluding
* the NULL-terminator), count_t
*
* [wide] string width number of display cells on a monospace display taken
* by a [wide] string, count_t
*
*
* Overview of string metrics:@n
*
* Metric Abbrev. Type Meaning
* ------ ------ ------ -------------------------------------------------
* size n size_t number of BYTES in a string (excluding the
* NULL-terminator)
*
* length l count_t number of CHARACTERS in a string (excluding the
* null terminator)
*
* width w count_t number of display cells on a monospace display
* taken by a string
*
*
* Function naming prefixes:@n
*
* chr_ operate on characters
* ascii_ operate on ASCII characters
* str_ operate on strings
* wstr_ operate on wide strings
*
* [w]str_[n|l|w] operate on a prefix limited by size, length
* or width
*
*
* A specific character inside a [wide] string can be referred to by:@n
*
* pointer (char *, wchar_t *)
* byte offset (size_t)
* character index (count_t)
*
*/
 
#include <string.h>
40,378 → 106,607
#include <cpu.h>
#include <arch/asm.h>
#include <arch.h>
#include <console/kconsole.h>
#include <errno.h>
#include <align.h>
#include <debug.h>
 
char invalch = '?';
/** Byte mask consisting of lowest @n bits (out of 8) */
#define LO_MASK_8(n) ((uint8_t) ((1 << (n)) - 1))
 
/** Decode a single UTF-8 character from a NULL-terminated string.
/** 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 8) */
#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 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.
* Decode a single character from a string of size @a size. 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 size.
*
* @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.
* @param str String (not necessarily NULL-terminated).
* @param offset Byte offset in string where to start decoding.
* @param size Size of the string (in bytes).
*
* @return Decoded character in UTF-32 or '?' if the encoding is wrong.
* @return Value of decoded character, U_SPECIAL on decoding error or
* NULL if attempt to decode beyond @a size.
*
*/
wchar_t utf8_decode(const char *str, index_t *index, index_t limit)
wchar_t str_decode(const char *str, size_t *offset, size_t size)
{
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 (*offset + 1 > size)
return 0;
if (*index > limit)
return invalch;
/* First byte read from string */
uint8_t b0 = (uint8_t) str[(*offset)++];
c1 = (uint8_t) str[*index];
/* Determine code length */
if ((c1 & 0x80) == 0) {
/* Plain ASCII (code points 0 .. 127) */
return (wchar_t) c1;
}
unsigned int b0_bits; /* Data bits in first byte */
unsigned int cbytes; /* Number of continuation bytes */
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 ((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 U_SPECIAL;
}
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 (*offset + cbytes > size)
return U_SPECIAL;
if ((c1 & 0xf8) == 0xf0) {
/* Code points 65536 .. 1114111 */
if (*index + 3 > limit)
return invalch;
wchar_t ch = b0 & LO_MASK_8(b0_bits);
/* Decode continuation bytes */
while (cbytes > 0) {
uint8_t b = (uint8_t) str[(*offset)++];
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;
/* Must be 10xxxxxx */
if ((b & 0xc0) != 0x80)
return U_SPECIAL;
/* Shift data bits to ch */
ch = (ch << CONT_BITS) | (wchar_t) (b & LO_MASK_8(CONT_BITS));
cbytes--;
}
return invalch;
return ch;
}
 
/** Encode a single UTF-32 character as UTF-8
/** Encode a single character to string representation.
*
* 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.
* 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 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.
* @param ch Input character.
* @param str Output buffer.
* @param offset Byte offset where to start writing.
* @param size Size of the output buffer (in bytes).
*
* @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.
*
* @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.
*/
bool utf8_encode(const wchar_t ch, char *str, index_t *index, index_t limit)
int chr_encode(wchar_t ch, char *str, size_t *offset, size_t size)
{
if (*index > limit)
return false;
if (*offset >= size)
return EOVERFLOW;
if ((ch >= 0) && (ch <= 127)) {
/* Plain ASCII (code points 0 .. 127) */
str[*index] = ch & 0x7f;
return true;
}
if (!chr_check(ch))
return EINVAL;
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;
}
/* Unsigned version of ch (bit operations should only be done
on unsigned types). */
uint32_t cc = (uint32_t) ch;
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;
/* Determine how many continuation bytes are needed */
unsigned int b0_bits; /* Data bits in first byte */
unsigned int cbytes; /* Number of continuation bytes */
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;
}
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;
/* Check for available space in buffer */
if (*offset + cbytes >= size)
return EOVERFLOW;
/* Encode continuation bytes */
unsigned int i;
for (i = cbytes; i > 0; i--) {
str[*offset + i] = 0x80 | (cc & LO_MASK_32(CONT_BITS));
cc = cc >> CONT_BITS;
}
return false;
/* Encode first byte */
str[*offset] = (cc & LO_MASK_32(b0_bits)) | HI_MASK_8(8 - b0_bits - 1);
/* Advance offset */
*offset += cbytes + 1;
return EOK;
}
 
/** Get bytes used by UTF-8 characters.
/** Get size of string.
*
* 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.
* Get the number of bytes which are used by the string @a str (excluding the
* NULL-terminator).
*
* @param str UTF-8 string to consider.
* @param count Number of UTF-8 characters to count.
* @param str String to consider.
*
* @return Number of bytes used by the characters.
* @return Number of bytes used by the string
*
*/
size_t utf8_count_bytes(const char *str, count_t count)
size_t str_size(const char *str)
{
size_t size = 0;
index_t index = 0;
while ((utf8_decode(str, &index, UTF8_NO_LIMIT) != 0) && (size < count)) {
while (*str++ != 0)
size++;
index++;
return size;
}
 
/** Get size of wide string.
*
* Get the number of bytes which are used by the wide string @a str (excluding the
* NULL-terminator).
*
* @param str Wide string to consider.
*
* @return Number of bytes used by the wide string
*
*/
size_t wstr_size(const wchar_t *str)
{
return (wstr_length(str) * sizeof(wchar_t));
}
 
/** 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 (excluding the
* NULL-terminator).
*
* @param str String to consider.
* @param max_len 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 offset = 0;
while (len < max_len) {
if (str_decode(str, &offset, STR_NO_LIMIT) == 0)
break;
len++;
}
return index;
return offset;
}
 
/** Check whether character is plain ASCII.
/** Get size of wide string with length limit.
*
* @return True if character is plain ASCII.
* Get the number of bytes which are used by up to @a max_len first
* wide characters in the wide string @a str. If @a max_len is greater than
* the length of @a str, the entire wide string is measured (excluding the
* NULL-terminator).
*
* @param str Wide string to consider.
* @param max_len Maximum number of wide characters to measure.
*
* @return Number of bytes used by the wide characters.
*
*/
bool ascii_check(const wchar_t ch)
size_t wstr_lsize(const wchar_t *str, count_t max_len)
{
if ((ch >= 0) && (ch <= 127))
return true;
return (wstr_nlength(str, max_len * sizeof(wchar_t)) * sizeof(wchar_t));
}
 
/** Get 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;
return false;
while (str_decode(str, &offset, STR_NO_LIMIT) != 0)
len++;
return len;
}
 
/** Check whether character is Unicode.
/** Get number of characters in a wide string.
*
* @return True if character is valid Unicode code point.
* @param str NULL-terminated wide string.
*
* @return Number of characters in @a str.
*
*/
bool unicode_check(const wchar_t ch)
count_t wstr_length(const wchar_t *wstr)
{
if ((ch >= 0) && (ch <= 1114111))
return true;
count_t len = 0;
return false;
while (*wstr++ != 0)
len++;
return len;
}
 
/** Return number of plain characters in a string.
/** Get number of characters in a string with size limit.
*
* @param str NULL-terminated string.
* @param str NULL-terminated string.
* @param size Maximum number of bytes to consider.
*
* @return Number of characters in str.
* @return Number of characters in string.
*
*/
size_t strlen(const char *str)
count_t str_nlength(const char *str, size_t size)
{
size_t size;
for (size = 0; str[size]; size++);
count_t len = 0;
size_t offset = 0;
return size;
while (str_decode(str, &offset, size) != 0)
len++;
return len;
}
 
/** Return number of UTF-8 characters in a string.
/** Get number of characters in a string with size limit.
*
* @param str NULL-terminated UTF-8 string.
* @param str NULL-terminated string.
* @param size Maximum number of bytes to consider.
*
* @return Number of UTF-8 characters in str.
* @return Number of characters in string.
*
*/
size_t strlen_utf8(const char *str)
count_t wstr_nlength(const wchar_t *str, size_t size)
{
size_t size = 0;
index_t index = 0;
count_t len = 0;
count_t limit = ALIGN_DOWN(size, sizeof(wchar_t));
count_t offset = 0;
while (utf8_decode(str, &index, UTF8_NO_LIMIT) != 0) {
size++;
index++;
while ((offset < limit) && (*str++ != 0)) {
len++;
offset += sizeof(wchar_t);
}
return size;
return len;
}
 
/** Return number of UTF-32 characters in a string.
/** Check whether character is plain ASCII.
*
* @param str NULL-terminated UTF-32 string.
* @return True if character is plain ASCII.
*
* @return Number of UTF-32 characters in str.
*/
bool ascii_check(wchar_t ch)
{
if ((ch >= 0) && (ch <= 127))
return true;
return false;
}
 
/** Check whether character is valid
*
* @return True if character is a valid Unicode code point.
*
*/
size_t strlen_utf32(const wchar_t *str)
bool chr_check(wchar_t ch)
{
size_t size;
for (size = 0; str[size]; size++);
if ((ch >= 0) && (ch <= 1114111))
return true;
return size;
return false;
}
 
/** Compare two NULL terminated strings
/** Compare two NULL terminated strings.
*
* Do a char-by-char comparison of 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.
* @param s1 First string to compare.
* @param s2 Second string to compare.
*
* @return 0 if the strings are equal, -1 if first is smaller, 1 if second smaller.
* @return 0 if the strings are equal, -1 if first is smaller,
* 1 if second smaller.
*
*/
int strcmp(const char *src, const char *dst)
int str_cmp(const char *s1, const char *s2)
{
for (; *src && *dst; src++, dst++) {
if (*src < *dst)
wchar_t c1 = 0;
wchar_t c2 = 0;
size_t off1 = 0;
size_t off2 = 0;
 
while (true) {
c1 = str_decode(s1, &off1, STR_NO_LIMIT);
c2 = str_decode(s2, &off2, STR_NO_LIMIT);
 
if (c1 < c2)
return -1;
if (*src > *dst)
if (c1 > c2)
return 1;
 
if (c1 == 0 || c2 == 0)
break;
}
if (*src == *dst)
return 0;
if (!*src)
return -1;
return 1;
 
return 0;
}
 
 
/** Compare two NULL terminated strings
/** Compare two NULL terminated strings with length limit.
*
* Do a char-by-char comparison of 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.
* characters on the minimum of their lengths and the length limit.
*
* @param src First string to compare.
* @param dst Second string to compare.
* @param len Maximal length for comparison.
* @param s1 First string to compare.
* @param s2 Second string to compare.
* @param max_len Maximum number of characters to consider.
*
* @return 0 if the strings are equal, -1 if first is smaller, 1 if second smaller.
* @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)
int str_lcmp(const char *s1, const char *s2, count_t max_len)
{
unsigned int i;
wchar_t c1 = 0;
wchar_t c2 = 0;
for (i = 0; (*src) && (*dst) && (i < len); src++, dst++, i++) {
if (*src < *dst)
size_t off1 = 0;
size_t off2 = 0;
count_t len = 0;
 
while (true) {
if (len >= max_len)
break;
 
c1 = str_decode(s1, &off1, STR_NO_LIMIT);
c2 = str_decode(s2, &off2, STR_NO_LIMIT);
 
if (c1 < c2)
return -1;
if (*src > *dst)
 
if (c1 > c2)
return 1;
 
if (c1 == 0 || c2 == 0)
break;
 
++len;
}
 
return 0;
 
}
 
/** Copy string.
*
* Copy source string @a src to destination buffer @a dest.
* No more than @a size bytes are written. If the size of the output buffer
* is at least one byte, the output string will always be well-formed, i.e.
* null-terminated and containing only complete characters.
*
* @param dst Destination buffer.
* @param count Size of the destination buffer (must be > 0).
* @param src Source string.
*/
void str_cpy(char *dest, size_t size, const char *src)
{
wchar_t ch;
size_t src_off;
size_t dest_off;
 
/* There must be space for a null terminator in the buffer. */
ASSERT(size > 0);
if (i == len || *src == *dst)
return 0;
if (!*src)
return -1;
return 1;
src_off = 0;
dest_off = 0;
 
while ((ch = str_decode(src, &src_off, STR_NO_LIMIT)) != 0) {
if (chr_encode(ch, dest, &dest_off, size - 1) != EOK)
break;
}
 
dest[dest_off] = '\0';
}
 
/** Copy size-limited substring.
*
* Copy prefix of string @a src of max. size @a size to destination buffer
* @a dest. No more than @a size bytes are written. The output string will
* always be well-formed, i.e. null-terminated and containing only complete
* characters.
*
* No more than @a n bytes are read from the input string, so it does not
* have to be null-terminated.
*
* @param dst Destination buffer.
* @param count Size of the destination buffer (must be > 0).
* @param src Source string.
* @param n Maximum number of bytes to read from @a src.
*/
void str_ncpy(char *dest, size_t size, const char *src, size_t n)
{
wchar_t ch;
size_t src_off;
size_t dest_off;
 
/* There must be space for a null terminator in the buffer. */
ASSERT(size > 0);
src_off = 0;
dest_off = 0;
 
/** Copy NULL terminated string.
while ((ch = str_decode(src, &src_off, n)) != 0) {
if (chr_encode(ch, dest, &dest_off, size - 1) != EOK)
break;
}
 
dest[dest_off] = '\0';
}
 
/** Copy NULL-terminated wide string to 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.
* Copy source wide string @a src to destination buffer @a dst.
* No more than @a size bytes are written. NULL-terminator is always
* written after the last succesfully copied character (i.e. if the
* destination buffer is has at least 1 byte, it will be always
* NULL-terminated).
*
* @param src Source string.
* @param dest Destination buffer.
* @param len Size of destination buffer.
* @param src Source wide string.
* @param dst Destination buffer.
* @param count Size of the destination buffer.
*
*/
void strncpy(char *dest, const char *src, size_t len)
void wstr_nstr(char *dst, const wchar_t *src, size_t size)
{
unsigned int i;
/* No space for the NULL-terminator in the buffer */
if (size == 0)
return;
for (i = 0; i < len; i++) {
if (!(dest[i] = src[i]))
return;
wchar_t ch;
count_t src_idx = 0;
size_t dst_off = 0;
while ((ch = src[src_idx++]) != 0) {
if (chr_encode(ch, dst, &dst_off, size) != EOK)
break;
}
dest[i - 1] = '\0';
if (dst_off >= size)
dst[size - 1] = 0;
else
dst[dst_off] = 0;
}
 
/** Find first occurence of character in string.
*
* @param s String to search.
* @param i Character to look for.
* @param str String to search.
* @param ch Character to look for.
*
* @return Pointer to character in @a s or NULL if not found.
* @return Pointer to character in @a str or NULL if not found.
*
*/
extern char *strchr(const char *s, int i)
const char *str_chr(const char *str, wchar_t ch)
{
while (*s != '\0') {
if (*s == i)
return (char *) s;
++s;
wchar_t acc;
size_t off = 0;
size_t last = 0;
while ((acc = str_decode(str, &off, STR_NO_LIMIT)) != 0) {
if (acc == ch)
return (str + last);
last = off;
}
return NULL;
}
 
/** Insert a wide character into a wide string.
*
* Insert a wide character into a wide string at position
* @a pos. The characters after the position are shifted.
*
* @param str String to insert to.
* @param ch Character to insert to.
* @param pos Character index where to insert.
@ @param max_pos Characters in the buffer.
*
* @return True if the insertion was sucessful, false if the position
* is out of bounds.
*
*/
bool wstr_linsert(wchar_t *str, wchar_t ch, count_t pos, count_t max_pos)
{
count_t len = wstr_length(str);
if ((pos > len) || (pos + 1 > max_pos))
return false;
count_t i;
for (i = len; i + 1 > pos; i--)
str[i + 1] = str[i];
str[pos] = ch;
return true;
}
 
/** Remove a wide character from a wide string.
*
* Remove a wide character from a wide string at position
* @a pos. The characters after the position are shifted.
*
* @param str String to remove from.
* @param pos Character index to remove.
*
* @return True if the removal was sucessful, false if the position
* is out of bounds.
*
*/
bool wstr_remove(wchar_t *str, count_t pos)
{
count_t len = wstr_length(str);
if (pos >= len)
return false;
count_t i;
for (i = pos + 1; i <= len; i++)
str[i - 1] = str[i];
return true;
}
 
/** @}
*/