/**
* mds — A micro-display server
* Copyright © 2014, 2015, 2016, 2017 Mattias Andrée (maandree@kth.se)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "string.h"
#include <libmdsserver/macros.h>
#include <stdlib.h>
#include <string.h>
/**
* Get the length of a string
*
* @param string The string
* @return The length of the string
*/
size_t
string_length(const char32_t *restrict string)
{
size_t i = 0;
while (string[i] != -1)
i++;
return i;
}
/**
* Convert a NUL-terminated UTF-8 string to a -1-terminated UTF-32 string
*
* @param string The UTF-8 string
* @return The string in UTF-32, `NULL` on error
*/
char32_t *
string_decode(const char *restrict string)
{
size_t i, j, n, length = 0;
char32_t *rc;
char c;
/* Get the length of the UTF-32 string, excluding termination. */
for (i = 0; string[i]; i++)
if ((string[i] & 0xC0) != 0x80)
length++;
/* Allocated UTF-32 string. */
fail_if (xmalloc(rc, length + 1, char32_t));
/* Convert to UTF-32. */
for (i = j = n = 0; string[i]; i++) {
c = string[i];
if (n) {
rc[j] <<= 6, rc[j] |= c & 0x3F;
if (!--n)
j++;
} else if ((c & 0xC0) == 0xC0) {
while (c & 0x80)
n++, c = (char)(c << 1);
rc[j] = c >> n--;
} else {
rc[j++] = c & 255;
}
}
/* -1-terminate and return. */
return rc[length] = -1, rc;
fail:
return NULL;
}
/**
* Convert a -1-terminated UTF-32 string to a NUL-terminated Modified UTF-8 string
*
* Negative values apart from -1 are converted to 0x00
*
* @param string The UTF-32 string
* @return The string in UTF-8, `NULL` on error
*/
char *
string_encode(const char32_t *restrict string)
{
size_t i, j, n = string_length(string);
char *restrict rc;
char32_t c;
/* Allocated Modified UTF-8 string. */
fail_if (xmalloc(rc, 7 * n + 1, char));
/* Convert to Modified UTF-8. */
for (i = j = 0; i < n; i++) {
#define _c(s) rc[j++] = (char)(((c >> (s)) & 0x3F) | 0x80)
#define _t(s) (0 < c) && ((uint32_t)c < (uint32_t)(1ULL << (s)))
c = string[i];
if (!c) rc[j++] = (char)0xC0, rc[j++] = (char)0x80;
else if (_t( 7)) rc[j++] = (char)c;
else if (_t(11)) rc[j++] = (char)((c >> 6) | 0xC0), _c( 0);
else if (_t(16)) rc[j++] = (char)((c >> 12) | 0xE0), _c( 6), _c( 0);
else if (_t(21)) rc[j++] = (char)((c >> 18) | 0xF0), _c(12), _c( 6), _c( 0);
/* UTF-8 actually ends here, fits 32 planes. */
else if (_t(26)) rc[j++] = (char)((c >> 24) | 0xF8), _c(18), _c(12), _c( 6), _c(0);
else if (_t(31)) rc[j++] = (char)((c >> 30) | 0xFC), _c(24), _c(18), _c(12), _c(6), _c(0);
/* The orginal UTF-8 specification ended here, fits 31 bits.
* However, we added another byte so we can fit 32 bits
* (actually we ca now fit 36 bits.)
* However, we only needed this in `string_decode` which would
* not require any changed, but we added it here for symmetry. */
else rc[j++] = (char)0xFE, _c(30), _c(24), _c(18), _c(12), _c(6), _c(0);
#undef _t
#undef _c
}
/* NUL-terminate and return. */
return rc[j] = '\0', rc;
fail:
return NULL;
}
/**
* Create duplicate of a string
*
* @param string The string
* @return A duplicate of the string, `NULL` on error or if `string` is `NULL`
*/
char32_t *
string_dup(const char32_t *restrict string)
{
size_t n;
char32_t *rc;
if (!string)
return NULL;
n = string_length(string) + 1;
fail_if (xmemdup(rc, string, n, char32_t));
return rc;
fail:
return NULL;
}
