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/*
 * Copyright (c) 2006 Josef Cejka
 * 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
 */

#include <print.h>
#include <printf/printf_core.h>
#include <string.h>
#include <memstr.h>

typedef struct {
    size_t size;    /* Total size of the buffer (in bytes) */
    size_t len;     /* Number of already used bytes */
    char *dst;      /* Destination */
} vsnprintf_data_t;

/** Write UTF-8 string to given buffer.
 *
 * Write at most data->size plain characters including trailing zero.
 * According to C99, snprintf() has to return number of characters that
 * would have been written if enough space had been available. Hence
 * the return value is not the number of actually printed characters
 * but size of the input string.
 *
 * @param str  Source UTF-8 string to print.
 * @param size Number of plain characters in str.
 * @param data Structure describing destination string, counter
 *             of used space and total string size.
 *
 * @return Number of UTF-8 characters to print (not characters actually
 *         printed).
 *
 */
static int vsnprintf_write_utf8(const char *str, size_t size, vsnprintf_data_t *data)
{
    size_t left = data->size - data->len;
    
    if (left == 0)
        return ((int) size);
    
    if (left == 1) {
        /* We have only one free byte left in buffer
         * -> store trailing zero
         */
        data->dst[data->size - 1] = 0;
        data->len = data->size;
        return ((int) size);
    }
    
    if (left <= size) {
        /* We have not enought space for whole string
         * with the trailing zero => print only a part
         * of string
         */
        index_t index = 0;
        
        while (index < size) {
            wchar_t uc = chr_decode(str, &index, size);

            if (!chr_encode(uc, data->dst, &data->len, data->size - 1))
                break;
        }
        
        /* Put trailing zero at end, but not count it
         * into data->len so it could be rewritten next time
         */
        data->dst[data->len] = 0;
        
        return ((int) size);
    }
    
    /* Buffer is big enought to print the whole string */
    memcpy((void *)(data->dst + data->len), (void *) str, size);
    data->len += size;
    
    /* Put trailing zero at end, but not count it
     * into data->len so it could be rewritten next time
     */
    data->dst[data->len] = 0;
    
    return ((int) size);
}

/** Write UTF-32 string to given buffer.
 *
 * Write at most data->size plain characters including trailing zero.
 * According to C99, snprintf() has to return number of characters that
 * would have been written if enough space had been available. Hence
 * the return value is not the number of actually printed characters
 * but size of the input string.
 *
 * @param str  Source UTF-32 string to print.
 * @param size Number of bytes in str.
 * @param data Structure describing destination string, counter
 *             of used space and total string size.
 *
 * @return Number of UTF-8 characters to print (not characters actually
 *         printed).
 *
 */
static int vsnprintf_write_utf32(const wchar_t *str, size_t size, vsnprintf_data_t *data)
{
    index_t index = 0;
    
    while (index < (size / sizeof(wchar_t))) {
        size_t left = data->size - data->len;
        
        if (left == 0)
            return ((int) size);
        
        if (left == 1) {
            /* We have only one free byte left in buffer
             * -> store trailing zero
             */
            data->dst[data->size - 1] = 0;
            data->len = data->size;
            return ((int) size);
        }
        
        if (!chr_encode(str[index], data->dst, &data->len, data->size - 1))
            break;
        
        index++;
    }
    
    /* Put trailing zero at end, but not count it
     * into data->len so it could be rewritten next time
     */
    data->dst[data->len] = 0;
    
    return ((int) size);
}

int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
{
    vsnprintf_data_t data = {
        size,
        0,
        str
    };
    printf_spec_t ps = {
        (int(*) (const char *, size_t, void *)) vsnprintf_write_utf8,
        (int(*) (const wchar_t *, size_t, void *)) vsnprintf_write_utf32,
        &data
    };
    
    /* Print 0 at end of string - fix the case that nothing will be printed */
    if (size > 0)
        str[0] = 0;
    
    /* vsnprintf_write ensures that str will be terminated by zero. */
    return printf_core(fmt, &ps, ap);
}

/** @}
 */