/*      $NetBSD: buffer.h,v 1.5 2017/10/13 00:11:56 christos Exp $      */

/*-
 * Copyright (c) 2005 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christos Zoulas.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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.
 */

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
#include <err.h>

#define BUF_SIZE        BUFSIZ
struct buffer {
        wchar_t *ptr;
        wchar_t *bptr;
        wchar_t *eptr;
};

static void
buf_init(struct buffer *buf)
{
        buf->ptr = buf->bptr = calloc(BUF_SIZE, sizeof(*buf->ptr));
        if (buf->ptr == NULL)
                err(1, "Cannot allocate buffer");
        buf->eptr = buf->ptr + BUF_SIZE;
}

static void
buf_end(struct buffer *buf)
{
        free(buf->bptr);
}

static void
buf_grow(struct buffer *buf, size_t minsize)
{
        ptrdiff_t diff;
        size_t len = (buf->eptr - buf->bptr) + 
            (minsize > BUF_SIZE ? minsize : BUF_SIZE);
        wchar_t *nptr = realloc(buf->bptr, len * sizeof(*buf->ptr));

        if (nptr == NULL)
                err(1, "Cannot grow buffer");

        if (nptr == buf->bptr) {
                buf->eptr = buf->bptr + len;
                return;
        }

        diff = nptr - buf->bptr;
        buf->bptr += diff;
        buf->eptr = buf->bptr + len;
        buf->ptr += diff;
}

static inline void
buf_putc(struct buffer *buf, wchar_t c)
{
        if (buf->ptr >= buf->eptr)
                buf_grow(buf, 1);
        *buf->ptr++ = c;
}

static inline void
buf_reset(struct buffer *buf)
{
        buf->ptr = buf->bptr;
}

static inline wchar_t 
buf_unputc(struct buffer *buf)
{
        return buf->ptr > buf->bptr ? *--buf->ptr : '\0';
}