/*-
 * Copyright (c) 2008 Wojciech A. Koszek <wkoszek@FreeBSD.org>
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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.
 *
 * [id for your version control system, if any]
 */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Assumptions
 *
 * Some characters within TTYs carry additional flags like "quoted",
 * "typical", "whitespace" etc.
 *
 * TTYs already have a notion of those flags.
 *
 * Instead
 *   
 * Consider manipulation of flag/character separately--for a given
 * integer:
 *
 * 	0x####@@@@
 *
 * representing a character, make:
 *
 *   	cbuf_putc(cb, @) 
 *
 * Put 0x0000@@@@ valua in cbuf, while:
 *
 *   	cbuf_fputc(cb, @, #)
 *
 * would put:
 *
 *       0x####@@@@
 *
 *
 */

/*
 * Inserting/getting byte-stream from/to cbuf to be done.
 */

struct cbuf {
#define	CBUF_MAGIC0	0x12345678
	unsigned	 cbuf_magic0;
#define CBUF_INIT(c)	((c)->cbuf_magic0 = CBUF_MAGIC0)
#define CBUF_ASSERT(c)	assert((c)->cbuf_magic0 == CBUF_MAGIC0)

	int		*b;
	int		*e;
	int		*p;
};

static struct cbuf *
cbuf_alloc(size_t bufsize)
{
	struct cbuf *r;
	int *mem;

	r = calloc(1, sizeof(*r));
	assert(r != NULL);
	CBUF_INIT(r);

	mem = calloc(sizeof(*r->b), bufsize);
	assert(mem != NULL);

	r->b = mem;
	r->p = mem;
	r->e = mem + bufsize;

	CBUF_ASSERT(r);
	return (r);
}

static void
cbuf_free(struct cbuf *cb)
{

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	free(cb->b);
}

static int
cbuf_isempty(struct cbuf *cb)
{

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	return (cb->p == cb->b);
}

static int
cbuf_full(struct cbuf *cb)
{

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	return (cb->p == cb->e);
}

static int
cbuf_putc(struct cbuf *cb, int c)
{

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	if (cb->p == cb->e)
		return (-1);
	cb->p++;
	*cb->p = c;
	return (0);
}

static int
cbuf_getc(struct cbuf *cb)
{
	int r;

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	r = *cb->p;
	cb->p--;
	return (r);
}

static void
cbuf_clear(struct cbuf *cb)
{

	assert(cb != NULL);
	CBUF_ASSERT(cb);
	memset(cb->b, 0, cb->e - cb->b);
	cb->p = cb->b;
}

static int
cbuf_cmp(struct cbuf *cb0, struct cbuf *cb1)
{
	int l0, l1;

	assert(cb0 != NULL);
	assert(cb1 != NULL);
	CBUF_ASSERT(cb0);
	CBUF_ASSERT(cb1);

	l0 = cb0->e - cb0->b;
	l1 = cb1->e - cb1->b;

	if (l0 != l1)
		return (-1);

	return (memcmp(cb0->b, cb1->b, l0));
}

static int
cbuf_equal(struct cbuf *cb0, struct cbuf *cb1)
{

	return (!cbuf_cmp(cb0, cb1));
}

static void
CB_TestEmpty(void)
{
	struct cbuf *cb;
	int e;

	cb = cbuf_alloc(1024);
	e = cbuf_isempty(cb);
	assert(e == 1);
	cbuf_free(cb);
}

static void
CB_TestPutGet(void)
{
	struct cbuf *cb;
	int e;

	cb = cbuf_alloc(10);
	assert(cb);
	CBUF_ASSERT(cb);
	e = cbuf_putc(cb, 'W');
	assert(e == 0);
	e = cbuf_getc(cb);
	assert(e == 'W');
	cbuf_free(cb);


	cb = cbuf_alloc(10);
	assert(cb);
	CBUF_ASSERT(cb);
	e = cbuf_putc(cb, 'W');
	assert(e == 0);
	e = cbuf_putc(cb, 'A');
	assert(e == 0);
	e = cbuf_putc(cb, 'K');
	assert(e == 0);

	e = cbuf_getc(cb);
	assert(e == 'K');
	
	e = cbuf_getc(cb);
	assert(e == 'A');

	e = cbuf_getc(cb);
	assert(e == 'W');

	cbuf_free(cb);
}

static void
CB_TestFull(void)
{
	struct cbuf *cb;
	int e, i;

	cb = cbuf_alloc(1024);
	for (i = 0; i < 1024; i++) {
		e = cbuf_putc(cb, i);
		assert(e == 0);
	}
	e = cbuf_full(cb);
	assert(e == 1 && "cbuf_full(cb)");
}

static void
CB_TestClear(void)
{
	struct cbuf *cb;
	int e, i;

	cb = cbuf_alloc(1000);
	for (i = 0; i < 1000; i++)
		cbuf_putc(cb, i);
	e = cbuf_full(cb);
	assert(e == 1 && "cbuf_full(cb)");

	cbuf_clear(cb);
	e = cbuf_isempty(cb);
	assert(e == 1 && "cbuf_isempty(cb)");
}

static void
CB_TestCmp(void)
{
	char test[] = "CB_TestCMP";
	struct cbuf *c0;
	struct cbuf *c1;
	int sz;
	int e;
	int i;

	sz = sizeof(test);

	c0 = cbuf_alloc(sz);
	c1 = cbuf_alloc(sz);
	cbuf_clear(c0);
	cbuf_clear(c1);
	for (i = 0; i < sz; i++) {
		cbuf_putc(c0, test[i]);
		cbuf_putc(c1, test[i]);
	}

	e = cbuf_cmp(c0, c1);
	assert(e == 0 && "cbuf_cmp(c0, c1)");

	e = cbuf_equal(c0, c1);
	assert(e == 1 && "cbuf_equal(c0, c1)");
}


int
main(int argc __unused, char **argv __unused)
{

	CB_TestEmpty();
	CB_TestPutGet();
	CB_TestFull();
	CB_TestClear();
	CB_TestCmp();

	exit(EXIT_SUCCESS);
}