/*-
 * Copyright (c) 2008 Ariff Abdullah <ariff@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.
 *
 *        $FreeBSD$
 */

static __inline int32_t
vseg(int32_t v, int32_t o)
{
	int32_t r;

	r = o;
	v >>= 7;
	v >>= o;
	if (v & 0xf0) {
		v >>= 4;
		r += 4;
	}
	if (v & 0x0c) {
		v >>= 2;
		r += 2;
	}
	if (v & 0x02)
		r++;
	
	return (r);
}

static intpcm_t
alaw_to_intpcm(uint8_t v)
{
	int32_t s, t;

	v ^= 0x55;
	t = v & 0x7f;
	if (t < 0x10)
		t = (t << 4) + 8;
	else {
		s = (t >> 4) & 0x07;
		t = ((t & 0x0f) << 4) + 0x108;
		t <<= s - 1;
	}

	return (((v & 0x80) ? t : -t) << 16);
}

static uint8_t
intpcm_to_alaw(intpcm_t v)
{
	int32_t m, s;
	uint8_t a;

	v >>= 16;
	if (v >= 0)
		m = 0xd5;
	else {
		m = 0x55;
		v = -v;
		if (v > 0x7fff)
			v = 0x7fff;
	}

	if (v < 0x100)
		a = v >> 4;
	else {
		s = vseg(v, 1);
		a = (s << 4) | ((v >> (s + 3)) & 0x0f);
	}

	return (a ^ m);
}

static intpcm_t
ulaw_to_intpcm(uint8_t v)
{
	int32_t t;

	v = ~v;
	t = ((v & 0x0f) << 3) + 0x84;
	t <<= (v & 0x70) >> 4;

	return (((v & 0x80) ? (0x80 - t) : (t - 0x84)) << 16);
}

static uint8_t
intpcm_to_ulaw(intpcm_t v)
{
	int32_t m, s;
	uint8_t u;

	v >>= 16;
	if (v < 0) {
		v = 0x84 - v;
		m = 0x7f;
	} else {
		v += 0x84;
		m = 0xff;
	}
	
	if (v > 0x7fff)
		v = 0x7fff;

	s = vseg(v, 0);
	u = (s << 4) | ((v >> (s + 3)) & 0x0f);

	return (u ^ m);
}