/*-
 * vim:sw=2 ts=8:noet nosta:fdm=marker
 *
 *
 * Copyright (c) 2014 Ariff Abdullah <ariff@siagalabs.com>
 * 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.
 *
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/endian.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <err.h>

typedef int32_t intpcm_t;

#define INTPCM_T(v)	((intpcm_t)(v))
#define PCM_S32_MAX	0x7fffffff
#define PCM_S32_MIN	(-0x7fffffff - 1)

/***
 *** BEWARE OF STRICT ALIASING *** BEWARE OF STRICT ALIASING
 ***/

#undef SND_IEEE754_OE
#define	SND_IEEE754_OE

static __inline intpcm_t
intpcm_read_ieee754_32ne(uint8_t *src)
{
	uint32_t v;
	int32_t s, e, m;

	v = *((uint32_t *)src);

	e = (v >> 23) & 0xff;

	/* NaN, +/- Inf  or too small */
	if (e == 0xff || e < 96)
		return (INTPCM_T(0));

	s = ((v & 0x80000000U) != 0) ? 1 : 0;

	if (e > 126)
		return (INTPCM_T((s == 0) ? PCM_S32_MAX : PCM_S32_MIN));

	m = 0x800000 | (v & 0x7fffff);
	e += 8 - 127;

	if (e < 0)
		m >>= -e;
	else
		m <<= e;

	return (INTPCM_T((s == 0) ? m : -m));
}

static __inline void
intpcm_write_ieee754_32ne(uint8_t *dst, intpcm_t v)
{
	uint32_t r;
	int32_t e;

	if (v == 0)
		r = 0;
	else if (v == PCM_S32_MAX)
		r = 0x3f800000;
	else if (v == PCM_S32_MIN)
		r = 0x80000000U | 0x3f800000; 
	else {
		r = 0;
		if (v < 0) {
			r |= 0x80000000U;
			v = -v;
		}
	
		e = 127 - 8;
		while ((v & 0x7f000000) != 0) {
			v >>= 1;
			e++;
		}
		while ((v & 0x7f800000) == 0) {
			v <<= 1;
			e--;
		}
	
		r |= (e & 0xff) << 23;
		r |= v & 0x7fffff;
	}

	*((uint32_t *)dst) = r;
}

#define	intpcm_read_float	intpcm_read_ieee754_32ne
#define	intpcm_write_float	intpcm_write_ieee754_32ne

#ifdef SND_IEEE754_OE
static __inline intpcm_t
intpcm_read_ieee754_32oe(uint8_t *src)
{
#if 1
	uint32_t v;

	v = bswap32(*((uint32_t *)src));

	return (intpcm_read_ieee754_32ne((uint8_t *)&v));
#else
	uint8_t b[sizeof(uint32_t)];

	*((uint32_t *)b) = bswap32(*((uint32_t *)src));

	return (intpcm_read_ieee754_32ne(b));
#endif
}

static __inline void
intpcm_write_ieee754_32oe(uint8_t *dst, intpcm_t v)
{

	intpcm_write_ieee754_32ne(dst, v);
	*((uint32_t *)dst) = bswap32(*((uint32_t *)dst));
}

#if BYTE_ORDER == LITTLE_ENDIAN
#define	intpcm_read_ieee754_32le	intpcm_read_ieee754_32ne
#define	intpcm_read_ieee754_32be	intpcm_read_ieee754_32oe
#define	intpcm_write_ieee754_32le	intpcm_write_ieee754_32ne
#define	intpcm_write_ieee754_32be	intpcm_write_ieee754_32oe
#else  /* !LITTLE_ENDIAN */
#define	intpcm_read_ieee754_32le	intpcm_read_ieee754_32oe
#define	intpcm_read_ieee754_32be	intpcm_read_ieee754_32ne
#define	intpcm_write_ieee754_32le	intpcm_write_ieee754_32oe
#define	intpcm_write_ieee754_32be	intpcm_write_ieee754_32ne
#endif /* LITTLE_ENDIAN */
#endif /* SND_IEEE754_OE */

int
main(int argc, char **argv)
{
	uint32_t v, w;
	uint8_t b[sizeof(uint32_t)];
	int32_t s;
	float f, g;
	int i, j;

	for (j = 1; j < argc ; j++) {
		printf("***** FLOAT: [ %s ]\n", argv[j]);
		if (strncmp(argv[j], "oe:", 3) == 0) {
			f = strtof(argv[j] + 3, NULL);
			memcpy(b, &f, sizeof(b));
			*((uint32_t *)b) = bswap32(*((uint32_t *)b));
			s = intpcm_read_ieee754_32oe(b);
			intpcm_write_ieee754_32oe(b, s);
			*((uint32_t *)b) = bswap32(*((uint32_t *)b));
			memcpy(&g, b, sizeof(g));
			printf("   -> %.16f\n   <- %.16f\n err: %.16f\n",
			    (double)f, (double)g, (double)f - g);
		} else
			f = strtof(argv[j], NULL);
		memcpy(b, &f, sizeof(b));
		v = *((uint32_t *)b);
		s = intpcm_read_float(b);
		intpcm_write_float(b, s);
		w = *((uint32_t *)b);
		memcpy(&g, b, sizeof(g));
		printf(" %.16f / 0x%08x -> %d\n 0x%08x / %.16f "
		    "(err: %.16f)\n\t%u "
		    "[ %u -> %d ] [ %u -> %u ]\n",
		    (double)f, v, s, w, (double)g,
		    (double)f - g,
		    v >> 31, (v >> 23) & 0xff,
		    ((int)(v >> 23) & 0xff) - 127,
		    v & ((1 << 23) - 1), (1 << 23) | (v & ((1 << 23) - 1)));

		printf("\t%u ", v >> 31);

		for (i = 30; i >= 23; i--)
			printf("%u", (v >> i) & 0x1);

		printf(" *");

		for (i = 23; i >= 0; i--)
			printf("%u", ((v | (1 << 23)) >> i) & 0x1);

		printf("\n");

	}
	return (0);
}