/*
 * libmad - MPEG audio decoder library
 * Copyright (C) 2000-2004 Underbit Technologies, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id: fixed.h,v 1.38 2004/02/17 02:02:03 rob Exp $
 */

#pragma once
#include "common/standard_types.h"


using mad_fixed_t	  = int32;
using mad_fixed64hi_t = int32;
using mad_fixed64lo_t = uint32;
using mad_fixed64_t	  = int64;
using mad_sample_t	  = mad_fixed_t;

/*
 * Fixed-point format: 0xABBBBBBB
 * A == whole part      (sign + 3 bits)
 * B == fractional part (28 bits)
 *
 * Values are signed two's complement, so the effective range is:
 * 0x80000000 to 0x7fffffff
 *       -8.0 to +7.9999999962747097015380859375
 *
 * The smallest representable value is:
 * 0x00000001 == 0.0000000037252902984619140625 (i.e. about 3.725e-9)
 *
 * 28 bits of fractional accuracy represent about
 * 8.6 digits of decimal accuracy.
 *
 * Fixed-point numbers can be added or subtracted as normal
 * integers, but multiplication requires shifting the 64-bit result
 * from 56 fractional bits back to 28 (and rounding.)
 */

#define MAD_F_FRACBITS 28
#define MAD_F(x)	   mad_fixed_t(x##L)
#define MAD_F_MIN	   MAD_F(-0x80000000)
#define MAD_F_MAX	   MAD_F(+0x7fffffff)
#define MAD_F_ONE	   MAD_F(+0x10000000)

#define mad_f_intpart(x)  ((x) >> MAD_F_FRACBITS)
#define mad_f_fracpart(x) ((x) & ((1L << MAD_F_FRACBITS) - 1))
/* (x should be positive) */

#define mad_f_add(x, y) ((x) + (y))
#define mad_f_sub(x, y) ((x) - (y))

#if defined(FPM_INTEL) || defined(FPM_ARM) || defined(FPM_MIPS) || defined(FPM_SPARC) || defined(FPM_PPC)
  #error "assembler versions were removed. original source with asm support: https://github.com/markjeee/libmad"
#endif

#if defined(FPM_64BIT)

// This version should be the most accurate if 64-bit types are supported by
// the compiler, although it may not be the most efficient.

  #if defined(OPT_ACCURACY)
	#define mad_f_mul(x, y) \
		((mad_fixed_t)((((mad_fixed64_t)(x) * (y)) + (1L << (MAD_F_SCALEBITS - 1))) >> MAD_F_SCALEBITS))
  #else
	#define mad_f_mul(x, y) ((mad_fixed_t)(((mad_fixed64_t)(x) * (y)) >> MAD_F_SCALEBITS))
  #endif

  #define MAD_F_SCALEBITS MAD_F_FRACBITS

#elif defined(FPM_DEFAULT)

// This version is the most portable but it loses significant accuracy.
// Furthermore, accuracy is biased against the second argument, so care
// should be taken when ordering operands.
//
// The scale factors are constant as this is not used with SSO.
//
// Pre-rounding is required to stay within the limits of compliance.

  #if defined(OPT_SPEED)
	#define mad_f_mul(x, y) (((x) >> 12) * ((y) >> 16))
  #else
	#define mad_f_mul(x, y) ((((x) + (1L << 11)) >> 12) * (((y) + (1L << 15)) >> 16))
  #endif

#else
  #error "no FPM selected"
#endif

/* default implementations */

#if !defined(mad_f_mul)
  #define mad_f_mul(x, y)                \
	  ({                                 \
		mad_fixed64hi_t __hi;            \
		mad_fixed64lo_t __lo;            \
		MAD_F_MLX(__hi, __lo, (x), (y)); \
		mad_f_scale64(__hi, __lo);       \
	  })
#endif

#if !defined(MAD_F_MLA)
  #define MAD_F_ML0(hi, lo, x, y) ((lo) = mad_f_mul((x), (y)))
  #define MAD_F_MLA(hi, lo, x, y) ((lo) += mad_f_mul((x), (y)))
  #define MAD_F_MLN(hi, lo)		  ((lo) = -(lo))
  #define MAD_F_MLZ(hi, lo)		  ((void)(hi), (mad_fixed_t)(lo))
#endif

#if !defined(MAD_F_ML0)
  #define MAD_F_ML0(hi, lo, x, y) MAD_F_MLX((hi), (lo), (x), (y))
#endif

#if !defined(MAD_F_MLN)
  #define MAD_F_MLN(hi, lo) ((hi) = ((lo) = -(lo)) ? ~(hi) : -(hi))
#endif

#if !defined(MAD_F_MLZ)
  #define MAD_F_MLZ(hi, lo) mad_f_scale64((hi), (lo))
#endif

#if !defined(mad_f_scale64)
  #if defined(OPT_ACCURACY)
	#define mad_f_scale64(hi, lo) \
		(((mad_fixed_t(((hi) << (32 - (MAD_F_SCALEBITS - 1))) | ((lo) >> (MAD_F_SCALEBITS - 1)))) + 1) >> 1)
  #else
	#define mad_f_scale64(hi, lo) (mad_fixed_t(((hi) << (32 - MAD_F_SCALEBITS)) | ((lo) >> MAD_F_SCALEBITS)))
  #endif
  #define MAD_F_SCALEBITS MAD_F_FRACBITS
#endif