/*
 * Copyright (c) 2003, 2007-14 Matteo Frigo
 * Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
 *
 * 128-bit AVX2 support by Erik Lindahl, 2015.
 * Erik Lindahl hereby places his modifications in the public domain.
 * 
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#if defined(FFTW_LDOUBLE) || defined(FFTW_QUAD)
#error "AVX2 only works in single or double precision"
#endif

#ifdef FFTW_SINGLE
#  define DS(d,s) s /* single-precision option */
#  define SUFF(name) name ## s
#else
#  define DS(d,s) d /* double-precision option */
#  define SUFF(name) name ## d
#endif

#define SIMD_SUFFIX  _avx2_128  /* for renaming */
#define VL DS(1,2)         /* SIMD vector length, in term of complex numbers */
#define SIMD_VSTRIDE_OKA(x) DS(1,((x) == 2))
#define SIMD_STRIDE_OKPAIR SIMD_STRIDE_OK

#if defined(__GNUC__) && !defined(__AVX2__) /* sanity check */
#error "compiling simd-avx2-128.h without avx2 support"
#endif

#ifdef _MSC_VER
#ifndef inline
#define inline __inline
#endif
#endif

#include <immintrin.h>

typedef DS(__m128d,__m128) V;
#define VADD SUFF(_mm_add_p)
#define VSUB SUFF(_mm_sub_p)
#define VMUL SUFF(_mm_mul_p)
#define VXOR SUFF(_mm_xor_p)
#define SHUF SUFF(_mm_shuffle_p)
#define VPERM1 SUFF(_mm_permute_p)
#define UNPCKL SUFF(_mm_unpacklo_p)
#define UNPCKH SUFF(_mm_unpackhi_p)

#define SHUFVALS(fp0,fp1,fp2,fp3) \
   (((fp3) << 6) | ((fp2) << 4) | ((fp1) << 2) | ((fp0)))

#define VDUPL(x) DS(_mm_permute_pd(x,0), _mm_moveldup_ps(x))
#define VDUPH(x) DS(_mm_permute_pd(x,3), _mm_movehdup_ps(x))
#define LOADH(addr, val) _mm_loadh_pi(val, (const __m64 *)(addr))
#define LOADL(addr, val) _mm_loadl_pi(val, (const __m64 *)(addr))
#define STOREH(a, v) DS(_mm_storeh_pd(a, v), _mm_storeh_pi((__m64 *)(a), v))
#define STOREL(a, v) DS(_mm_storel_pd(a, v), _mm_storel_pi((__m64 *)(a), v))

#define VLIT(x0, x1) DS(_mm_set_pd(x0, x1), _mm_set_ps(x0, x1, x0, x1))
#define DVK(var, val) V var = VLIT(val, val)
#define LDK(x) x

static inline V LDA(const R *x, INT ivs, const R *aligned_like)
{
     (void)aligned_like; /* UNUSED */
     (void)ivs; /* UNUSED */
     return *(const V *)x;
}

static inline void STA(R *x, V v, INT ovs, const R *aligned_like)
{
     (void)aligned_like; /* UNUSED */
     (void)ovs; /* UNUSED */
     *(V *)x = v;
}

#ifdef FFTW_SINGLE

#  ifdef _MSC_VER
     /* Temporarily disable the warning "uninitialized local variable
	'name' used" and runtime checks for using a variable before it is
	defined which is erroneously triggered by the LOADL0 / LOADH macros
	as they only modify VAL partly each. */
#    ifndef __INTEL_COMPILER
#      pragma warning(disable : 4700)
#      pragma runtime_checks("u", off)
#    endif
#  endif
#  ifdef __INTEL_COMPILER
#    pragma warning(disable : 592)
#  endif

static inline V LD(const R *x, INT ivs, const R *aligned_like)
{
    __m128 l0, l1;
    (void)aligned_like; /* UNUSED */
#if defined(__ICC) || (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ > 8)
    l0 = LOADL(x, SUFF(_mm_undefined_p)());
    l1 = LOADL(x + ivs, SUFF(_mm_undefined_p)());
#else
    l0 = LOADL(x, l0);
    l1 = LOADL(x + ivs, l1);
#endif
    return SUFF(_mm_movelh_p)(l0,l1);
}

#  ifdef _MSC_VER
#    ifndef __INTEL_COMPILER
#      pragma warning(default : 4700)
#      pragma runtime_checks("u", restore)
#    endif
#  endif
#  ifdef __INTEL_COMPILER
#    pragma warning(default : 592)
#  endif

static inline void ST(R *x, V v, INT ovs, const R *aligned_like)
{
     (void)aligned_like; /* UNUSED */
     /* WARNING: the extra_iter hack depends upon STOREL occurring
	after STOREH */
     STOREH(x + ovs, v);
     STOREL(x, v);
}

#else /* ! FFTW_SINGLE */
#  define LD LDA
#  define ST STA
#endif

#define STM2 DS(STA,ST)
#define STN2(x, v0, v1, ovs) /* nop */

#ifdef FFTW_SINGLE
#  define STM4(x, v, ovs, aligned_like) /* no-op */
/* STN4 is a macro, not a function, thanks to Visual C++ developers
   deciding "it would be infrequent that people would want to pass more
   than 3 [__m128 parameters] by value."  3 parameters ought to be enough
   for anybody. */
#  define STN4(x, v0, v1, v2, v3, ovs)			\
{							\
     V xxx0, xxx1, xxx2, xxx3;				\
     xxx0 = UNPCKL(v0, v2);				\
     xxx1 = UNPCKH(v0, v2);				\
     xxx2 = UNPCKL(v1, v3);				\
     xxx3 = UNPCKH(v1, v3);				\
     STA(x, UNPCKL(xxx0, xxx2), 0, 0);			\
     STA(x + ovs, UNPCKH(xxx0, xxx2), 0, 0);		\
     STA(x + 2 * ovs, UNPCKL(xxx1, xxx3), 0, 0);	\
     STA(x + 3 * ovs, UNPCKH(xxx1, xxx3), 0, 0);	\
}
#else /* !FFTW_SINGLE */
static inline void STM4(R *x, V v, INT ovs, const R *aligned_like)
{
     (void)aligned_like; /* UNUSED */
     STOREL(x, v);
     STOREH(x + ovs, v);
}
#  define STN4(x, v0, v1, v2, v3, ovs) /* nothing */
#endif

static inline V FLIP_RI(V x)
{
     return VPERM1(x, DS(1, SHUFVALS(1, 0, 3, 2)));
}

static inline V VCONJ(V x)
{
     /* Produce a SIMD vector[VL] of (0 + -0i). 

        We really want to write this:

           V pmpm = VLIT(-0.0, 0.0);

        but historically some compilers have ignored the distiction
        between +0 and -0.  It looks like 'gcc-8 -fast-math' treats -0
        as 0 too.
      */
     union uvec {
          unsigned u[4];
          V v;
     };
     static const union uvec pmpm = {
#ifdef FFTW_SINGLE
          { 0x00000000, 0x80000000, 0x00000000, 0x80000000 }
#else
          { 0x00000000, 0x00000000, 0x00000000, 0x80000000 }
#endif
     };
     return VXOR(pmpm.v, x);
}

static inline V VBYI(V x)
{
     x = VCONJ(x);
     x = FLIP_RI(x);
     return x;
}

/* FMA support */
#define VFMA(a, b, c)  SUFF(_mm_fmadd_p)(a,b,c)
#define VFNMS(a, b, c) SUFF(_mm_fnmadd_p)(a,b,c)
#define VFMS(a, b, c)  SUFF(_mm_fmsub_p)(a,b,c)
#define VFMAI(b, c)    SUFF(_mm_addsub_p)(c,FLIP_RI(b))
#define VFNMSI(b, c)   VSUB(c, VBYI(b))
#define VFMACONJ(b,c)  VADD(VCONJ(b),c)
#define VFMSCONJ(b,c)  VSUB(VCONJ(b),c)
#define VFNMSCONJ(b,c) SUFF(_mm_addsub_p)(c,b)


static inline V VZMUL(V tx, V sr)
{
    V tr = VDUPL(tx);
    V ti = VDUPH(tx);
    ti = VMUL(ti, FLIP_RI(sr));
    return SUFF(_mm_fmaddsub_p)(tr,sr,ti);
}

static inline V VZMULJ(V tx, V sr)
{
     V tr = VDUPL(tx);
     V ti = VDUPH(tx);
     ti = VMUL(ti, FLIP_RI(sr));
     return SUFF(_mm_fmsubadd_p)(tr,sr,ti);
}

static inline V VZMULI(V tx, V sr)
{
     V tr = VDUPL(tx);
     V ti = VDUPH(tx);
     ti = VMUL(ti, sr);
     sr = VBYI(sr);
     return VFMS(tr, sr, ti);
}

static inline V VZMULIJ(V tx, V sr)
{
    V tr = VDUPL(tx);
    V ti = VDUPH(tx);
    tr = VMUL(tr, FLIP_RI(sr));
    return SUFF(_mm_fmaddsub_p)(ti,sr,tr);
}

/* twiddle storage #1: compact, slower */
#ifdef FFTW_SINGLE
#  define VTW1(v,x)  \
  {TW_COS, v, x}, {TW_COS, v+1, x}, {TW_SIN, v, x}, {TW_SIN, v+1, x}
static inline V BYTW1(const R *t, V sr)
{
    const V *twp = (const V *)t;
    V tx = twp[0];
    V tr = UNPCKL(tx, tx);
    V ti = UNPCKH(tx, tx);
    ti = VMUL(ti, FLIP_RI(sr));
    return SUFF(_mm_fmaddsub_p)(tr,sr,ti);
}
static inline V BYTWJ1(const R *t, V sr)
{
    const V *twp = (const V *)t;
    V tx = twp[0];
    V tr = UNPCKL(tx, tx);
    V ti = UNPCKH(tx, tx);
    ti = VMUL(ti, FLIP_RI(sr));
    return SUFF(_mm_fmsubadd_p)(tr,sr,ti);
}
#else /* !FFTW_SINGLE */
#  define VTW1(v,x) {TW_CEXP, v, x}
static inline V BYTW1(const R *t, V sr)
{
     V tx = LD(t, 1, t);
     return VZMUL(tx, sr);
}
static inline V BYTWJ1(const R *t, V sr)
{
     V tx = LD(t, 1, t);
     return VZMULJ(tx, sr);
}
#endif
#define TWVL1 (VL)

/* twiddle storage #2: twice the space, faster (when in cache) */
#ifdef FFTW_SINGLE
#  define VTW2(v,x)							\
  {TW_COS, v, x}, {TW_COS, v, x}, {TW_COS, v+1, x}, {TW_COS, v+1, x},	\
  {TW_SIN, v, -x}, {TW_SIN, v, x}, {TW_SIN, v+1, -x}, {TW_SIN, v+1, x}
#else /* !FFTW_SINGLE */
#  define VTW2(v,x)							\
  {TW_COS, v, x}, {TW_COS, v, x}, {TW_SIN, v, -x}, {TW_SIN, v, x}
#endif
#define TWVL2 (2 * VL)
static inline V BYTW2(const R *t, V sr)
{
     const V *twp = (const V *)t;
     V si = FLIP_RI(sr);
     V tr = twp[0], ti = twp[1];
     return VFMA(tr, sr, VMUL(ti, si));
}
static inline V BYTWJ2(const R *t, V sr)
{
     const V *twp = (const V *)t;
     V si = FLIP_RI(sr);
     V tr = twp[0], ti = twp[1];
     return VFNMS(ti, si, VMUL(tr, sr));
}

/* twiddle storage #3 */
#ifdef FFTW_SINGLE
#  define VTW3(v,x) {TW_CEXP, v, x}, {TW_CEXP, v+1, x}
#  define TWVL3 (VL)
#else
#  define VTW3(v,x) VTW1(v,x)
#  define TWVL3 TWVL1
#endif

/* twiddle storage for split arrays */
#ifdef FFTW_SINGLE
#  define VTWS(v,x)							  \
    {TW_COS, v, x}, {TW_COS, v+1, x}, {TW_COS, v+2, x}, {TW_COS, v+3, x}, \
    {TW_SIN, v, x}, {TW_SIN, v+1, x}, {TW_SIN, v+2, x}, {TW_SIN, v+3, x}
#else
#  define VTWS(v,x)							  \
    {TW_COS, v, x}, {TW_COS, v+1, x}, {TW_SIN, v, x}, {TW_SIN, v+1, x}
#endif
#define TWVLS (2 * VL)

#define VLEAVE() /* nothing */

#include "simd-common.h"