comparison src/fftw-3.3.3/simd-support/simd-neon.h @ 10:37bf6b4a2645

Add FFTW3

+/*
+ * Copyright (c) 2003, 2007-11 Matteo Frigo
+ * Copyright (c) 2003, 2007-11 Massachusetts Institute of Technology
+ *
+ * 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
+ *
+ */
+
+#ifndef FFTW_SINGLE
+#error "NEON only works in single precision"
+#endif
+
+/* define these unconditionally, because they are used by
+   taint.c which is compiled without neon */
+#define SIMD_SUFFIX _neon	/* for renaming */
+#define VL 2            /* SIMD complex vector length */
+#define SIMD_VSTRIDE_OKA(x) ((x) == 2)
+#define SIMD_STRIDE_OKPAIR SIMD_STRIDE_OK
+
+#if defined(__GNUC__) && !defined(__ARM_NEON__)
+#error "compiling simd-neon.h requires -mfpu=neon or equivalent"
+#endif
+
+#include <arm_neon.h>
+
+/* FIXME: I am not sure whether this code assumes little-endian
+   ordering.  VLIT may or may not be wrong for big-endian systems. */
+typedef float32x4_t V;
+
+#define VLIT(x0, x1, x2, x3) {x0, x1, x2, x3}
+#define LDK(x) x
+#define DVK(var, val) const V var = VLIT(val, val, val, val)
+
+/* NEON has FMA, but a three-operand FMA is not too useful
+   for FFT purposes.  We normally compute
+
+      t0=a+b*c
+      t1=a-b*c
+
+   In a three-operand instruction set this translates into
+
+      t0=a
+      t0+=b*c
+      t1=a
+      t1-=b*c
+
+   At least one move must be implemented, negating the advantage of
+   the FMA in the first place.  At least some versions of gcc generate
+   both moves.  So we are better off generating t=b*c;t0=a+t;t1=a-t;*/
+#if HAVE_FMA
+#warning "--enable-fma on NEON is probably a bad idea (see source code)"
+#endif
+
+#define VADD(a, b) vaddq_f32(a, b)
+#define VSUB(a, b) vsubq_f32(a, b)
+#define VMUL(a, b) vmulq_f32(a, b)
+#define VFMA(a, b, c) vmlaq_f32(c, a, b)	        /* a*b+c */
+#define VFNMS(a, b, c) vmlsq_f32(c, a, b)	/* FNMS=-(a*b-c) in powerpc terminology; MLS=c-a*b
+						   in ARM terminology */
+#define VFMS(a, b, c) VSUB(VMUL(a, b), c)	/* FMS=a*b-c in powerpc terminology; no equivalent
+						   arm instruction (?) */
+
+static inline V LDA(const R *x, INT ivs, const R *aligned_like)
+{
+     (void) aligned_like;	/* UNUSED */
+     return vld1q_f32((const float32_t *)x);
+}
+
+static inline V LD(const R *x, INT ivs, const R *aligned_like)
+{
+     (void) aligned_like;	/* UNUSED */
+     return vcombine_f32(vld1_f32((float32_t *)x), vld1_f32((float32_t *)(x + ivs)));
+}
+
+static inline void STA(R *x, V v, INT ovs, const R *aligned_like)
+{
+     (void) aligned_like;	/* UNUSED */
+     vst1q_f32((float32_t *)x, v);
+}
+
+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 store-low occurring
+	after store-high */
+     vst1_f32((float32_t *)(x + ovs), vget_high_f32(v));
+     vst1_f32((float32_t *)x, vget_low_f32(v));
+}
+
+/* 2x2 complex transpose and store */
+#define STM2 ST
+#define STN2(x, v0, v1, ovs) /* nop */
+
+/* store and 4x4 real transpose */
+static inline void STM4(R *x, V v, INT ovs, const R *aligned_like)
+{
+     (void) aligned_like;	/* UNUSED */
+     vst1_lane_f32((float32_t *)(x)      , vget_low_f32(v), 0);
+     vst1_lane_f32((float32_t *)(x + ovs), vget_low_f32(v), 1);
+     vst1_lane_f32((float32_t *)(x + 2 * ovs), vget_high_f32(v), 0);
+     vst1_lane_f32((float32_t *)(x + 3 * ovs), vget_high_f32(v), 1);
+}
+#define STN4(x, v0, v1, v2, v3, ovs)	/* use STM4 */
+
+#define FLIP_RI(x) vrev64q_f32(x)
+
+static inline V VCONJ(V x)
+{
+#if 1
+     static const uint32x4_t pm = {0, 0x80000000u, 0, 0x80000000u};
+     return vreinterpretq_f32_u32(veorq_u32(vreinterpretq_u32_f32(x), pm));
+#else
+     const V pm = VLIT(1.0, -1.0, 1.0, -1.0);
+     return VMUL(x, pm);
+#endif
+}
+
+static inline V VBYI(V x)
+{
+     return FLIP_RI(VCONJ(x));
+}
+
+static inline V VFMAI(V b, V c)
+{
+     const V mp = VLIT(-1.0, 1.0, -1.0, 1.0);
+     return VFMA(FLIP_RI(b), mp, c);
+}
+
+static inline V VFNMSI(V b, V c)
+{
+     const V mp = VLIT(-1.0, 1.0, -1.0, 1.0);
+     return VFNMS(FLIP_RI(b), mp, c);
+}
+
+static inline V VFMACONJ(V b, V c)
+{
+     const V pm = VLIT(1.0, -1.0, 1.0, -1.0);
+     return VFMA(b, pm, c);
+}
+
+static inline V VFNMSCONJ(V b, V c)
+{
+     const V pm = VLIT(1.0, -1.0, 1.0, -1.0);
+     return VFNMS(b, pm, c);
+}
+
+static inline V VFMSCONJ(V b, V c)
+{
+     return VSUB(VCONJ(b), c);
+}
+
+#if 1
+#define VEXTRACT_REIM(tr, ti, tx)                               \
+{                                                               \
+     tr = vcombine_f32(vdup_lane_f32(vget_low_f32(tx), 0),      \
+                       vdup_lane_f32(vget_high_f32(tx), 0));    \
+     ti = vcombine_f32(vdup_lane_f32(vget_low_f32(tx), 1),      \
+                       vdup_lane_f32(vget_high_f32(tx), 1));    \
+}
+#else
+/* this alternative might be faster in an ideal world, but gcc likes
+   to spill VVV onto the stack */
+#define VEXTRACT_REIM(tr, ti, tx)               \
+{                                               \
+     float32x4x2_t vvv = vtrnq_f32(tx, tx);     \
+     tr = vvv.val[0];                           \
+     ti = vvv.val[1];                           \
+}
+#endif
+
+static inline V VZMUL(V tx, V sr)
+{
+     V tr, ti;
+     VEXTRACT_REIM(tr, ti, tx);
+     tr = VMUL(sr, tr);
+     sr = VBYI(sr);
+     return VFMA(ti, sr, tr);
+}
+
+static inline V VZMULJ(V tx, V sr)
+{
+     V tr, ti;
+     VEXTRACT_REIM(tr, ti, tx);
+     tr = VMUL(sr, tr);
+     sr = VBYI(sr);
+     return VFNMS(ti, sr, tr);
+}
+
+static inline V VZMULI(V tx, V sr)
+{
+     V tr, ti;
+     VEXTRACT_REIM(tr, ti, tx);
+     ti = VMUL(ti, sr);
+     sr = VBYI(sr);
+     return VFMS(tr, sr, ti);
+}
+
+static inline V VZMULIJ(V tx, V sr)
+{
+     V tr, ti;
+     VEXTRACT_REIM(tr, ti, tx);
+     ti = VMUL(ti, sr);
+     sr = VBYI(sr);
+     return VFMA(tr, sr, ti);
+}
+
+/* twiddle storage #1: compact, slower */
+#define VTW1(v,x) {TW_CEXP, v, x}, {TW_CEXP, v+1, x}
+#define TWVL1 VL
+static inline V BYTW1(const R *t, V sr)
+{
+     V tx = LDA(t, 2, 0);
+     return VZMUL(tx, sr);
+}
+
+static inline V BYTWJ1(const R *t, V sr)
+{
+     V tx = LDA(t, 2, 0);
+     return VZMULJ(tx, sr);
+}
+
+/* twiddle storage #2: twice the space, faster (when in cache) */
+#  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}
+#define TWVL2 (2 * VL)
+
+static inline V BYTW2(const R *t, V sr)
+{
+     V si = FLIP_RI(sr);
+     V tr = LDA(t, 2, 0), ti = LDA(t+2*VL, 2, 0);
+     return VFMA(ti, si, VMUL(tr, sr));
+}
+
+static inline V BYTWJ2(const R *t, V sr)
+{
+     V si = FLIP_RI(sr);
+     V tr = LDA(t, 2, 0), ti = LDA(t+2*VL, 2, 0);
+     return VFNMS(ti, si, VMUL(tr, sr));
+}
+
+/* twiddle storage #3 */
+#  define VTW3(v,x) {TW_CEXP, v, x}, {TW_CEXP, v+1, x}
+#  define TWVL3 (VL)
+
+/* twiddle storage for split arrays */
+#  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}
+#define TWVLS (2 * VL)
+
+#define VLEAVE()		/* nothing */
+
+#include "simd-common.h"