1// Copyright ©2016 The Gonum Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4//
5// Some of the loop unrolling code is copied from:
6// http://golang.org/src/math/big/arith_amd64.s
7// which is distributed under these terms:
8//
9// Copyright (c) 2012 The Go Authors. All rights reserved.
10//
11// Redistribution and use in source and binary forms, with or without
12// modification, are permitted provided that the following conditions are
13// met:
14//
15//    * Redistributions of source code must retain the above copyright
16// notice, this list of conditions and the following disclaimer.
17//    * Redistributions in binary form must reproduce the above
18// copyright notice, this list of conditions and the following disclaimer
19// in the documentation and/or other materials provided with the
20// distribution.
21//    * Neither the name of Google Inc. nor the names of its
22// contributors may be used to endorse or promote products derived from
23// this software without specific prior written permission.
24//
25// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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35// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36
37// +build !noasm,!gccgo,!safe
38
39#include "textflag.h"
40
41#define MOVDDUP_ALPHA    LONG $0x44120FF2; WORD $0x2024 // @ MOVDDUP 32(SP), X0  /*XMM0, 32[RSP]*/
42
43#define X_PTR SI
44#define DST_PTR DI
45#define IDX AX
46#define LEN CX
47#define TAIL BX
48#define ALPHA X0
49#define ALPHA_2 X1
50
51// func ScalUnitaryTo(dst []float64, alpha float64, x []float64)
52// This function assumes len(dst) >= len(x).
53TEXT ·ScalUnitaryTo(SB), NOSPLIT, $0
54	MOVQ x_base+32(FP), X_PTR    // X_PTR = &x
55	MOVQ dst_base+0(FP), DST_PTR // DST_PTR = &dst
56	MOVDDUP_ALPHA                // ALPHA = { alpha, alpha }
57	MOVQ x_len+40(FP), LEN       // LEN = len(x)
58	CMPQ LEN, $0
59	JE   end                     // if LEN == 0 { return }
60
61	XORQ IDX, IDX   // IDX = 0
62	MOVQ LEN, TAIL
63	ANDQ $7, TAIL   // TAIL = LEN % 8
64	SHRQ $3, LEN    // LEN = floor( LEN / 8 )
65	JZ   tail_start // if LEN == 0 { goto tail_start }
66
67	MOVUPS ALPHA, ALPHA_2 // ALPHA_2 = ALPHA for pipelining
68
69loop:  // do { // dst[i] = alpha * x[i] unrolled 8x.
70	MOVUPS (X_PTR)(IDX*8), X2   // X_i = x[i]
71	MOVUPS 16(X_PTR)(IDX*8), X3
72	MOVUPS 32(X_PTR)(IDX*8), X4
73	MOVUPS 48(X_PTR)(IDX*8), X5
74
75	MULPD ALPHA, X2   // X_i *= ALPHA
76	MULPD ALPHA_2, X3
77	MULPD ALPHA, X4
78	MULPD ALPHA_2, X5
79
80	MOVUPS X2, (DST_PTR)(IDX*8)   // dst[i] = X_i
81	MOVUPS X3, 16(DST_PTR)(IDX*8)
82	MOVUPS X4, 32(DST_PTR)(IDX*8)
83	MOVUPS X5, 48(DST_PTR)(IDX*8)
84
85	ADDQ $8, IDX  // i += 8
86	DECQ LEN
87	JNZ  loop     // while --LEN > 0
88	CMPQ TAIL, $0
89	JE   end      // if TAIL == 0 { return }
90
91tail_start: // Reset loop counters
92	MOVQ TAIL, LEN // Loop counter: LEN = TAIL
93	SHRQ $1, LEN   // LEN = floor( TAIL / 2 )
94	JZ   tail_one  // if LEN == 0 { goto tail_one }
95
96tail_two: // do {
97	MOVUPS (X_PTR)(IDX*8), X2   // X_i = x[i]
98	MULPD  ALPHA, X2            // X_i *= ALPHA
99	MOVUPS X2, (DST_PTR)(IDX*8) // dst[i] = X_i
100	ADDQ   $2, IDX              // i += 2
101	DECQ   LEN
102	JNZ    tail_two             // while --LEN > 0
103
104	ANDQ $1, TAIL
105	JZ   end      // if TAIL == 0 { return }
106
107tail_one:
108	MOVSD (X_PTR)(IDX*8), X2   // X_i = x[i]
109	MULSD ALPHA, X2            // X_i *= ALPHA
110	MOVSD X2, (DST_PTR)(IDX*8) // dst[i] = X_i
111
112end:
113	RET
114