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.
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:
9 // Copyright (c) 2012 The Go Authors. All rights reserved.
11 // Redistribution and use in source and binary forms, with or without
12 // modification, are permitted provided that the following conditions are
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
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.
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,
30 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 //+build !noasm,!appengine
49 // func ScalInc(alpha float64, x []float64, n, incX uintptr)
50 TEXT ·ScalInc(SB), NOSPLIT, $0
51 MOVSD alpha+0(FP), ALPHA // ALPHA = alpha
52 MOVQ x_base+8(FP), X_PTR // X_PTR = &x
53 MOVQ incX+40(FP), INC_X // INC_X = incX
54 SHLQ $3, INC_X // INC_X *= sizeof(float64)
55 MOVQ n+32(FP), LEN // LEN = n
57 JE end // if LEN == 0 { return }
60 ANDQ $3, TAIL // TAIL = LEN % 4
61 SHRQ $2, LEN // LEN = floor( LEN / 4 )
62 JZ tail_start // if LEN == 0 { goto tail_start }
64 MOVUPS ALPHA, ALPHA_2 // ALPHA_2 = ALPHA for pipelining
65 LEAQ (INC_X)(INC_X*2), INCx3_X // INCx3_X = INC_X * 3
67 loop: // do { // x[i] *= alpha unrolled 4x.
68 MOVSD (X_PTR), X2 // X_i = x[i]
69 MOVSD (X_PTR)(INC_X*1), X3
70 MOVSD (X_PTR)(INC_X*2), X4
71 MOVSD (X_PTR)(INCx3_X*1), X5
73 MULSD ALPHA, X2 // X_i *= a
78 MOVSD X2, (X_PTR) // x[i] = X_i
79 MOVSD X3, (X_PTR)(INC_X*1)
80 MOVSD X4, (X_PTR)(INC_X*2)
81 MOVSD X5, (X_PTR)(INCx3_X*1)
83 LEAQ (X_PTR)(INC_X*4), X_PTR // X_PTR = &(X_PTR[incX*4])
85 JNZ loop // } while --LEN > 0
87 JE end // if TAIL == 0 { return }
89 tail_start: // Reset loop registers
90 MOVQ TAIL, LEN // Loop counter: LEN = TAIL
91 SHRQ $1, LEN // LEN = floor( LEN / 2 )
95 MOVSD (X_PTR), X2 // X_i = x[i]
96 MOVSD (X_PTR)(INC_X*1), X3
97 MULSD ALPHA, X2 // X_i *= a
99 MOVSD X2, (X_PTR) // x[i] = X_i
100 MOVSD X3, (X_PTR)(INC_X*1)
102 LEAQ (X_PTR)(INC_X*2), X_PTR // X_PTR = &(X_PTR[incX*2])
108 MOVSD (X_PTR), X2 // X_i = x[i]
109 MULSD ALPHA, X2 // X_i *= ALPHA
110 MOVSD X2, (X_PTR) // x[i] = X_i