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,
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31 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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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
52 // func ScalIncTo(dst []float64, incDst uintptr, alpha float64, x []float64, n, incX uintptr)
53 TEXT ·ScalIncTo(SB), NOSPLIT, $0
54 MOVQ dst_base+0(FP), DST_PTR // DST_PTR = &dst
55 MOVQ incDst+24(FP), INC_DST // INC_DST = incDst
56 SHLQ $3, INC_DST // INC_DST *= sizeof(float64)
57 MOVSD alpha+32(FP), ALPHA // ALPHA = alpha
58 MOVQ x_base+40(FP), X_PTR // X_PTR = &x
59 MOVQ n+64(FP), LEN // LEN = n
60 MOVQ incX+72(FP), INC_X // INC_X = incX
61 SHLQ $3, INC_X // INC_X *= sizeof(float64)
63 JE end // if LEN == 0 { return }
66 ANDQ $3, TAIL // TAIL = LEN % 4
67 SHRQ $2, LEN // LEN = floor( LEN / 4 )
68 JZ tail_start // if LEN == 0 { goto tail_start }
70 MOVUPS ALPHA, ALPHA_2 // ALPHA_2 = ALPHA for pipelining
71 LEAQ (INC_X)(INC_X*2), INCx3_X // INCx3_X = INC_X * 3
72 LEAQ (INC_DST)(INC_DST*2), INCx3_DST // INCx3_DST = INC_DST * 3
74 loop: // do { // x[i] *= alpha unrolled 4x.
75 MOVSD (X_PTR), X2 // X_i = x[i]
76 MOVSD (X_PTR)(INC_X*1), X3
77 MOVSD (X_PTR)(INC_X*2), X4
78 MOVSD (X_PTR)(INCx3_X*1), X5
80 MULSD ALPHA, X2 // X_i *= a
85 MOVSD X2, (DST_PTR) // dst[i] = X_i
86 MOVSD X3, (DST_PTR)(INC_DST*1)
87 MOVSD X4, (DST_PTR)(INC_DST*2)
88 MOVSD X5, (DST_PTR)(INCx3_DST*1)
90 LEAQ (X_PTR)(INC_X*4), X_PTR // X_PTR = &(X_PTR[incX*4])
91 LEAQ (DST_PTR)(INC_DST*4), DST_PTR // DST_PTR = &(DST_PTR[incDst*4])
93 JNZ loop // } while --LEN > 0
95 JE end // if TAIL == 0 { return }
97 tail_start: // Reset loop registers
98 MOVQ TAIL, LEN // Loop counter: LEN = TAIL
99 SHRQ $1, LEN // LEN = floor( LEN / 2 )
103 MOVSD (X_PTR), X2 // X_i = x[i]
104 MOVSD (X_PTR)(INC_X*1), X3
105 MULSD ALPHA, X2 // X_i *= a
107 MOVSD X2, (DST_PTR) // dst[i] = X_i
108 MOVSD X3, (DST_PTR)(INC_DST*1)
110 LEAQ (X_PTR)(INC_X*2), X_PTR // X_PTR = &(X_PTR[incX*2])
111 LEAQ (DST_PTR)(INC_DST*2), DST_PTR // DST_PTR = &(DST_PTR[incDst*2])
117 MOVSD (X_PTR), X2 // X_i = x[i]
118 MULSD ALPHA, X2 // X_i *= ALPHA
119 MOVSD X2, (DST_PTR) // x[i] = X_i