forked from LaconicNetwork/kompose
81 lines
2.0 KiB
Go
81 lines
2.0 KiB
Go
// Copyright ©2014 The gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package mat64
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import (
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"sync"
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"github.com/gonum/blas/blas64"
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)
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var tab64 = [64]byte{
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0x3f, 0x00, 0x3a, 0x01, 0x3b, 0x2f, 0x35, 0x02,
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0x3c, 0x27, 0x30, 0x1b, 0x36, 0x21, 0x2a, 0x03,
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0x3d, 0x33, 0x25, 0x28, 0x31, 0x12, 0x1c, 0x14,
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0x37, 0x1e, 0x22, 0x0b, 0x2b, 0x0e, 0x16, 0x04,
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0x3e, 0x39, 0x2e, 0x34, 0x26, 0x1a, 0x20, 0x29,
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0x32, 0x24, 0x11, 0x13, 0x1d, 0x0a, 0x0d, 0x15,
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0x38, 0x2d, 0x19, 0x1f, 0x23, 0x10, 0x09, 0x0c,
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0x2c, 0x18, 0x0f, 0x08, 0x17, 0x07, 0x06, 0x05,
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}
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// bits returns the ceiling of base 2 log of v.
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// Approach based on http://stackoverflow.com/a/11398748.
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func bits(v uint64) byte {
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if v == 0 {
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return 0
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}
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v <<= 2
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v--
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v |= v >> 1
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v |= v >> 2
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v |= v >> 4
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v |= v >> 8
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v |= v >> 16
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v |= v >> 32
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return tab64[((v-(v>>1))*0x07EDD5E59A4E28C2)>>58] - 1
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}
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// pool contains size stratified workspace Dense pools.
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// Each pool element i returns sized matrices with a data
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// slice capped at 1<<i.
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var pool [63]sync.Pool
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func init() {
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for i := range pool {
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l := 1 << uint(i)
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pool[i].New = func() interface{} {
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return &Dense{mat: blas64.General{
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Data: make([]float64, l),
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}}
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}
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}
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}
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// getWorkspace returns a *Dense of size r×c and a data slice
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// with a cap that is less than 2*r*c. If clear is true, the
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// data slice visible through the Matrix interface is zeroed.
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func getWorkspace(r, c int, clear bool) *Dense {
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l := uint64(r * c)
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w := pool[bits(l)].Get().(*Dense)
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w.mat.Data = w.mat.Data[:l]
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if clear {
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zero(w.mat.Data)
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}
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w.mat.Rows = r
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w.mat.Cols = c
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w.mat.Stride = c
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w.capRows = r
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w.capCols = c
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return w
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}
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// putWorkspace replaces a used *Dense into the appropriate size
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// workspace pool. putWorkspace must not be called with a matrix
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// where references to the underlying data slice has been kept.
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func putWorkspace(w *Dense) {
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pool[bits(uint64(cap(w.mat.Data)))].Put(w)
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}
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