forked from openshift/origin
/
pool.go
80 lines (71 loc) · 1.97 KB
/
pool.go
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// Copyright ©2014 The gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mat64
import (
"sync"
"github.com/gonum/blas/blas64"
)
var tab64 = [64]byte{
0x3f, 0x00, 0x3a, 0x01, 0x3b, 0x2f, 0x35, 0x02,
0x3c, 0x27, 0x30, 0x1b, 0x36, 0x21, 0x2a, 0x03,
0x3d, 0x33, 0x25, 0x28, 0x31, 0x12, 0x1c, 0x14,
0x37, 0x1e, 0x22, 0x0b, 0x2b, 0x0e, 0x16, 0x04,
0x3e, 0x39, 0x2e, 0x34, 0x26, 0x1a, 0x20, 0x29,
0x32, 0x24, 0x11, 0x13, 0x1d, 0x0a, 0x0d, 0x15,
0x38, 0x2d, 0x19, 0x1f, 0x23, 0x10, 0x09, 0x0c,
0x2c, 0x18, 0x0f, 0x08, 0x17, 0x07, 0x06, 0x05,
}
// bits returns the ceiling of base 2 log of v.
// Approach based on http://stackoverflow.com/a/11398748.
func bits(v uint64) byte {
if v == 0 {
return 0
}
v <<= 2
v--
v |= v >> 1
v |= v >> 2
v |= v >> 4
v |= v >> 8
v |= v >> 16
v |= v >> 32
return tab64[((v-(v>>1))*0x07EDD5E59A4E28C2)>>58] - 1
}
// pool contains size stratified workspace Dense pools.
// Each pool element i returns sized matrices with a data
// slice capped at 1<<i.
var pool [63]sync.Pool
func init() {
for i := range pool {
l := 1 << uint(i)
pool[i].New = func() interface{} {
return &Dense{mat: blas64.General{
Data: make([]float64, l),
}}
}
}
}
// getWorkspace returns a *Dense of size r×c and a data slice
// with a cap that is less than 2*r*c. If clear is true, the
// data slice visible through the Matrix interface is zeroed.
func getWorkspace(r, c int, clear bool) *Dense {
l := uint64(r * c)
w := pool[bits(l)].Get().(*Dense)
w.mat.Data = w.mat.Data[:l]
if clear {
zero(w.mat.Data)
}
w.mat.Rows = r
w.mat.Cols = c
w.mat.Stride = c
w.capRows = r
w.capCols = c
return w
}
// putWorkspace replaces a used *Dense into the appropriate size
// workspace pool. putWorkspace must not be called with a matrix
// where references to the underlying data slice has been kept.
func putWorkspace(w *Dense) {
pool[bits(uint64(cap(w.mat.Data)))].Put(w)
}