33 lines
1.0 KiB
Go
33 lines
1.0 KiB
Go
// Copyright ©2015 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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//go:build !safe
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// +build !safe
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package mat
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import "unsafe"
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// offset returns the number of float64 values b[0] is after a[0].
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func offset(a, b []float64) int {
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if &a[0] == &b[0] {
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return 0
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}
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// This expression must be atomic with respect to GC moves.
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// At this stage this is true, because the GC does not
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// move. See https://golang.org/issue/12445.
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return int(uintptr(unsafe.Pointer(&b[0]))-uintptr(unsafe.Pointer(&a[0]))) / int(unsafe.Sizeof(float64(0)))
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}
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// offsetComplex returns the number of complex128 values b[0] is after a[0].
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func offsetComplex(a, b []complex128) int {
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if &a[0] == &b[0] {
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return 0
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}
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// This expression must be atomic with respect to GC moves.
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// At this stage this is true, because the GC does not
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// move. See https://golang.org/issue/12445.
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return int(uintptr(unsafe.Pointer(&b[0]))-uintptr(unsafe.Pointer(&a[0]))) / int(unsafe.Sizeof(complex128(0)))
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}
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