90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
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// Copyright 2016 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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package pmem
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import (
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"bytes"
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"math/rand"
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)
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// TestCopy is used by CPU drivers to verify that the DMA engine works
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// correctly.
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//
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// It is not meant to be used by end users.
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//
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// TestCopy allocates two buffer via `alloc`, once as the source and one as the
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// destination. It fills the source with random data and the destination with
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// 0x11.
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//
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// `copyMem` is expected to copy the memory from pSrc to pDst, with an offset
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// of `hole` and size `size-2*hole`.
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//
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// The function `copyMem` being tested is only given the buffer physical
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// addresses and must copy the data without other help. It is expected to
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//
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// This confirm misaligned DMA copying works.
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// leverage the host's DMA engine.
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func TestCopy(size, holeSize int, alloc func(size int) (Mem, error), copyMem func(pDst, pSrc uint64) error) error {
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pSrc, err2 := alloc(size)
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if err2 != nil {
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return err2
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}
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defer pSrc.Close()
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pDst, err2 := alloc(size)
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if err2 != nil {
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return err2
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}
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defer pDst.Close()
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dst := pDst.Bytes()
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for i := range dst {
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dst[i] = 0x11
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}
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src := make([]byte, size)
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for i := range src {
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src[i] = byte(rand.Int31())
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}
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copy(pSrc.Bytes(), src[:])
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// Run the driver supplied memory copying code.
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if err := copyMem(pDst.PhysAddr(), pSrc.PhysAddr()); err != nil {
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return err
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}
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// Verifications.
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for i := 0; i < holeSize; i++ {
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if dst[i] != 0x11 {
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return wrapf("DMA corrupted the buffer header: %x", dst[:holeSize])
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}
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if dst[size-1-i] != 0x11 {
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return wrapf("DMA corrupted the buffer footer: %x", dst[size-1-holeSize:])
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}
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}
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// Headers and footers were not corupted in the destination. Verify the inner
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// view that should match.
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x := src[:size-2*holeSize]
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y := dst[holeSize : size-holeSize]
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if !bytes.Equal(x, y) {
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offset := 0
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for len(x) != 0 && x[0] == y[0] {
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x = x[1:]
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y = y[1:]
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offset++
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}
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for len(x) != 0 && x[len(x)-1] == y[len(y)-1] {
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x = x[:len(x)-1]
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y = y[:len(y)-1]
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}
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if len(x) > 32 {
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x = x[:32]
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}
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if len(y) > 32 {
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y = y[:32]
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}
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return wrapf("DMA corrupted the buffer at offset %d:\n%x\n%x", offset, x, y)
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}
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return nil
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}
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