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https://github.com/golang/go
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97 lines
1.9 KiB
C
97 lines
1.9 KiB
C
// Copyright 2009 The Go 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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// Heap map, 32-bit version
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// See malloc.h and mheap.c for overview.
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#include "runtime.h"
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#include "malloc.h"
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// 3-level radix tree mapping page ids to Span*.
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void
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MHeapMap_Init(MHeapMap *m, void *(*allocator)(size_t))
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{
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m->allocator = allocator;
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}
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MSpan*
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MHeapMap_Get(MHeapMap *m, PageID k)
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{
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int32 i1, i2;
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i2 = k & MHeapMap_Level2Mask;
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k >>= MHeapMap_Level2Bits;
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i1 = k & MHeapMap_Level1Mask;
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k >>= MHeapMap_Level1Bits;
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if(k != 0)
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throw("MHeapMap_Get");
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return m->p[i1]->s[i2];
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}
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MSpan*
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MHeapMap_GetMaybe(MHeapMap *m, PageID k)
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{
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int32 i1, i2;
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MHeapMapNode2 *p2;
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i2 = k & MHeapMap_Level2Mask;
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k >>= MHeapMap_Level2Bits;
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i1 = k & MHeapMap_Level1Mask;
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k >>= MHeapMap_Level1Bits;
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if(k != 0)
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throw("MHeapMap_Get");
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p2 = m->p[i1];
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if(p2 == nil)
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return nil;
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return p2->s[i2];
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}
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void
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MHeapMap_Set(MHeapMap *m, PageID k, MSpan *s)
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{
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int32 i1, i2;
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i2 = k & MHeapMap_Level2Mask;
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k >>= MHeapMap_Level2Bits;
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i1 = k & MHeapMap_Level1Mask;
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k >>= MHeapMap_Level1Bits;
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if(k != 0)
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throw("MHeapMap_Set");
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m->p[i1]->s[i2] = s;
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}
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// Allocate the storage required for entries [k, k+1, ..., k+len-1]
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// so that Get and Set calls need not check for nil pointers.
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bool
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MHeapMap_Preallocate(MHeapMap *m, PageID k, uintptr len)
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{
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uintptr end;
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int32 i1;
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MHeapMapNode2 *p2;
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end = k+len;
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while(k < end) {
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if((k >> MHeapMap_TotalBits) != 0)
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return false;
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i1 = (k >> MHeapMap_Level2Bits) & MHeapMap_Level1Mask;
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// first-level pointer
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if(m->p[i1] == nil) {
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p2 = m->allocator(sizeof *p2);
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if(p2 == nil)
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return false;
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sys_memclr((byte*)p2, sizeof *p2);
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m->p[i1] = p2;
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}
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// advance key past this leaf node
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k = ((k >> MHeapMap_Level2Bits) + 1) << MHeapMap_Level2Bits;
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}
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return true;
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}
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