mirror of https://gitee.com/openkylin/linux.git
151 lines
3.5 KiB
C
151 lines
3.5 KiB
C
/*
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* Implement primitive realloc(3) functionality.
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*
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* Author: Mark A. Greer <mgreer@mvista.com>
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*
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* 2006 (c) MontaVista, Software, Inc. This file is licensed under
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* the terms of the GNU General Public License version 2. This program
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* is licensed "as is" without any warranty of any kind, whether express
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* or implied.
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*/
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#include <stddef.h>
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#include "types.h"
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#include "page.h"
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#include "string.h"
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#include "ops.h"
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#define ENTRY_BEEN_USED 0x01
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#define ENTRY_IN_USE 0x02
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static struct alloc_info {
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unsigned long flags;
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unsigned long base;
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unsigned long size;
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} *alloc_tbl;
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static unsigned long tbl_entries;
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static unsigned long alloc_min;
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static unsigned long next_base;
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static unsigned long space_left;
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/*
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* First time an entry is used, its base and size are set.
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* An entry can be freed and re-malloc'd but its base & size don't change.
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* Should be smart enough for needs of bootwrapper.
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*/
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static void *simple_malloc(unsigned long size)
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{
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unsigned long i;
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struct alloc_info *p = alloc_tbl;
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if (size == 0)
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goto err_out;
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size = _ALIGN_UP(size, alloc_min);
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for (i=0; i<tbl_entries; i++, p++)
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if (!(p->flags & ENTRY_BEEN_USED)) { /* never been used */
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if (size <= space_left) {
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p->base = next_base;
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p->size = size;
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p->flags = ENTRY_BEEN_USED | ENTRY_IN_USE;
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next_base += size;
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space_left -= size;
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return (void *)p->base;
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}
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goto err_out; /* not enough space left */
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}
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/* reuse an entry keeping same base & size */
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else if (!(p->flags & ENTRY_IN_USE) && (size <= p->size)) {
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p->flags |= ENTRY_IN_USE;
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return (void *)p->base;
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}
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err_out:
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return NULL;
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}
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static struct alloc_info *simple_find_entry(void *ptr)
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{
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unsigned long i;
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struct alloc_info *p = alloc_tbl;
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for (i=0; i<tbl_entries; i++,p++) {
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if (!(p->flags & ENTRY_BEEN_USED))
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break;
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if ((p->flags & ENTRY_IN_USE) &&
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(p->base == (unsigned long)ptr))
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return p;
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}
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return NULL;
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}
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static void simple_free(void *ptr)
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{
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struct alloc_info *p = simple_find_entry(ptr);
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if (p != NULL)
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p->flags &= ~ENTRY_IN_USE;
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}
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/*
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* Change size of area pointed to by 'ptr' to 'size'.
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* If 'ptr' is NULL, then its a malloc(). If 'size' is 0, then its a free().
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* 'ptr' must be NULL or a pointer to a non-freed area previously returned by
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* simple_realloc() or simple_malloc().
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*/
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static void *simple_realloc(void *ptr, unsigned long size)
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{
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struct alloc_info *p;
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void *new;
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if (size == 0) {
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simple_free(ptr);
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return NULL;
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}
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if (ptr == NULL)
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return simple_malloc(size);
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p = simple_find_entry(ptr);
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if (p == NULL) /* ptr not from simple_malloc/simple_realloc */
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return NULL;
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if (size <= p->size) /* fits in current block */
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return ptr;
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new = simple_malloc(size);
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memcpy(new, ptr, p->size);
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simple_free(ptr);
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return new;
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}
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/*
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* Returns addr of first byte after heap so caller can see if it took
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* too much space. If so, change args & try again.
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*/
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void *simple_alloc_init(char *base, unsigned long heap_size,
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unsigned long granularity, unsigned long max_allocs)
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{
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unsigned long heap_base, tbl_size;
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heap_size = _ALIGN_UP(heap_size, granularity);
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alloc_min = granularity;
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tbl_entries = max_allocs;
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tbl_size = tbl_entries * sizeof(struct alloc_info);
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alloc_tbl = (struct alloc_info *)_ALIGN_UP((unsigned long)base, 8);
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memset(alloc_tbl, 0, tbl_size);
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heap_base = _ALIGN_UP((unsigned long)alloc_tbl + tbl_size, alloc_min);
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next_base = heap_base;
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space_left = heap_size;
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platform_ops.malloc = simple_malloc;
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platform_ops.free = simple_free;
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platform_ops.realloc = simple_realloc;
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return (void *)(heap_base + heap_size);
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}
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