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Changed heap to use naturally aligned start address and added near-fit case to #17922 fix.

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This commit is contained in:
christiaans 2006-11-27 14:23:24 +00:00
parent 77e0f77850
commit 976bce4c7f
1 changed files with 16 additions and 21 deletions
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37
src/core/mem.c
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@ -63,7 +63,8 @@ struct mem {
};
static struct mem *ram_end;
static u8_t ram[MEM_SIZE + sizeof(struct mem) + MEM_ALIGNMENT];
static u8_t *ram;
static struct mem ram_heap[1 + ( (MEM_SIZE + sizeof(struct mem) - 1) / sizeof(struct mem))];
#define MIN_SIZE 12
#if 0 /* this one does not align correctly for some, resulting in crashes */
@ -116,6 +117,7 @@ mem_init(void)
{
struct mem *mem;
ram = (u8_t*)ram_heap;
memset(ram, 0, MEM_SIZE);
mem = (struct mem *)ram;
mem->next = MEM_SIZE;
@ -305,11 +307,7 @@ mem_malloc(mem_size_t size)
}
#else
/**
* Adam's mem_malloc() plus changes made by Christiaan.
* Work in progress based on bug #17922 report by Tom Hennen.
*
* @note this passes the supplied testcase but we suspect more bugs.
* Therefore we call for more brains, reviewers and testers!
* Adam's mem_malloc() plus solution for bug #17922
*/
void *
mem_malloc(mem_size_t size)
@ -333,22 +331,15 @@ mem_malloc(mem_size_t size)
sys_sem_wait(mem_sem);
/* @todo is the change from MEM_SIZE to MEM_SIZE - size correct? */
for (ptr = (u8_t *)lfree - ram; ptr < MEM_SIZE - size; ptr = ((struct mem *)&ram[ptr])->next) {
mem = (struct mem *)&ram[ptr];
if (!mem->used) {
ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
if (mem->next - (ptr + SIZEOF_STRUCT_MEM) == size) {
/* exact fit, do not split, no mem2 creation */
mem->next = ptr2;
mem->used = 1;
}
else if (mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) > size) {
if (mem->next - (ptr + (2*SIZEOF_STRUCT_MEM)) > size) {
/* split large block, create empty remainder */
/* @todo do we need to ensure the remainder can
house a minimal sized (aligned) unit? */
mem->next = ptr2;
mem->used = 1;
/* create mem2 struct */
@ -360,13 +351,17 @@ mem_malloc(mem_size_t size)
if (mem2->next != MEM_SIZE) {
((struct mem *)&ram[mem2->next])->prev = ptr2;
}
}
else
{
/* @todo: what if we have a near fit
(block > size && block < size + SIZEOF_STRUCT_MEM).
Round size up? Or do we need to continue to next block for "first fit"? */
else if (mem->next - (ptr + SIZEOF_STRUCT_MEM) > size) {
/* near fit, no split, no mem2 creation,
round up to mem->next */
ptr2 = mem->next;
mem->used = 1;
}
else if (mem->next - (ptr + SIZEOF_STRUCT_MEM) == size) {
/* exact fit, do not split, no mem2 creation */
mem->next = ptr2;
mem->used = 1;
}
if (mem->used) {