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mem.c: beautify converting between struct mem and heap index (add ptr_to_mem/mem_to_ptr)

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This commit is contained in:
goldsimon 2017-09-26 22:13:44 +02:00
parent 1710fc1a89
commit a61aee337b
1 changed files with 33 additions and 22 deletions
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55
src/core/mem.c
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@ -337,6 +337,17 @@ static volatile u8_t mem_free_count;
#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
static struct mem *
ptr_to_mem(mem_size_t ptr)
{
return (struct mem *)(void *)&ram[ptr];
}
static mem_size_t
mem_to_ptr(void *mem)
{
return (mem_size_t)((u8_t *)mem - ram);
}
/**
* "Plug holes" by combining adjacent empty struct mems.
@ -362,25 +373,25 @@ plug_holes(struct mem *mem)
/* plug hole forward */
LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE_ALIGNED", mem->next <= MEM_SIZE_ALIGNED);
nmem = (struct mem *)(void *)&ram[mem->next];
nmem = ptr_to_mem(mem->next);
if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end) {
/* if mem->next is unused and not end of ram, combine mem and mem->next */
if (lfree == nmem) {
lfree = mem;
}
mem->next = nmem->next;
((struct mem *)(void *)&ram[nmem->next])->prev = (mem_size_t)((u8_t *)mem - ram);
ptr_to_mem(nmem->next)->prev = mem_to_ptr(mem);
}
/* plug hole backward */
pmem = (struct mem *)(void *)&ram[mem->prev];
pmem = ptr_to_mem(mem->prev);
if (pmem != mem && pmem->used == 0) {
/* if mem->prev is unused, combine mem and mem->prev */
if (lfree == mem) {
lfree = pmem;
}
pmem->next = mem->next;
((struct mem *)(void *)&ram[mem->next])->prev = (mem_size_t)((u8_t *)pmem - ram);
ptr_to_mem(mem->next)->prev = mem_to_ptr(pmem);
}
}
@ -403,7 +414,7 @@ mem_init(void)
mem->prev = 0;
mem->used = 0;
/* initialize the end of the heap */
ram_end = (struct mem *)(void *)&ram[MEM_SIZE_ALIGNED];
ram_end = ptr_to_mem(MEM_SIZE_ALIGNED);
ram_end->used = 1;
ram_end->next = MEM_SIZE_ALIGNED;
ram_end->prev = MEM_SIZE_ALIGNED;
@ -426,9 +437,9 @@ mem_link_valid(struct mem *mem)
{
struct mem *nmem, *pmem;
mem_size_t rmem_idx;
rmem_idx = (mem_size_t)((u8_t *)mem - ram);
nmem = (struct mem *)(void *)&ram[mem->next];
pmem = (struct mem *)(void *)&ram[mem->prev];
rmem_idx = mem_to_ptr(mem);
nmem = ptr_to_mem(mem->next);
pmem = ptr_to_mem(mem->prev);
if ((mem->next > MEM_SIZE_ALIGNED) || (mem->prev > MEM_SIZE_ALIGNED) ||
((mem->prev != rmem_idx) && (pmem->next != rmem_idx)) ||
((nmem != ram_end) && (nmem->prev != rmem_idx))) {
@ -555,7 +566,7 @@ mem_trim(void *rmem, mem_size_t new_size)
/* cast through void* to get rid of alignment warnings */
mem = (struct mem *)(void *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);
/* ... and its offset pointer */
ptr = (mem_size_t)((u8_t *)mem - ram);
ptr = mem_to_ptr(mem);
size = (mem_size_t)((mem_size_t)(mem->next - ptr) - SIZEOF_STRUCT_MEM);
LWIP_ASSERT("mem_trim can only shrink memory", newsize <= size);
@ -571,7 +582,7 @@ mem_trim(void *rmem, mem_size_t new_size)
/* protect the heap from concurrent access */
LWIP_MEM_FREE_PROTECT();
mem2 = (struct mem *)(void *)&ram[mem->next];
mem2 = ptr_to_mem(mem->next);
if (mem2->used == 0) {
/* The next struct is unused, we can simply move it at little */
mem_size_t next;
@ -580,9 +591,9 @@ mem_trim(void *rmem, mem_size_t new_size)
/* create new struct mem which is moved directly after the shrinked mem */
ptr2 = (mem_size_t)(ptr + SIZEOF_STRUCT_MEM + newsize);
if (lfree == mem2) {
lfree = (struct mem *)(void *)&ram[ptr2];
lfree = ptr_to_mem(ptr2);
}
mem2 = (struct mem *)(void *)&ram[ptr2];
mem2 = ptr_to_mem(ptr2);
mem2->used = 0;
/* restore the next pointer */
mem2->next = next;
@ -594,7 +605,7 @@ mem_trim(void *rmem, mem_size_t new_size)
* let 'mem2->next->prev' point to mem2 again. but only if mem2->next is not
* the end of the heap */
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
ptr_to_mem(mem2->next)->prev = ptr2;
}
MEM_STATS_DEC_USED(used, (size - newsize));
/* no need to plug holes, we've already done that */
@ -607,7 +618,7 @@ mem_trim(void *rmem, mem_size_t new_size)
* region that couldn't hold data, but when mem->next gets freed,
* the 2 regions would be combined, resulting in more free memory */
ptr2 = (mem_size_t)(ptr + SIZEOF_STRUCT_MEM + newsize);
mem2 = (struct mem *)(void *)&ram[ptr2];
mem2 = ptr_to_mem(ptr2);
if (mem2 < lfree) {
lfree = mem2;
}
@ -616,7 +627,7 @@ mem_trim(void *rmem, mem_size_t new_size)
mem2->prev = ptr;
mem->next = ptr2;
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
ptr_to_mem(mem2->next)->prev = ptr2;
}
MEM_STATS_DEC_USED(used, (size - newsize));
/* the original mem->next is used, so no need to plug holes! */
@ -681,9 +692,9 @@ mem_malloc(mem_size_t size_in)
/* Scan through the heap searching for a free block that is big enough,
* beginning with the lowest free block.
*/
for (ptr = (mem_size_t)((u8_t *)lfree - ram); ptr < MEM_SIZE_ALIGNED - size;
ptr = ((struct mem *)(void *)&ram[ptr])->next) {
mem = (struct mem *)(void *)&ram[ptr];
for (ptr = mem_to_ptr(lfree); ptr < MEM_SIZE_ALIGNED - size;
ptr = ptr_to_mem(ptr)->next) {
mem = ptr_to_mem(ptr);
#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
mem_free_count = 0;
LWIP_MEM_ALLOC_UNPROTECT();
@ -715,7 +726,7 @@ mem_malloc(mem_size_t size_in)
*/
ptr2 = (mem_size_t)(ptr + SIZEOF_STRUCT_MEM + size);
/* create mem2 struct */
mem2 = (struct mem *)(void *)&ram[ptr2];
mem2 = ptr_to_mem(ptr2);
mem2->used = 0;
mem2->next = mem->next;
mem2->prev = ptr;
@ -724,7 +735,7 @@ mem_malloc(mem_size_t size_in)
mem->used = 1;
if (mem2->next != MEM_SIZE_ALIGNED) {
((struct mem *)(void *)&ram[mem2->next])->prev = ptr2;
ptr_to_mem(mem2->next)->prev = ptr2;
}
MEM_STATS_INC_USED(used, (size + SIZEOF_STRUCT_MEM));
} else {
@ -736,7 +747,7 @@ mem_malloc(mem_size_t size_in)
* will always be used at this point!
*/
mem->used = 1;
MEM_STATS_INC_USED(used, mem->next - (mem_size_t)((u8_t *)mem - ram));
MEM_STATS_INC_USED(used, mem->next - mem_to_ptr(mem));
}
#if LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT
mem_malloc_adjust_lfree:
@ -756,7 +767,7 @@ mem_malloc_adjust_lfree:
goto mem_malloc_adjust_lfree;
}
#endif /* LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT */
cur = (struct mem *)(void *)&ram[cur->next];
cur = ptr_to_mem(cur->next);
}
lfree = cur;
LWIP_ASSERT("mem_malloc: !lfree->used", ((lfree == ram_end) || (!lfree->used)));