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libkernaux
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Rewrite PFA

This commit is contained in:
Alex Kotov 2021-12-14 06:21:47 +05:00
parent 98c7db3f13
commit c987d0e63d
Signed by: kotovalexarian
GPG Key ID: 553C0EBBEB5D5F08
2 changed files with 18 additions and 36 deletions
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11
include/kernaux/pfa.h
View File

@ -11,6 +11,11 @@ extern "C" {
#define KERNAUX_PFA_PAGE_SIZE (4 * 1024)
#define KERNAUX_PFA_PAGES_COUNT_MAX (1024 * 1024)
#define KernAux_PFA_alloc_page(pfa) \
(KernAux_PFA_alloc_pages((pfa), KERNAUX_PFA_PAGE_SIZE))
#define KernAux_PFA_free_page(pfa, page_addr) \
(KernAux_PFA_free_pages((pfa), (page_addr), KERNAUX_PFA_PAGE_SIZE))
typedef struct KernAux_PFA *KernAux_PFA;
struct KernAux_PFA {
@ -29,15 +34,9 @@ __attribute__((nonnull));
void KernAux_PFA_mark_unavailable(KernAux_PFA pfa, size_t start, size_t end)
__attribute__((nonnull));
size_t KernAux_PFA_alloc_page(KernAux_PFA pfa)
__attribute__((nonnull));
size_t KernAux_PFA_alloc_pages(KernAux_PFA pfa, size_t mem_size)
__attribute__((nonnull));
void KernAux_PFA_free_page(KernAux_PFA pfa, size_t page_addr)
__attribute__((nonnull));
void KernAux_PFA_free_pages(KernAux_PFA pfa, size_t page_addr, size_t mem_size)
__attribute__((nonnull));

43
src/pfa.c
View File

@ -68,53 +68,36 @@ void KernAux_PFA_mark(
}
}
size_t KernAux_PFA_alloc_page(const KernAux_PFA pfa)
{
// We start from 1 because 0 indicates failure.
// It is not very useful to alloc page at address 0;
for (size_t index = 1; index < KERNAUX_PFA_PAGES_COUNT_MAX; ++index) {
if (pfa->pages[index]) {
pfa->pages[index] = false;
return index * KERNAUX_PFA_PAGE_SIZE;
}
}
return 0;
}
size_t KernAux_PFA_alloc_pages(const KernAux_PFA pfa, const size_t mem_size)
{
if (mem_size % KERNAUX_PFA_PAGE_SIZE != 0) return 0;
const size_t pages_count = mem_size / KERNAUX_PFA_PAGE_SIZE;
const size_t pages_count = mem_size / KERNAUX_PFA_PAGE_SIZE;
// We start from 1 because 0 indicates failure.
// It is not very useful to alloc page at address 0;
for (size_t start = 1; start < KERNAUX_PFA_PAGES_COUNT_MAX;) {
size_t end = start;
for (; end < start + pages_count; ++end) {
if (!pfa->pages[end]) break;
for (size_t index = 1, start = 0;
index < KERNAUX_PFA_PAGES_COUNT_MAX;
++index)
{
if (!pfa->pages[index]) {
start = 0;
continue;
}
if (end >= KERNAUX_PFA_PAGES_COUNT_MAX) return 0;
if (end == start + pages_count - 1) {
for (size_t index = start; index <= end; ++index) {
if (start == 0) start = index;
if (index - start + 1 == pages_count) {
for (; index >= start; --index) {
pfa->pages[index] = false;
}
return start * KERNAUX_PFA_PAGE_SIZE;
}
start = end + 1;
}
return 0;
}
void KernAux_PFA_free_page(const KernAux_PFA pfa, size_t page_addr)
{
if (page_addr % KERNAUX_PFA_PAGE_SIZE != 0) return;
pfa->pages[page_addr / KERNAUX_PFA_PAGE_SIZE] = true;
}
void KernAux_PFA_free_pages(
const KernAux_PFA pfa,
const size_t page_addr,