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libkernaux/src/pfa.c

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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <kernaux/pfa.h>
#include <kernaux/stdlib.h>
static void KernAux_PFA_mark(
struct KernAux_PFA *pfa,
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bool status,
size_t start,
size_t end
)
__attribute__((nonnull));
void KernAux_PFA_initialize(struct KernAux_PFA *const pfa)
{
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kernaux_memset(pfa->pages, false, sizeof(pfa->pages));
}
void KernAux_PFA_mark_available(
struct KernAux_PFA *const pfa,
const size_t start,
const size_t end
) {
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KernAux_PFA_mark(pfa, true, start, end);
}
void KernAux_PFA_mark_unavailable(
struct KernAux_PFA *const pfa,
const size_t start,
const size_t end
) {
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KernAux_PFA_mark(pfa, false, start, end);
}
void KernAux_PFA_mark(
struct KernAux_PFA *const pfa,
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const bool status,
size_t start,
size_t end
) {
if (start >= end) return;
const size_t start_rem = start % KERNAUX_PFA_PAGE_SIZE;
const size_t end_rem = (end + 1) % KERNAUX_PFA_PAGE_SIZE;
if (start_rem != 0) {
start = start - start_rem + KERNAUX_PFA_PAGE_SIZE;
}
if (end_rem != 0) {
end = end - end_rem;
}
const size_t start_index = start / KERNAUX_PFA_PAGE_SIZE;
const size_t end_index = end / KERNAUX_PFA_PAGE_SIZE;
for (size_t index = start_index; index <= end_index; ++index) {
pfa->pages[index] = status;
}
}
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size_t KernAux_PFA_alloc_page(struct KernAux_PFA *const pfa)
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{
// We start from 1 because 0 indicates failure.
// It is not very usefull to alloc page at address 0;
//
for (size_t index = 1; index < KERNAUX_PFA_PAGES_COUNT_MAX; ++index) {
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if (pfa->pages[index]) {
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pfa->pages[index] = false;
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return index * KERNAUX_PFA_PAGE_SIZE;
}
}
return 0;
}
void KernAux_PFA_free_page(struct KernAux_PFA *const pfa, size_t page_addr)
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{
if (page_addr % KERNAUX_PFA_PAGE_SIZE != 0) return;
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pfa->pages[page_addr / KERNAUX_PFA_PAGE_SIZE] = true;
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}