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#include <stdint.h>
#include <limits.h>
#include <stddef.h>
#include "memory.h"
#include "multiboot.h"
struct memory_area {
uint32_t len;
struct memory_area *next;
};
struct memory_area *first = NULL;
void init_memory(multiboot_info_t *mb) {
struct memory_area *prev = NULL;
for (
multiboot_memory_map_t *e = (multiboot_memory_map_t *) mb->mmap_addr;
(unsigned int) e < mb->mmap_addr + mb->mmap_length;
e += 1
) {
if (e->type != MULTIBOOT_MEMORY_AVAILABLE) continue;
// memory below 1MB is not safe to use.
if (e->addr < 1000000) continue;
// memory above UINT_MAX is unusable.
if (e->addr > UINT_MAX) continue;
uint32_t length;
// if the memory reaches outside of UINT_MAX, truncate length value
if (e->addr + e->len > UINT_MAX)
length = UINT_MAX - e->addr;
else length = e->len;
struct memory_area *cur = (struct memory_area *) e->addr;
cur->len = length;
if (prev != NULL)
prev->next = (struct memory_area *) e->addr;
prev = cur;
}
}
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