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#include <assert.h>
#include <errno.h>
#include <stddef.h> /* NULL, size_t */
#include <stdint.h> /* uintptr_t */
#include <stdio.h> /* uintptr_t */
#include <unistd.h> /* sysconf(_SC_PAGESIZE) */
#include <string.h> /* memset */
#include <sys/mman.h> /* memset */
#define MIN_ALIGNMENT 16
#ifndef MEMSIZE
#define MEMSIZE 1024*4*1024*1024l
#endif
#define unlikely(x) __builtin_expect((x),0)
#ifdef __cplusplus
extern "C" {
#endif
__thread void* mem_start = NULL;
__thread uintptr_t mem_end = 0;
__thread uintptr_t ptr = 0;
inline void* bump_up(size_t size, size_t align) {
assert(align % 2 == 0);
if (unlikely(mem_start == NULL)) {
mem_start = mmap(NULL, MEMSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if(mem_start == MAP_FAILED) {
perror("mmap");
return NULL;
}
ptr = (uintptr_t)mem_start;
mem_end = ptr + MEMSIZE;
}
// align ptr;
uintptr_t aligned = (ptr + align - 1) & ~(align - 1);
uintptr_t new_ptr = aligned + size;
if (new_ptr > mem_end)
return NULL;
else {
ptr = new_ptr;
return (void*)aligned;
}
}
void* malloc(size_t size) {
return bump_up(size, MIN_ALIGNMENT);
}
void free(__attribute__ ((unused)) void* ptr) {
}
void* realloc(void* ptr, size_t size) {
if(ptr == NULL)
return malloc(size);
void* new_ptr = bump_up(size, MIN_ALIGNMENT);
// this may copies to much
memcpy(new_ptr, ptr, size);
return new_ptr;
}
void* memalign(size_t alignment, size_t size) {
return bump_up(size, alignment);
}
int posix_memalign(void **memptr, size_t alignment, size_t size)
{
void *out;
if(memptr == NULL) {
return 22;
}
if((alignment % sizeof(void*)) != 0) {
return 22;
}
/* if not power of two */
if(!((alignment != 0) && !(alignment & (alignment - 1)))) {
return 22;
}
if(size == 0) {
*memptr = NULL;
return 0;
}
out = bump_up(size, alignment);
if(out == NULL) {
return 12;
}
*memptr = out;
return 0;
}
void* calloc(size_t nmemb, size_t size)
{
void *out;
size_t fullsize = nmemb * size;
if((size != 0) && ((fullsize / size) != nmemb)) {
return NULL;
}
out = bump_up(fullsize, MIN_ALIGNMENT);
if(out == NULL) {
return NULL;
}
memset(out, 0, fullsize);
return out;
}
void* valloc(size_t size)
{
long ret = sysconf(_SC_PAGESIZE);
if(ret == -1) {
return NULL;
}
return memalign(ret, size);
}
void* pvalloc(size_t size)
{
size_t ps, rem, allocsize;
long ret = sysconf(_SC_PAGESIZE);
if(ret == -1) {
return NULL;
}
ps = ret;
rem = size % ps;
allocsize = size;
if(rem != 0) {
allocsize = ps + (size - rem);
}
return memalign(ps, allocsize);
}
void* aligned_alloc(size_t alignment, size_t size)
{
if(alignment > size) {
return NULL;
}
if((size % alignment) != 0) {
return NULL;
}
return memalign(alignment, size);
}
int malloc_stats() {
fprintf(stderr, "Bump pointer allocator by muhq\n");
fprintf(stderr, "Memsize: %zu, start address: %p, bump pointer %p\n", MEMSIZE, mem_start, ptr);
return 0;
}
#ifdef __cplusplus
}
#endif
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