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#include <assert.h>
#include <stddef.h> /* NULL, size_t */
#include <stdint.h> /* uintptr_t */
#ifndef MEMSIZE
#define MEMSIZE 1024*4*1024*1024l
#endif
#define unlikely(x) __builtin_expect((x),0)
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {
uintptr_t end = 0;
uintptr_t ptr = 0;
} bumpptr_t;
__thread bumpptr_t* tsd = NULL;
inline void init_tsd() {
void* mem_start = mmap(NULL, MEMSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
if(mem_start == MAP_FAILED) {
perror("mmap");
return NULL;
}
tsd = (bumpptr_t*)mem_start;
tsd->ptr = (uintptr_t)mem_start + sizeof(bumpptr_t);
tsd->end = (uintptr_t)mem_start + MEMSIZE;
}
inline void* bump_up(size_t size, size_t align) {
assert(align % 2 == 0);
if (unlikely(tsd == NULL)) {
init_tsd();
}
// align ptr;
uintptr_t aligned = (tsd->ptr + align - 1) & ~(align - 1);
uintptr_t new_ptr = aligned + size;
if (new_ptr > mem_end)
return NULL;
else {
tsd->ptr = new_ptr;
return (void*)aligned;
}
}
#ifdef __cplusplus
}
#endif
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