#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/wait.h>

struct meta {
	struct meta *prev, *next;
	struct group *mem;
	volatile int avail_mask, freed_mask;
	uintptr_t last_idx:5;
	uintptr_t freeable:1;
	uintptr_t sizeclass:6;
	uintptr_t maplen:8*sizeof(uintptr_t)-12;
};

const uint16_t size_classes[] = {
	1, 2, 3, 4, 5, 6, 7, 8,
	9, 10, 12, 15,
	18, 20, 25, 31,
	36, 42, 50, 63,
	72, 84, 102, 127,
	146, 170, 204, 255,
	292, 340, 409, 511,
	584, 682, 818, 1023,
	1169, 1364, 1637, 2047,
	2340, 2730, 3276, 4095,
	4680, 5460, 6552, 8191,
};

void runtest(size_t size)
{
	pid_t pid;
	if ((pid=fork())) {
		waitpid(pid, 0, 0);
		return;
	}
	unsigned char *p, *ptrs[200];
	printf("%5zu: ", size);
	for (int i=0; i<sizeof ptrs / sizeof *ptrs; i++) {
		ptrs[i] = p = malloc(size);
		int idx = p[-3] & 31;
		struct meta *m = *(struct meta **)(p-16-*(uint16_t *)(p-2)*16);
		if (idx==0) {
			if (!m->maplen || m->maplen*4096UL>=size_classes[m->sizeclass]*16+16)
				printf(" %2dx%-5d", m->last_idx+1, size_classes[m->sizeclass]*16);
			else
				printf(" %7luk", m->maplen*4UL);
		} else {
			//printf("[        ]");
		}
	}
	for (int i=0; i<sizeof ptrs / sizeof *ptrs; i++) free(ptrs[i]);
	printf("\n");
	exit(0);
}

int main() {
	if (1) for (int i=0; i<44; i++) {
		size_t size = size_classes[i]*16;
		runtest(size-4);
		size_t pgaligned = (size+4095) & -4096;
		if (pgaligned != size+16 && pgaligned < size_classes[i+1]*16)
			runtest(pgaligned-20);
	}
//	runtest(4076);
//	runtest(4076);
//	runtest(4076);
}