#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/time.h>
#include <openssl/sha.h>


static unsigned long long tb0[64];

static long long getnow()
{
	struct timeval tv;
	gettimeofday (&tv,NULL);
	return tv.tv_sec *1000000L + tv.tv_usec;
}

static void test_filltb0()
{
	unsigned long long v=(unsigned long long)0xffffffffffffffffl;
	for (unsigned i=0; i<64; i++){
		tb0[i] = v;
		v >>=1;
	}
	// for (unsigned i=0; i<16; i++) printf ("tb0[%u] = %016Lx\n",i,tb0[i]);
}

#if 0
static bool test_nbzero (int nb0, unsigned char *bufout)
{
	bool ret = false;
	if (nb0 == 0){
		ret = true;
	}else if (nb0 > 8){
		ret = bufout[0] == 0 && test_nbzero(nb0-8,bufout+1);
	}else{
		static unsigned char tb[]={
			00,0x7f
		};
		ret = bufout[0] < tb[nb0];	
	}
}
#endif
static bool test_nbzero (int nb0, const unsigned char *bufout)
{
	union {
		unsigned char c[8];
		unsigned long long v;
	}u;
	u.c[7] = bufout[0];
	u.c[6] = bufout[1];
	u.c[5] = bufout[2];
	u.c[4] = bufout[3];
	u.c[3] = bufout[4];
	u.c[2] = bufout[5];
	u.c[1] = bufout[6];
	u.c[0] = bufout[7];
	return tb0[nb0] > u.v;
}
int main (int argc, char *argv[])
{
	int ret = -1;
	if (argc == 2 && strcmp(argv[1],"genere")==0){
		FILE *fin = fopen ("/dev/urandom","r");
		if (fin == NULL){
			fprintf (stderr,"Can't open /dev/urandom (%s)\n",strerror(errno));
		}else{
			unsigned char buf[8];
			if (fread(buf,1,sizeof(buf),fin)!=sizeof(buf)){
				fprintf (stderr,"Read error (%s)\n",strerror(errno));
			}else{
				for (unsigned i=0; i<8; i++) printf ("%02x",buf[i]);
			}
			struct timeval tv;
			gettimeofday (&tv,NULL);
			printf ("%ld%ld\n",tv.tv_sec,tv.tv_usec);
			ret = 0;
			fclose (fin);
		}
	}else if (argc != 3){
		fprintf (stderr,"input nb0\n");
	}else{
		test_filltb0();
		int nb0 = atoi(argv[2]);
		long long start = getnow();
		int len = strlen(argv[1]);
		char buf[len+20];
		strcpy (buf,argv[1]);
		for (unsigned i=0; i<4000000000; i++){
			int n = sprintf (buf+len,",%u",i);

			SHA256_CTX ctx;
			SHA256_Init(&ctx);
			SHA256_Update(&ctx, buf, len+n);
			unsigned char bufout[BUFSIZ];
			SHA256_Final(bufout, &ctx);
			if (test_nbzero(nb0,bufout)){
				long long end = getnow();
				printf ("%lfs %lfsum/s nb0=%d tb0[nb0]=%016Lx %12u %s: ",(double)(end-start)/1000000,(i/(double)(end-start))*1000000,nb0,tb0[nb0],i,buf);
				for (unsigned j = 0; j < SHA256_DIGEST_LENGTH; j++){
					printf("%02x", bufout[j]);
				}
				putchar('\n');
				ret = 0;
				break;
			}
		}
	}
	return ret;
}