#include <stdio.h>
#include <stdlib.h>
#include <time.h>

typedef unsigned long long u64;

u64 GetTimeNS() { struct timespec time; clock_gettime(CLOCK_REALTIME, &time); return time.tv_sec*1000000000 + time.tv_nsec; }

//returns amount of characters or -1 for error. Digits only, this does not handle - or + at the start
int ParseInt(const char*sz, u64*out)
{
	if (!sz) return -1;
	u64 val=0; //overflow is legal with unsigned
	int i=0;
	while (1)
	{
		char c = sz[i];
		if ((unsigned)(c-'0') > 9u) break;
		u64 prevVal = val;
		val = val*10+c-'0';
		if (val <= prevVal && val != 0) {
			return -1;
		}
		i++;
	}
	if (i == 0)
		return -1;
	*out = val;
	return i;
}


int main(int argc, char *argv[])
{
	int arraySize=4096;
	char*array = (char*)realloc(0, arraySize);

	FILE*f = fopen("/tmp/numbers", "rb");
	if (f == 0) {
		return EXIT_FAILURE;
	}

	char buf[32];
	int i=0;
	u64 getLineTime=0;
	for(; ; i++)
	{
		getLineTime -= GetTimeNS();
		char*result = fgets(buf, sizeof(buf), f);
		getLineTime += GetTimeNS();
		if (result == 0) {
			break;
		}
		if (i+1 == arraySize) {
			arraySize *= 2;
			array = (char*)realloc(array, arraySize);
		}
		//array[i] = (atoi(buf) & 7) + '0';
		u64 value;
		ParseInt(buf, &value);
		array[i] = (char)(value & 7) + '0';
	}
	array[i++] = '\n';
	fwrite(array, 1, i, stdout);
	fprintf(stderr, "fgets time is %lldms\n", getLineTime/1000000);
}