#include <stdio.h>
#include <stdint.h>

#define ADLER32_INITIAL 0x00000001ul

uint_least32_t adler32(uint_least32_t ck, const void *data, size_t len) {
	unsigned a, b;
	size_t sublen;

	a=ck&0xffff;
	b=(ck>>16)&0xffff;
	
	while(len>0) {
		sublen=len>5552?5552:len;
		len-=sublen;
		while(sublen--) {
			a+=*(char*)data;
			data=(char*)data+1;
			b+=a;
		}
		a%=65521;
		b%=65521;
	}
	return ((uint_least32_t)b<<16)|a;
}

int main(void) {
	char buf[50];
	size_t cnt;	
	uint_least32_t ck;

	ck=ADLER32_INITIAL;
	do {
		cnt=fread(buf, 1, sizeof buf, stdin);
		if(ferror(stdin)) {
			perror("fread()");
			return 0;
		}
		ck=adler32(ck, buf, cnt);
	} while(!feof(stdin));
	printf("adler32 = 0x%08x\n", ck);
	return 1;
}