gistfile1.txt

func checksumNoFoldTwoAccum(b []byte, initial uint64) uint64 {
	ac := initial
	var bc, bcarr uint64
	var carry uint64
	for len(b) >= 128 {
		// add in chunks of eight up to 128
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[:8]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[8:16]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[16:24]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[24:32]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[32:40]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[40:48]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[48:56]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[56:64]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[64:72]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[72:80]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[80:88]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[88:96]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[96:104]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[104:112]), bcarr)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[112:120]), carry)
		bc, bcarr = bits.Add64(bc, binary.BigEndian.Uint64(b[120:128]), bcarr)
		b = b[128:]
	}
	ac, carry = bits.Add64(ac, bc, carry)
	ac, carry = bits.Add64(ac, bcarr, carry)
	if len(b) >= 64 {
		// add in chunks of eight up to 64
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[:8]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[8:16]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[16:24]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[24:32]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[32:40]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[40:48]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[48:56]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[56:64]), carry)
		b = b[64:]
	}
	if len(b) >= 32 {
		// add in chunks of eight up to 32
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[:8]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[8:16]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[16:24]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[24:32]), carry)
		b = b[32:]
	}
	if len(b) >= 16 {
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[:8]), carry)
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[8:16]), carry)
		b = b[16:]
	}
	if len(b) >= 8 {
		ac, carry = bits.Add64(ac, binary.BigEndian.Uint64(b[:8]), carry)
		b = b[8:]
	}
	if len(b) >= 4 {
		ac, carry = bits.Add64(ac, uint64(binary.BigEndian.Uint32(b)), carry)
		b = b[4:]
	}
	if len(b) >= 2 {
		ac, carry = bits.Add64(ac, uint64(binary.BigEndian.Uint16(b)), carry)
		b = b[2:]
	}
	if len(b) == 1 {
		ac, carry = bits.Add64(ac, uint64(b[0])<<8, carry)
	}

	return ac + carry
}