mix32.go

package main

import (
	"encoding/binary"
	"fmt"
	"io"
	"os"
)

// Mix32 is a quick-and-dirty 256-bit hash from 32-bit operations.
type Mix32 struct {
	s   [8]uint32
	buf [28]byte
	n   int
}

func (m *Mix32) mix() {
	m.buf[27] = byte(m.n)
	m.n = 0
	m.s[0] ^= binary.LittleEndian.Uint32(m.buf[0:])
	m.s[1] ^= binary.LittleEndian.Uint32(m.buf[4:])
	m.s[2] ^= binary.LittleEndian.Uint32(m.buf[8:])
	m.s[3] ^= binary.LittleEndian.Uint32(m.buf[12:])
	m.s[4] ^= binary.LittleEndian.Uint32(m.buf[16:])
	m.s[5] ^= binary.LittleEndian.Uint32(m.buf[20:])
	m.s[6] ^= binary.LittleEndian.Uint32(m.buf[24:])
	for r := 0; r < 2; r++ {
		for i := uint32(0); i < 8; i++ {
			j := (i + 7) % 8
			m.s[i] ^= i - m.s[j]
			m.s[i] *= 0x885a308d
			m.s[i] ^= m.s[i] >> 16
		}
	}
}

func (m *Mix32) Write(p []byte) (n int, err error) {
	n = len(p)

	if m.n > 0 {
		if m.n+len(p) < 27 {
			m.n += copy(m.buf[m.n:], p)
			return
		} else if m.n+len(p) >= 27 {
			v := copy(m.buf[m.n:], p)
			m.n = 27
			m.mix()
			p = p[v:]
		}
	}

	for len(p) >= 27 {
		copy(m.buf[0:], p)
		m.n = 27
		m.mix()
		p = p[27:]
	}
	m.n = copy(m.buf[0:], p)
	return
}

func (m *Mix32) Sum(b []byte) []byte {
	c := *m
	c.mix()
	var buf [32]byte
	binary.LittleEndian.PutUint32(buf[0:], c.s[0])
	binary.LittleEndian.PutUint32(buf[4:], c.s[1])
	binary.LittleEndian.PutUint32(buf[8:], c.s[2])
	binary.LittleEndian.PutUint32(buf[12:], c.s[3])
	binary.LittleEndian.PutUint32(buf[16:], c.s[4])
	binary.LittleEndian.PutUint32(buf[20:], c.s[5])
	binary.LittleEndian.PutUint32(buf[24:], c.s[6])
	binary.LittleEndian.PutUint32(buf[28:], c.s[7])
	return append(b, buf[:]...)
}

func (m *Mix32) Reset() {
	*m = Mix32{}
}

func (m *Mix32) Size() int {
	return 32
}

func (m *Mix32) BlockSize() int {
	return 27
}

func main() {
	var h Mix32
	io.Copy(&h, os.Stdin)
	s := h.Sum(nil)

	const scale = 32
	fmt.Printf("P1\n%d %d\n", 16*scale, 16*scale)
	for y := 0; y < 16*scale; y++ {
		by := y / scale
		for x := 0; x < 16*scale; x++ {
			bx := x / scale
			b := by*16 + bx
			fmt.Println(s[b/8] >> (b % 8) & 1)
		}
	}
}