// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/02/ALU.hdl

/**
 * The ALU (Arithmetic Logic Unit).
 * Computes one of the following functions:
 * x+y, x-y, y-x, 0, 1, -1, x, y, -x, -y, !x, !y,
 * x+1, y+1, x-1, y-1, x&y, x|y on two 16-bit inputs, 
 * according to 6 input bits denoted zx,nx,zy,ny,f,no.
 * In addition, the ALU computes two 1-bit outputs:
 * if the ALU output == 0, zr is set to 1; otherwise zr is set to 0;
 * if the ALU output < 0, ng is set to 1; otherwise ng is set to 0.
 */

// Implementation: the ALU logic manipulates the x and y inputs
// and operates on the resulting values, as follows:
// if (zx == 1) set x = 0        // 16-bit constant
// if (nx == 1) set x = !x       // bitwise not
// if (zy == 1) set y = 0        // 16-bit constant
// if (ny == 1) set y = !y       // bitwise not
// if (f == 1)  set out = x + y  // integer 2's complement addition
// if (f == 0)  set out = x & y  // bitwise and
// if (no == 1) set out = !out   // bitwise not
// if (out == 0) set zr = 1
// if (out < 0) set ng = 1

CHIP ALU {
    IN  
        x[16], y[16],  // 16-bit inputs        
        zx, // zero the x input?
        nx, // negate the x input?
        zy, // zero the y input?
        ny, // negate the y input?
        f,  // compute out = x + y (if 1) or x & y (if 0)
        no; // negate the out output?

    OUT 
        out[16], // 16-bit output
        zr, // 1 if (out == 0), 0 otherwise
        ng; // 1 if (out < 0),  0 otherwise

    PARTS:
    // Put you code here:
    //zxがtrueのとき全部0にする
    Not(in=zx, out=nzx);
    
    //もっと効率いい書き方あるのかな？
    And16(a[0..15]=x[0..15], b[0]=nzx, b[1]=nzx, b[2]=nzx, b[3]=nzx, b[4]=nzx, b[5]=nzx, b[6]=nzx, b[7]=nzx, b[8]=nzx, b[9]=nzx, b[10]=nzx, b[11]=nzx, b[12]=nzx, b[13]=nzx, b[14]=nzx, b[15]=nzx, out[0..15]=w1x);
    //nxがtrueのとき全部反転する
    Xor16(a[0..15]=w1x, b[0]=nx, b[1]=nx, b[2]=nx, b[3]=nx, b[4]=nx, b[5]=nx, b[6]=nx, b[7]=nx, b[8]=nx, b[9]=nx, b[10]=nx, b[11]=nx, b[12]=nx, b[13]=nx, b[14]=nx, b[15]=nx, out[0..15]=w2x);
    
    //zyがtrueのとき全部0にする
    Not(in=zy, out=nzy);
    And16(a[0..15]=y[0..15], b[0]=nzy, b[1]=nzy, b[2]=nzy, b[3]=nzy, b[4]=nzy, b[5]=nzy, b[6]=nzy, b[7]=nzy, b[8]=nzy, b[9]=nzy, b[10]=nzy, b[11]=nzy, b[12]=nzy, b[13]=nzy, b[14]=nzy, b[15]=nzy, out[0..15]=w1y);
    //nyがtrueのとき全部反転する
    Xor16(a[0..15]=w1y, b[0]=ny, b[1]=ny, b[2]=ny, b[3]=ny, b[4]=ny, b[5]=ny, b[6]=ny, b[7]=ny, b[8]=ny, b[9]=ny, b[10]=ny, b[11]=ny, b[12]=ny, b[13]=ny, b[14]=ny, b[15]=ny, out[0..15]=w2y);
    
    //加算
    Add16(a[0..15]=w2x, b[0..15]=w2y, out[0..15]=wadd);
    //ANDビット演算
    And16(a[0..15]=w2x, b[0..15]=w2y, out[0..15]=wand);
    //加算かANDか選ぶ
    Mux16(a[0..15]=wand, b[0..15]=wadd, sel=f, out[0..15]=wcal);
    
    //noがtrueのとき全部反転する
    Xor16(a[0..15]=wcal, b[0]=no, b[1]=no, b[2]=no, b[3]=no, b[4]=no, b[5]=no, b[6]=no, b[7]=no, b[8]=no, b[9]=no, b[10]=no, b[11]=no, b[12]=no, b[13]=no, b[14]=no, b[15]=no, out[0..15]=wres, out[0..15]=out[0..15], out[15]=ng);
    
    //
    Or16to1(a=wres, out=nzr);
    Not(in=nzr, out=zr);
    
}