Complete project 2

Assignments/2_Boolean_Arithmetic/ALU.hdl

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+// 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/2/ALU.hdl
+/**
+ * ALU (Arithmetic Logic Unit):
+ * Computes out = one of the following functions:
+ *                0, 1, -1,
+ *                x, y, !x, !y, -x, -y,
+ *                x + 1, y + 1, x - 1, y - 1,
+ *                x + y, x - y, y - x,
+ *                x & y, x | y
+ * on the 16-bit inputs x, y,
+ * according to the input bits zx, nx, zy, ny, f, no.
+ * In addition, computes the two output bits:
+ * if (out == 0) zr = 1, else zr = 0
+ * if (out < 0)  ng = 1, else ng = 0
+ */
+// Implementation: Manipulates the x and y inputs
+// and operates on the resulting values, as follows:
+// if (zx == 1) sets x = 0        // 16-bit constant
+// if (nx == 1) sets x = !x       // bitwise not
+// if (zy == 1) sets y = 0        // 16-bit constant
+// if (ny == 1) sets y = !y       // bitwise not
+// if (f == 1)  sets out = x + y  // integer 2's complement addition
+// if (f == 0)  sets out = x & y  // bitwise and
+// if (no == 1) sets out = !out   // bitwise not
+
+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) or (out = x & y)?
+        no; // negate the out output?
+    OUT 
+        out[16], // 16-bit output
+        zr,      // if (out == 0) equals 1, else 0
+        ng;      // if (out < 0)  equals 1, else 0
+
+    PARTS:
+    Mux16(a=x, b=false, sel=zx, out=zxr);
+    Not16(in=zxr, out=nxr);
+    Mux16(a=zxr, b=nxr, sel=nx, out=xr);
+
+    Mux16(a=y, b=false, sel=zy, out=zyr);
+    Not16(in=zyr, out=nyr);
+    Mux16(a=zyr, b=nyr, sel=ny, out=yr);
+
+    Add16(a=xr, b=yr, out=s);
+    And16(a=xr, b=yr, out=a);
+    Mux16(a=a, b=s, sel=f, out=r);
+
+    Not16(in=r, out=nr);
+    Mux16(a=r, b=nr, sel=no, out=out, out[15]=ng, out[0..7]=r1, out[8..15]=r2);
+
+    Or8Way(in=r1, out=o1);
+    Or8Way(in=r2, out=o2);
+    Or(a=o1, b=o2, out=nzr);
+    Not(in=nzr, out=zr);
+
+}

Assignments/2_Boolean_Arithmetic/Add16.hdl

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+// 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/2/Add16.hdl
+/**
+ * 16-bit adder: Adds two 16-bit two's complement values.
+ * The most significant carry bit is ignored.
+ */
+CHIP Add16 {
+    IN a[16], b[16];
+    OUT out[16];
+
+    PARTS:
+    HalfAdder(a=a[0], b=b[0], sum=out[0], carry=c1);
+    FullAdder(a=a[1], b=b[1], c=c1, sum=out[1], carry=c2);
+    FullAdder(a=a[2], b=b[2], c=c2, sum=out[2], carry=c3);
+    FullAdder(a=a[3], b=b[3], c=c3, sum=out[3], carry=c4);
+    FullAdder(a=a[4], b=b[4], c=c4, sum=out[4], carry=c5);
+    FullAdder(a=a[5], b=b[5], c=c5, sum=out[5], carry=c6);
+    FullAdder(a=a[6], b=b[6], c=c6, sum=out[6], carry=c7);
+    FullAdder(a=a[7], b=b[7], c=c7, sum=out[7], carry=c8);
+    FullAdder(a=a[8], b=b[8], c=c8, sum=out[8], carry=c9);
+    FullAdder(a=a[9], b=b[9], c=c9, sum=out[9], carry=c10);
+    FullAdder(a=a[10], b=b[10], c=c10, sum=out[10], carry=c11);
+    FullAdder(a=a[11], b=b[11], c=c11, sum=out[11], carry=c12);
+    FullAdder(a=a[12], b=b[12], c=c12, sum=out[12], carry=c13);
+    FullAdder(a=a[13], b=b[13], c=c13, sum=out[13], carry=c14);
+    FullAdder(a=a[14], b=b[14], c=c14, sum=out[14], carry=c15);
+    FullAdder(a=a[15], b=b[15], c=c15, sum=out[15], carry=c16);
+}

Assignments/2_Boolean_Arithmetic/FullAdder.hdl

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+// 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/2/FullAdder.hdl
+/**
+ * Computes the sum of three bits.
+ */
+CHIP FullAdder {
+    IN a, b, c;  // 1-bit inputs
+    OUT sum,     // Right bit of a + b + c
+        carry;   // Left bit of a + b + c
+
+    PARTS:
+    HalfAdder(a=a, b=b, sum=x, carry=c1);
+    HalfAdder(a=x, b=c, sum=sum, carry=c2);
+    Or(a=c1, b=c2, out=carry);
+}

Assignments/2_Boolean_Arithmetic/HalfAdder.hdl

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+// 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/2/HalfAdder.hdl
+/**
+ * Computes the sum of two bits.
+ */
+CHIP HalfAdder {
+    IN a, b;    // 1-bit inputs
+    OUT sum,    // Right bit of a + b 
+        carry;  // Left bit of a + b
+
+    PARTS:
+    Xor(a=a, b=b, out=sum);
+    And(a=a, b=b, out=carry);
+}

Assignments/2_Boolean_Arithmetic/Inc16.hdl

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+// 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/2/Inc16.hdl
+/**
+ * 16-bit incrementer:
+ * out = in + 1
+ */
+CHIP Inc16 {
+    IN in[16];
+    OUT out[16];
+
+    PARTS:
+    Add16(a=in, b[0]=true, b[1..15]=false, out=out);
+}