
// 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/6/max/Max.asm

// Computes R2 = max(R0, R1)  (R0,R1,R2 refer to RAM[0],RAM[1],RAM[2])
// Usage: Before executing, put two values in R0 and R1.


  // D = R0 - R1

/*
  @R0
  D=M
  @R1
  D=D-M
  // If (D > 0) goto ITSR0
  @ITSR0
  D;JGT
  // Its R1
  @R1
  D=M
  @OUTPUT_D
  0;JMP
(ITSR0)
  @R0
  D=M
(OUTPUT_D)
  @R2
  M=D
(END)
  @END
  0;JMP

*/

// Max
// Takes two numbers and saves the highest of them
// Get the sum of R0 & R1
// Save it in R2
// Get Value of R0
// Compare it value of R1
// Remember that the conditional can only be compared to zero.
// GT. LS, EQ etc.. All to zero
// Create a label and jump to it

@R0
D=M // Value of R0
@R1
D=D-M // New D(playground) is Old D(Value of R0) Minus Value of R1. Basically R0 - R1
@ITSR0
D;JGT // If D (R0 - R1) is greater than 0, then R0 is biger. Otherwise R1 or equal.
// Else it R1
@R1 // Get The Value of R1
D=M
@OUTPUT_D // And send it to the output section which is R2 variable
0;JMP
// The end Statements
(ITSR0) // Jump here if R0
@R0
D=M // Set value of R0 to the playground variable.
(OUTPUT_D) // End up here either way. Depending on value.
@R2
M=D // Set R2 to D either way. Just with or without the ITSR0 iteration
(END) // Infinite loop - prevents CPU from executing undefined instructions.
@END
0;JMP // Infinite Jumping to end the program
