2019 day 5 init (with day 2 code)

2019/day05/README.org

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+** --- Day 5: Sunny with a Chance of Asteroids ---
+You're starting to sweat as the ship makes its way toward Mercury. The
+Elves suggest that you get the air conditioner working by upgrading your
+ship computer to support the Thermal Environment Supervision Terminal.
+
+The Thermal Environment Supervision Terminal (TEST) starts by running a
+/diagnostic program/ (your puzzle input). The TEST diagnostic program
+will run on [[file:2][your existing Intcode computer]] after a few
+modifications:
+
+/First/, you'll need to add /two new instructions/:
+
+- Opcode =3= takes a single integer as /input/ and saves it to the
+  position given by its only parameter. For example, the instruction
+  =3,50= would take an input value and store it at address =50=.
+- Opcode =4= /outputs/ the value of its only parameter. For example, the
+  instruction =4,50= would output the value at address =50=.
+
+Programs that use these instructions will come with documentation that
+explains what should be connected to the input and output. The program
+=3,0,4,0,99= outputs whatever it gets as input, then halts.
+
+/Second/, you'll need to add support for /parameter modes/:
+
+Each parameter of an instruction is handled based on its parameter mode.
+Right now, your ship computer already understands parameter mode =0=,
+/position mode/, which causes the parameter to be interpreted as a
+/position/ - if the parameter is =50=, its value is /the value stored at
+address =50= in memory/. Until now, all parameters have been in position
+mode.
+
+Now, your ship computer will also need to handle parameters in mode =1=,
+/immediate mode/. In immediate mode, a parameter is interpreted as a
+/value/ - if the parameter is =50=, its value is simply /=50=/.
+
+Parameter modes are stored in the same value as the instruction's
+opcode. The opcode is a two-digit number based only on the ones and tens
+digit of the value, that is, the opcode is the rightmost two digits of
+the first value in an instruction. Parameter modes are single digits,
+one per parameter, read right-to-left from the opcode: the first
+parameter's mode is in the hundreds digit, the second parameter's mode
+is in the thousands digit, the third parameter's mode is in the
+ten-thousands digit, and so on. Any missing modes are =0=.
+
+For example, consider the program =1002,4,3,4,33=.
+
+The first instruction, =1002,4,3,4=, is a /multiply/ instruction - the
+rightmost two digits of the first value, =02=, indicate opcode =2=,
+multiplication. Then, going right to left, the parameter modes are =0=
+(hundreds digit), =1= (thousands digit), and =0= (ten-thousands digit,
+not present and therefore zero):
+
+#+BEGIN_EXAMPLE
+  ABCDE
+   1002
+
+  DE - two-digit opcode,      02 == opcode 2
+   C - mode of 1st parameter,  0 == position mode
+   B - mode of 2nd parameter,  1 == immediate mode
+   A - mode of 3rd parameter,  0 == position mode,
+                                    omitted due to being a leading zero
+#+END_EXAMPLE
+
+This instruction multiplies its first two parameters. The first
+parameter, =4= in position mode, works like it did before - its value is
+the value stored at address =4= (=33=). The second parameter, =3= in
+immediate mode, simply has value =3=. The result of this operation,
+=33 * 3 = 99=, is written according to the third parameter, =4= in
+position mode, which also works like it did before - =99= is written to
+address =4=.
+
+Parameters that an instruction writes to will /never be in immediate
+mode/.
+
+/Finally/, some notes:
+
+- It is important to remember that the instruction pointer should
+  increase by /the number of values in the instruction/ after the
+  instruction finishes. Because of the new instructions, this amount is
+  no longer always =4=.
+- Integers can be negative: =1101,100,-1,4,0= is a valid program (find
+  =100 + -1=, store the result in position =4=).
+
+The TEST diagnostic program will start by requesting from the user the
+ID of the system to test by running an /input/ instruction - provide it
+=1=, the ID for the ship's air conditioner unit.
+
+It will then perform a series of diagnostic tests confirming that
+various parts of the Intcode computer, like parameter modes, function
+correctly. For each test, it will run an /output/ instruction indicating
+how far the result of the test was from the expected value, where =0=
+means the test was successful. Non-zero outputs mean that a function is
+not working correctly; check the instructions that were run before the
+output instruction to see which one failed.
+
+Finally, the program will output a /diagnostic code/ and immediately
+halt. This final output isn't an error; an output followed immediately
+by a halt means the program finished. If all outputs were zero except
+the diagnostic code, the diagnostic program ran successfully.
+
+After providing =1= to the only input instruction and passing all the
+tests, /what diagnostic code does the program produce?/
+
+To begin, [[file:5/input][get your puzzle input]].