AOC2019day5part2

5-2.sh

#!/bin/bash

set -eu

IFS=, read -r -a ram < "$1"

getval() {
  case $1 in
    0) echo "${ram[$2]}" ;;
    1) echo "$2" ;;
  esac
}

jmpt() {
  addrmode=$1
  arg=$(getval "${addrmode:0:1}" "$2")
  dest=$(getval "${addrmode:1:1}" "$3")
  if [ "$arg" -ne 0 ]; then
    pc=$dest
  else
    pc=$((pc+2))
  fi
}

jmpf() {
  addrmode=$1
  arg=$(getval "${addrmode:0:1}" "$2")
  dest=$(getval "${addrmode:1:1}" "$3")
  if [ "$arg" -eq 0 ]; then
    pc=$dest
  else
    pc=$((pc+2))
  fi
}

add() {
  addrmode=$1
  src1=$(getval "${addrmode:0:1}" "$2")
  src2=$(getval "${addrmode:1:1}" "$3")
  dest=$4
  ram[$dest]=$((src1 + src2))
  pc=$((pc+3))
}

mul() {
  addrmode=$1
  src1=$(getval "${addrmode:0:1}" "$2")
  src2=$(getval "${addrmode:1:1}" "$3")
  dest=$4
  ram[$dest]=$((src1 * src2))
  pc=$((pc+3))
}

cmpl() {
  addrmode=$1
  src1=$(getval "${addrmode:0:1}" "$2")
  src2=$(getval "${addrmode:1:1}" "$3")
  dest=$4
  if [ "$src1" -lt "$src2" ]; then
    ans=1
  else
    ans=0
  fi
  ram[$dest]=$ans
  pc=$((pc+3))
}

cmpe() {
  addrmode=$1
  src1=$(getval "${addrmode:0:1}" "$2")
  src2=$(getval "${addrmode:1:1}" "$3")
  dest=$4
  if [ "$src1" -eq "$src2" ]; then
    ans=1
  else
    ans=0
  fi
  ram[$dest]=$ans
  pc=$((pc+3))
}

inb() {
  addrmode=$1
  dest=$2
  input=5
  ram[$dest]=$input
  pc=$((pc+1))
}

outb() {
  addrmode=$1
  src=$(getval "${addrmode:0:1}" "$2")
  echo $src
  pc=$((pc+1))
}

pc=0
while true; do
  opcode=$(printf %04d "${ram[$pc]}")
  addrmode=$(rev <<<"${opcode%??}")
  op=${opcode: -2}
  pc=$((pc+1))
  case $op in
    01) add  "$addrmode" "${ram[@]:$pc:3}" ;;
    02) mul  "$addrmode" "${ram[@]:$pc:3}" ;;
    03) inb  "$addrmode" "${ram[@]:$pc:1}" ;;
    04) outb "$addrmode" "${ram[@]:$pc:1}" ;;
    05) jmpt "$addrmode" "${ram[@]:$pc:2}" ;;
    06) jmpf "$addrmode" "${ram[@]:$pc:2}" ;;
    07) cmpl "$addrmode" "${ram[@]:$pc:3}" ;;
    08) cmpe "$addrmode" "${ram[@]:$pc:3}" ;;
    99) break ;;
    *)
      echo "Unknown opcode $opcode at $pc" >&2
      exit 1
    ;;
  esac
done