Initial data commit

Task/Execute-Brain-/UNIX-Shell/execute-brain-.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+# BrainF*** interpreter in bash
+if (( ! $# )); then
+  printf >&2 'Usage: %s program-file\n' "$0"
+  exit 1
+fi
+
+# load the program
+exec 3<"$1"
+program=()
+while IFS=  read -r line <&3; do
+  mapfile -t instr < <(tr -cd '[]<>.,+-' <<<"$line" | sed $'s/./&\\\n/g')
+  program+=("${instr[@]}")
+done
+exec 3<&-
+
+# parse loops
+loops=()
+matches=()
+for pc in "${!program[@]}"; do
+  instr=${program[pc]}
+  if [[ $instr == '[' ]]; then
+    loops=("$pc" "${loops[@]}")
+  elif [[ $instr == ']' ]]; then
+    matches[$pc]=${loops[0]}
+    matches[${loops[0]}]=$pc
+    loops=(${loops[@]:1})
+  fi
+done
+
+# execute program
+memory=(0)
+mp=0
+pc=0
+while (( pc < ${#program[@]} )); do
+  instr=${program[pc]}
+  (( pc+=1 ))
+  mem=${memory[mp]}
+  case "$instr" in
+    '[') if (( ! mem )); then (( pc=${matches[pc-1]}+1 )); fi;;
+    ']') if (( mem )); then (( pc=${matches[pc-1]}+1 )); fi;;
+    +) memory[mp]=$(( (mem + 1) % 256 ));;
+    -) memory[mp]=$(( (mem - 1) % 256 ));;
+    '>') (( mp+=1 )); if (( mp >= ${#memory[@]} )); then memory+=(0); fi;;
+    '<') (( mp-=1 )); if (( mp < 0 )); then memory=(0 "${memory[@]}"); mp=0; fi;;
+    .) printf %b $(printf '\\%03o' "$mem");;
+    ,) read -n1 c; memory[mp]=$(LC_CTYPE=C printf '%d' "'$c");;
+  esac
+done