path: root/cpp/015jump

:(before "End Globals")
// Jump ops.
const int JUMP = 10;
:(before "End Primitive Recipe Numbers")
Recipe_number["jump"] = JUMP;
Next_recipe_number++;
:(before "End Primitive Recipe Implementations")
case JUMP: {
  trace("run") << "ingredient 0 is " << instructions[pc].ingredients[0].name;
  pc += to_int(instructions[pc].ingredients[0].name);
  break;
}

:(scenario "jump_can_skip_instructions")
recipe main [
  jump 1:offset
  1:integer <- copy 1:literal
]
+run: instruction 0
+run: ingredient 0 is 1
-run: instruction 1
-mem: storing in location 1

:(scenario "jump_backward")
recipe main [
  jump 1:offset  // 0 -+
  jump 1:offset  //    | 1 +-+
  jump -2:offset //  2 +-->+ |
]                //       3 \/
+run: instruction 0
+run: instruction 2
+run: instruction 1

:(before "End Globals")
const int JUMP_IF = 11;
:(before "End Primitive Recipe Numbers")
Recipe_number["jump-if"] = JUMP_IF;
Next_recipe_number++;
:(before "End Primitive Recipe Implementations")
case JUMP_IF: {
  vector<int> arg0 = read_memory(instructions[pc].ingredients[0]);
  assert(arg0.size() == 1);
  trace("run") << "ingredient 0 is " << arg0[0];
  if (!arg0[0]) {
    trace("run") << "jump-if fell through";
    break;
  }
  trace("run") << "ingredient 1 is " << instructions[pc].ingredients[1].name;
  pc += to_int(instructions[pc].ingredients[1].name);
  trace("run") << "jumping to instruction " << pc+1;
  break;
}

:(scenario "jump_if")
recipe main [
  jump-if 999:literal 1:offset
  1:integer <- copy 1:literal
]
+run: instruction 0
+run: ingredient 1 is 1
+run: jumping to instruction 2
-run: instruction 1
-mem: storing in location 1

:(scenario "jump_if_fallthrough")
recipe main [
  jump-if 0:literal 1:offset
  123:integer <- copy 1:literal
]
+run: instruction 0
+run: jump-if fell through
+run: instruction 1
+mem: storing in location 123

:(before "End Globals")
const int JUMP_UNLESS = 12;
:(before "End Primitive Recipe Numbers")
Recipe_number["jump-unless"] = JUMP_UNLESS;
Next_recipe_number++;
:(before "End Primitive Recipe Implementations")
case JUMP_UNLESS: {
  vector<int> arg0 = read_memory(instructions[pc].ingredients[0]);
  assert(arg0.size() == 1);
  trace("run") << "ingredient 0 is " << arg0[0];
  if (arg0[0]) {
    trace("run") << "jump-unless fell through";
    break;
  }
  trace("run") << "ingredient 1 is " << instructions[pc].ingredients[1].name;
  pc += to_int(instructions[pc].ingredients[1].name);
  trace("run") << "jumping to instruction " << pc+1;
  break;
}

:(scenario "jump_unless")
recipe main [
  jump-unless 0:literal 1:offset
  1:integer <- copy 1:literal
]
+run: instruction 0
+run: ingredient 1 is 1
+run: jumping to instruction 2
-run: instruction 1
-mem: storing in location 1

:(scenario "jump_unless_fallthrough")
recipe main [
  jump-unless 999:literal 1:offset
  123:integer <- copy 1:literal
]
+run: instruction 0
+run: ingredient 0 is 999
+run: jump-unless fell through
+run: instruction 1
+mem: storing in location 123