How to use the pegjs/lib/compiler/opcodes.CALL function in pegjs

parts.push(stack.push("peg$FAILED"));
            parts.push("if (peg$silentFails === 0) { peg$fail(" + c(bc[ip + 1]) + "); }");
            ip += 2;
            break;

          case op.LOAD_SAVED_POS: // LOAD_SAVED_POS p
            parts.push("peg$savedPos = " + stack.index(bc[ip + 1]) + ";");
            ip += 2;
            break;

          case op.UPDATE_SAVED_POS: // UPDATE_SAVED_POS
            parts.push("peg$savedPos = peg$currPos;");
            ip++;
            break;

          case op.CALL: // CALL f, n, pc, p1, p2, ..., pN
            compileCall();
            break;

          case op.RULE: // RULE r
            parts.push(stack.push("peg$parse" + ast.rules[bc[ip + 1]].name + "()"));
            ip += 2;
            break;

          case op.SILENT_FAILS_ON: // SILENT_FAILS_ON
            parts.push("peg$silentFails++;");
            ip++;
            break;

          case op.SILENT_FAILS_OFF: // SILENT_FAILS_OFF
            parts.push("peg$silentFails--;");
            ip++;

"            peg$fail(peg$consts[bc[ip + 1]] as ILiteralExpectation);",
      "          }",
      "          ip += 2;",
      "          break;",
      "",
      "        case " + op.LOAD_SAVED_POS + ":", // LOAD_SAVED_POS p
      "          peg$savedPos = stack[stack.length - 1 - bc[ip + 1]];",
      "          ip += 2;",
      "          break;",
      "",
      "        case " + op.UPDATE_SAVED_POS + ":", // UPDATE_SAVED_POS
      "          peg$savedPos = peg$currPos;",
      "          ip++;",
      "          break;",
      "",
      "        case " + op.CALL + ":", // CALL f, n, pc, p1, p2, ..., pN
      indent10(generateCall()),
      "",
      "        case " + op.RULE + ":", // RULE r
      "          stack.push(peg$parseRule(bc[ip + 1]));",
      "          ip += 2;",
      "          break;",
      "",
      "        case " + op.SILENT_FAILS_ON + ":", // SILENT_FAILS_ON
      "          peg$silentFails++;",
      "          ip++;",
      "          break;",
      "",
      "        case " + op.SILENT_FAILS_OFF + ":", // SILENT_FAILS_OFF
      "          peg$silentFails--;",
      "          ip++;",
      "          break;",

function buildCall(functionIndex, delta, env, sp) {
    let params = Object.keys(env).map(name => sp - env[name]);

    return [op.CALL, functionIndex, delta, params.length].concat(params);
  }