circuitpython/shared/runtime/pyexec.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * SPDX-FileCopyrightText: Copyright (c) 2013, 2014 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>

#include "py/compile.h"
#include "py/runtime.h"
#include "py/repl.h"
#include "py/gc.h"
#include "py/gc_long_lived.h"
#include "py/frozenmod.h"
#include "py/mphal.h"
#if MICROPY_HW_ENABLE_USB
#include "irq.h"
#include "usb.h"
#endif
#include "shared/readline/readline.h"
#include "shared/runtime/pyexec.h"
#include "genhdr/mpversion.h"

#if CIRCUITPY_ATEXIT
#include "shared-module/atexit/__init__.h"
#endif

pyexec_mode_kind_t pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
int pyexec_system_exit = 0;

#if MICROPY_REPL_INFO
STATIC bool repl_display_debugging_info = 0;
#endif

#define EXEC_FLAG_PRINT_EOF             (1 << 0)
#define EXEC_FLAG_ALLOW_DEBUGGING       (1 << 1)
#define EXEC_FLAG_IS_REPL               (1 << 2)
#define EXEC_FLAG_SOURCE_IS_RAW_CODE    (1 << 3)
#define EXEC_FLAG_SOURCE_IS_VSTR        (1 << 4)
#define EXEC_FLAG_SOURCE_IS_FILENAME    (1 << 5)
#define EXEC_FLAG_SOURCE_IS_READER      (1 << 6)
#define EXEC_FLAG_SOURCE_IS_ATEXIT      (1 << 7)

// parses, compiles and executes the code in the lexer
// frees the lexer before returning
// EXEC_FLAG_PRINT_EOF prints 2 EOF chars: 1 after normal output, 1 after exception output
// EXEC_FLAG_ALLOW_DEBUGGING allows debugging info to be printed after executing the code
// EXEC_FLAG_IS_REPL is used for REPL inputs (flag passed on to mp_compile)
STATIC int parse_compile_execute(const void *source, mp_parse_input_kind_t input_kind, mp_uint_t exec_flags, pyexec_result_t *result) {
    int ret = 0;
    #if MICROPY_REPL_INFO
    uint32_t start = 0;
    #endif

    #ifdef MICROPY_BOARD_BEFORE_PYTHON_EXEC
    MICROPY_BOARD_BEFORE_PYTHON_EXEC(input_kind, exec_flags);
    #endif

    // by default a SystemExit exception returns 0
    pyexec_system_exit = 0;

    nlr_buf_t nlr;
    nlr.ret_val = NULL;
    if (nlr_push(&nlr) == 0) {
        mp_obj_t module_fun;
        #if CIRCUITPY_ATEXIT
        if (!(exec_flags & EXEC_FLAG_SOURCE_IS_ATEXIT))
        #endif
        {
            #if MICROPY_MODULE_FROZEN_MPY
            if (exec_flags & EXEC_FLAG_SOURCE_IS_RAW_CODE) {
                // source is a raw_code object, create the function
                module_fun = mp_make_function_from_raw_code(source, MP_OBJ_NULL, MP_OBJ_NULL);
            } else
            #endif
            {
                #if MICROPY_ENABLE_COMPILER
                mp_lexer_t *lex;
                if (exec_flags & EXEC_FLAG_SOURCE_IS_VSTR) {
                    const vstr_t *vstr = source;
                    lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, vstr->buf, vstr->len, 0);
                } else if (exec_flags & EXEC_FLAG_SOURCE_IS_READER) {
                    lex = mp_lexer_new(MP_QSTR__lt_stdin_gt_, *(mp_reader_t *)source);
                } else if (exec_flags & EXEC_FLAG_SOURCE_IS_FILENAME) {
                    lex = mp_lexer_new_from_file(source);
                } else {
                    lex = (mp_lexer_t *)source;
                }
                // source is a lexer, parse and compile the script
                qstr source_name = lex->source_name;
                if (input_kind == MP_PARSE_FILE_INPUT) {
                    mp_store_global(MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
                }
                mp_parse_tree_t parse_tree = mp_parse(lex, input_kind);
                module_fun = mp_compile(&parse_tree, source_name, exec_flags & EXEC_FLAG_IS_REPL);
                // Clear the parse tree because it has a heap pointer we don't need anymore.
                *((uint32_t volatile *)&parse_tree.chunk) = 0;
                #else
                mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("script compilation not supported"));
                #endif
            }

            // If the code was loaded from a file it's likely to be running for a while so we'll long
            // live it and collect any garbage before running.
            if (input_kind == MP_PARSE_FILE_INPUT) {
                module_fun = make_obj_long_lived(module_fun, 6);
                gc_collect();
            }
        }

        // execute code
        mp_hal_set_interrupt_char(CHAR_CTRL_C); // allow ctrl-C to interrupt us
        #if MICROPY_REPL_INFO
        start = mp_hal_ticks_ms();
        #endif
        #if CIRCUITPY_ATEXIT
        if (exec_flags & EXEC_FLAG_SOURCE_IS_ATEXIT) {
            atexit_callback_t *callback = (atexit_callback_t *)source;
            mp_call_function_n_kw(callback->func, callback->n_pos, callback->n_kw, callback->args);
        } else
        #endif
        {
            mp_call_function_0(module_fun);
        }
        mp_hal_set_interrupt_char(-1); // disable interrupt
        mp_handle_pending(true); // handle any pending exceptions (and any callbacks)
        nlr_pop();
        ret = 0;
        if (exec_flags & EXEC_FLAG_PRINT_EOF) {
            mp_hal_stdout_tx_strn("\x04", 1);
        }
    } else {
        // uncaught exception
        mp_hal_set_interrupt_char(-1); // disable interrupt
        mp_handle_pending(false); // clear any pending exceptions (and run any callbacks)

        if (exec_flags & EXEC_FLAG_SOURCE_IS_READER) {
            const mp_reader_t *reader = source;
            reader->close(reader->data);
        }

        // print EOF after normal output
        if (exec_flags & EXEC_FLAG_PRINT_EOF) {
            mp_hal_stdout_tx_strn("\x04", 1);
        }

        // check for SystemExit
        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type((mp_obj_t)nlr.ret_val)), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) {
            // at the moment, the value of SystemExit is unused
            ret = pyexec_system_exit;
        #if CIRCUITPY_ALARM
        } else if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type((mp_obj_t)nlr.ret_val)), &mp_type_DeepSleepRequest)) {
            ret = PYEXEC_DEEP_SLEEP;
        #endif
        } else if ((mp_obj_t)nlr.ret_val == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
            ret = PYEXEC_RELOAD;
        } else {
            mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
            ret = PYEXEC_EXCEPTION;
        }

    }
    if (result != NULL) {
        result->return_code = ret;
        #if CIRCUITPY_ALARM
        // Don't set the exception object if we exited for deep sleep.
        if (ret != 0 && ret != PYEXEC_DEEP_SLEEP) {
        #else
        if (ret != 0) {
            #endif
            mp_obj_t return_value = (mp_obj_t)nlr.ret_val;
            result->exception = return_value;
            result->exception_line = -1;

            if (mp_obj_is_exception_instance(return_value)) {
                size_t n, *values;
                mp_obj_exception_get_traceback(return_value, &n, &values);
                if (values != NULL) {
                    result->exception_line = values[1];
                    result->exception_filename[sizeof(result->exception_filename) - 1] = '\0';
                    strncpy(result->exception_filename, qstr_str(values[0]), sizeof(result->exception_filename) - 1);
                }
            }
        }
    }

    #if MICROPY_REPL_INFO
    // display debugging info if wanted
    if ((exec_flags & EXEC_FLAG_ALLOW_DEBUGGING) && repl_display_debugging_info) {
        mp_uint_t ticks = mp_hal_ticks_ms() - start; // TODO implement a function that does this properly
        printf("took " UINT_FMT " ms\n", ticks);
        // qstr info
        {
            size_t n_pool, n_qstr, n_str_data_bytes, n_total_bytes;
            qstr_pool_info(&n_pool, &n_qstr, &n_str_data_bytes, &n_total_bytes);
            printf("qstr:\n  n_pool=" UINT_FMT "\n  n_qstr=" UINT_FMT "\n  "
                "n_str_data_bytes=" UINT_FMT "\n  n_total_bytes=" UINT_FMT "\n",
                (unsigned)n_pool, (unsigned)n_qstr, (unsigned)n_str_data_bytes, (unsigned)n_total_bytes);
        }

        #if MICROPY_ENABLE_GC
        // run collection and print GC info
        gc_collect();
        gc_dump_info();
        #endif
    }
    #endif

    if (exec_flags & EXEC_FLAG_PRINT_EOF) {
        mp_hal_stdout_tx_strn("\x04", 1);
    }

    #ifdef MICROPY_BOARD_AFTER_PYTHON_EXEC
    MICROPY_BOARD_AFTER_PYTHON_EXEC(input_kind, exec_flags, nlr.ret_val, &ret);
    #endif

    return ret;
}

#if MICROPY_ENABLE_COMPILER

// This can be configured by a port (and even configured to a function to be
// computed dynamically) to indicate the maximum number of bytes that can be
// held in the stdin buffer.
#ifndef MICROPY_REPL_STDIN_BUFFER_MAX
#define MICROPY_REPL_STDIN_BUFFER_MAX (256)
#endif

typedef struct _mp_reader_stdin_t {
    bool eof;
    uint16_t window_max;
    uint16_t window_remain;
} mp_reader_stdin_t;

STATIC mp_uint_t mp_reader_stdin_readbyte(void *data) {
    mp_reader_stdin_t *reader = (mp_reader_stdin_t *)data;

    if (reader->eof) {
        return MP_READER_EOF;
    }

    int c = mp_hal_stdin_rx_chr();

    if (c == CHAR_CTRL_C || c == CHAR_CTRL_D) {
        reader->eof = true;
        mp_hal_stdout_tx_strn("\x04", 1); // indicate end to host
        if (c == CHAR_CTRL_C) {
            #if MICROPY_KBD_EXCEPTION
            MP_STATE_VM(mp_kbd_exception).traceback->data = NULL;
            nlr_raise(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception)));
            #else
            mp_raise_type(&mp_type_KeyboardInterrupt);
            #endif
        } else {
            return MP_READER_EOF;
        }
    }

    if (--reader->window_remain == 0) {
        mp_hal_stdout_tx_strn("\x01", 1); // indicate window available to host
        reader->window_remain = reader->window_max;
    }

    return c;
}

STATIC void mp_reader_stdin_close(void *data) {
    mp_reader_stdin_t *reader = (mp_reader_stdin_t *)data;
    if (!reader->eof) {
        reader->eof = true;
        mp_hal_stdout_tx_strn("\x04", 1); // indicate end to host
        for (;;) {
            int c = mp_hal_stdin_rx_chr();
            if (c == CHAR_CTRL_C || c == CHAR_CTRL_D) {
                break;
            }
        }
    }
}

STATIC void mp_reader_new_stdin(mp_reader_t *reader, mp_reader_stdin_t *reader_stdin, uint16_t buf_max) {
    // Make flow-control window half the buffer size, and indicate to the host that 2x windows are
    // free (sending the window size implicitly indicates that a window is free, and then the 0x01
    // indicates that another window is free).
    size_t window = buf_max / 2;
    char reply[3] = { window & 0xff, window >> 8, 0x01 };
    mp_hal_stdout_tx_strn(reply, sizeof(reply));

    reader_stdin->eof = false;
    reader_stdin->window_max = window;
    reader_stdin->window_remain = window;
    reader->data = reader_stdin;
    reader->readbyte = mp_reader_stdin_readbyte;
    reader->close = mp_reader_stdin_close;
}

STATIC int do_reader_stdin(int c) {
    if (c != 'A') {
        // Unsupported command.
        mp_hal_stdout_tx_strn("R\x00", 2);
        return 0;
    }

    // Indicate reception of command.
    mp_hal_stdout_tx_strn("R\x01", 2);

    mp_reader_t reader;
    mp_reader_stdin_t reader_stdin;
    mp_reader_new_stdin(&reader, &reader_stdin, MICROPY_REPL_STDIN_BUFFER_MAX);
    int exec_flags = EXEC_FLAG_PRINT_EOF | EXEC_FLAG_SOURCE_IS_READER;
    return parse_compile_execute(&reader, MP_PARSE_FILE_INPUT, exec_flags, NULL);
}

#if MICROPY_REPL_EVENT_DRIVEN

typedef struct _repl_t {
    // This structure originally also held current REPL line,
    // but it was moved to MP_STATE_VM(repl_line) as containing
    // root pointer. Still keep structure in case more state
    // will be added later.
    // vstr_t line;
    bool cont_line;
    bool paste_mode;
} repl_t;

repl_t repl;

STATIC int pyexec_raw_repl_process_char(int c);
STATIC int pyexec_friendly_repl_process_char(int c);

void pyexec_event_repl_init(void) {
    MP_STATE_VM(repl_line) = vstr_new(32);
    repl.cont_line = false;
    repl.paste_mode = false;
    // no prompt before printing friendly REPL banner or entering raw REPL
    readline_init(MP_STATE_VM(repl_line), "");
    if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
        pyexec_raw_repl_process_char(CHAR_CTRL_A);
    } else {
        pyexec_friendly_repl_process_char(CHAR_CTRL_B);
    }
}

STATIC int pyexec_raw_repl_process_char(int c) {
    if (c == CHAR_CTRL_A) {
        // reset raw REPL
        if (vstr_len(MP_STATE_VM(repl_line)) == 2 && vstr_str(MP_STATE_VM(repl_line))[0] == CHAR_CTRL_E) {
            int ret = do_reader_stdin(vstr_str(MP_STATE_VM(repl_line))[1]);
            if (ret & PYEXEC_FORCED_EXIT) {
                return ret;
            }
            goto reset;
        }
        mp_hal_stdout_tx_str("raw REPL; CTRL-B to exit\r\n");
        goto reset;
    } else if (c == CHAR_CTRL_B) {
        // change to friendly REPL
        pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
        vstr_reset(MP_STATE_VM(repl_line));
        repl.cont_line = false;
        repl.paste_mode = false;
        pyexec_friendly_repl_process_char(CHAR_CTRL_B);
        return 0;
    } else if (c == CHAR_CTRL_C) {
        // clear line
        vstr_reset(MP_STATE_VM(repl_line));
        return 0;
    } else if (c == CHAR_CTRL_D) {
        // input finished
    } else {
        // let through any other raw 8-bit value
        vstr_add_byte(MP_STATE_VM(repl_line), c);
        return 0;
    }

    // indicate reception of command
    mp_hal_stdout_tx_str("OK");

    if (MP_STATE_VM(repl_line)->len == 0) {
        // exit for a soft reset
        mp_hal_stdout_tx_str("\r\n");
        vstr_clear(MP_STATE_VM(repl_line));
        return PYEXEC_FORCED_EXIT;
    }

    int ret = parse_compile_execute(MP_STATE_VM(repl_line), MP_PARSE_FILE_INPUT, EXEC_FLAG_PRINT_EOF | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
    if (ret & PYEXEC_FORCED_EXIT) {
        return ret;
    }

reset:
    vstr_reset(MP_STATE_VM(repl_line));
    mp_hal_stdout_tx_str(">");

    return 0;
}

STATIC int pyexec_friendly_repl_process_char(int c) {
    if (repl.paste_mode) {
        if (c == CHAR_CTRL_C) {
            // cancel everything
            mp_hal_stdout_tx_str("\r\n");
            goto input_restart;
        } else if (c == CHAR_CTRL_D) {
            // end of input
            mp_hal_stdout_tx_str("\r\n");
            int ret = parse_compile_execute(MP_STATE_VM(repl_line), MP_PARSE_FILE_INPUT, EXEC_FLAG_ALLOW_DEBUGGING | EXEC_FLAG_IS_REPL | EXEC_FLAG_SOURCE_IS_VSTR);
            if (ret & PYEXEC_FORCED_EXIT) {
                return ret;
            }
            goto input_restart;
        } else {
            // add char to buffer and echo
            vstr_add_byte(MP_STATE_VM(repl_line), c);
            if (c == '\r') {
                mp_hal_stdout_tx_str("\r\n=== ");
            } else {
                char buf[1] = {c};
                mp_hal_stdout_tx_strn(buf, 1);
            }
            return 0;
        }
    }

    int ret = readline_process_char(c);

    if (!repl.cont_line) {

        if (ret == CHAR_CTRL_A) {
            // change to raw REPL
            pyexec_mode_kind = PYEXEC_MODE_RAW_REPL;
            mp_hal_stdout_tx_str("\r\n");
            pyexec_raw_repl_process_char(CHAR_CTRL_A);
            return 0;
        } else if (ret == CHAR_CTRL_B) {
            // reset friendly REPL
            mp_hal_stdout_tx_str("\r\n");
            mp_hal_stdout_tx_str(MICROPY_FULL_VERSION_INFO);
            mp_hal_stdout_tx_str("\r\n");
            // mp_hal_stdout_tx_str("Type \"help()\" for more information.\r\n");
            goto input_restart;
        } else if (ret == CHAR_CTRL_C) {
            // break
            mp_hal_stdout_tx_str("\r\n");
            goto input_restart;
        } else if (ret == CHAR_CTRL_D) {
            // exit for a soft reset
            mp_hal_stdout_tx_str("\r\n");
            vstr_clear(MP_STATE_VM(repl_line));
            return PYEXEC_FORCED_EXIT;
        } else if (ret == CHAR_CTRL_E) {
            // paste mode
            mp_hal_stdout_tx_str("\r\npaste mode; Ctrl-C to cancel, Ctrl-D to finish\r\n=== ");
            vstr_reset(MP_STATE_VM(repl_line));
            repl.paste_mode = true;
            return 0;
        }

        if (ret < 0) {
            return 0;
        }

        if (!mp_repl_continue_with_input(vstr_null_terminated_str(MP_STATE_VM(repl_line)))) {
            goto exec;
        }

        vstr_add_byte(MP_STATE_VM(repl_line), '\n');
        repl.cont_line = true;
        readline_note_newline("... ");
        return 0;

    } else {

        if (ret == CHAR_CTRL_C) {
            // cancel everything
            mp_hal_stdout_tx_str("\r\n");
            repl.cont_line = false;
            goto input_restart;
        } else if (ret == CHAR_CTRL_D) {
            // stop entering compound statement
            goto exec;
        }

        if (ret < 0) {
            return 0;
        }

        if (mp_repl_continue_with_input(vstr_null_terminated_str(MP_STATE_VM(repl_line)))) {
            vstr_add_byte(MP_STATE_VM(repl_line), '\n');
            readline_note_newline("... ");
            return 0;
        }

    exec:;
        int ret = parse_compile_execute(MP_STATE_VM(repl_line), MP_PARSE_SINGLE_INPUT, EXEC_FLAG_ALLOW_DEBUGGING | EXEC_FLAG_IS_REPL | EXEC_FLAG_SOURCE_IS_VSTR);
        if (ret & PYEXEC_FORCED_EXIT) {
            return ret;
        }

    input_restart:
        vstr_reset(MP_STATE_VM(repl_line));
        repl.cont_line = false;
        repl.paste_mode = false;
        readline_init(MP_STATE_VM(repl_line), ">>> ");
        return 0;
    }
}

uint8_t pyexec_repl_active;
int pyexec_event_repl_process_char(int c) {
    pyexec_repl_active = 1;
    int res;
    if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
        res = pyexec_raw_repl_process_char(c);
    } else {
        res = pyexec_friendly_repl_process_char(c);
    }
    pyexec_repl_active = 0;
    return res;
}

#else // MICROPY_REPL_EVENT_DRIVEN

int pyexec_raw_repl(void) {
    vstr_t line;
    vstr_init(&line, 32);

raw_repl_reset:
    mp_hal_stdout_tx_str("raw REPL; CTRL-B to exit\r\n");

    for (;;) {
        vstr_reset(&line);
        mp_hal_stdout_tx_str(">");
        for (;;) {
            int c = mp_hal_stdin_rx_chr();
            if (c == CHAR_CTRL_A) {
                // reset raw REPL
                if (vstr_len(&line) == 2 && vstr_str(&line)[0] == CHAR_CTRL_E) {
                    int ret = do_reader_stdin(vstr_str(&line)[1]);
                    if (ret & PYEXEC_FORCED_EXIT) {
                        return ret;
                    }
                    vstr_reset(&line);
                    mp_hal_stdout_tx_str(">");
                    continue;
                }
                goto raw_repl_reset;
            } else if (c == CHAR_CTRL_B) {
                // change to friendly REPL
                mp_hal_stdout_tx_str("\r\n");
                vstr_clear(&line);
                pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
                return 0;
            } else if (c == CHAR_CTRL_C) {
                // clear line
                vstr_reset(&line);
            } else if (c == CHAR_CTRL_D) {
                // input finished
                break;
            } else {
                // let through any other raw 8-bit value
                vstr_add_byte(&line, c);
            }
        }

        // indicate reception of command
        mp_hal_stdout_tx_str("OK");

        if (line.len == 0) {
            // exit for a soft reset
            mp_hal_stdout_tx_str("\r\n");
            vstr_clear(&line);
            return PYEXEC_FORCED_EXIT;
        }

        int ret = parse_compile_execute(&line, MP_PARSE_FILE_INPUT, EXEC_FLAG_PRINT_EOF | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
        if (ret & PYEXEC_FORCED_EXIT) {
            return ret;
        }
    }
}

int pyexec_friendly_repl(void) {
    vstr_t line;
    vstr_init(&line, 32);

friendly_repl_reset:
    mp_hal_stdout_tx_str("\r\n");
    mp_hal_stdout_tx_str(MICROPY_FULL_VERSION_INFO);
    mp_hal_stdout_tx_str("\r\n");
    // mp_hal_stdout_tx_str("Type \"help()\" for more information.\r\n");

    // to test ctrl-C
    /*
    {
        uint32_t x[4] = {0x424242, 0xdeaddead, 0x242424, 0xdeadbeef};
        for (;;) {
            nlr_buf_t nlr;
            printf("pyexec_repl: %p\n", x);
            mp_hal_set_interrupt_char(CHAR_CTRL_C);
            if (nlr_push(&nlr) == 0) {
                for (;;) {
                }
            } else {
                printf("break\n");
            }
        }
    }
    */

    for (;;) {
    input_restart:

        #if MICROPY_HW_ENABLE_USB
        if (usb_vcp_is_enabled()) {
            // If the user gets to here and interrupts are disabled then
            // they'll never see the prompt, traceback etc. The USB REPL needs
            // interrupts to be enabled or no transfers occur. So we try to
            // do the user a favor and reenable interrupts.
            if (query_irq() == IRQ_STATE_DISABLED) {
                enable_irq(IRQ_STATE_ENABLED);
                mp_hal_stdout_tx_str("MPY: enabling IRQs\r\n");
            }
        }
        #endif

        // If the GC is locked at this point there is no way out except a reset,
        // so force the GC to be unlocked to help the user debug what went wrong.
        if (MP_STATE_THREAD(gc_lock_depth) != 0) {
            MP_STATE_THREAD(gc_lock_depth) = 0;
        }

        vstr_reset(&line);

        nlr_buf_t nlr;
        nlr.ret_val = NULL;
        int ret = 0;
        if (nlr_push(&nlr) == 0) {
            ret = readline(&line, ">>> ");
        } else {
            // Uncaught exception
            mp_handle_pending(false); // clear any pending exceptions (and run any callbacks)

            // Print exceptions but stay in the REPL. There are very few delayed
            // exceptions. The WatchDogTimer can raise one though.
            mp_hal_stdout_tx_str("\r\n");
            mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
        }
        mp_parse_input_kind_t parse_input_kind = MP_PARSE_SINGLE_INPUT;

        if (ret == CHAR_CTRL_A) {
            // change to raw REPL
            mp_hal_stdout_tx_str("\r\n");
            vstr_clear(&line);
            pyexec_mode_kind = PYEXEC_MODE_RAW_REPL;
            return 0;
        } else if (ret == CHAR_CTRL_B) {
            // reset friendly REPL
            mp_hal_stdout_tx_str("\r\n");
            goto friendly_repl_reset;
        } else if (ret == CHAR_CTRL_C) {
            // break
            mp_hal_stdout_tx_str("\r\n");
            continue;
        } else if (ret == CHAR_CTRL_D) {
            // exit for a soft reset
            mp_hal_stdout_tx_str("\r\n");
            vstr_clear(&line);
            return PYEXEC_FORCED_EXIT;
        } else if (ret == CHAR_CTRL_E) {
            // paste mode
            mp_hal_stdout_tx_str("\r\npaste mode; Ctrl-C to cancel, Ctrl-D to finish\r\n=== ");
            vstr_reset(&line);
            for (;;) {
                char c = mp_hal_stdin_rx_chr();
                if (c == CHAR_CTRL_C) {
                    // cancel everything
                    mp_hal_stdout_tx_str("\r\n");
                    goto input_restart;
                } else if (c == CHAR_CTRL_D) {
                    // end of input
                    mp_hal_stdout_tx_str("\r\n");
                    break;
                } else {
                    // add char to buffer and echo
                    vstr_add_byte(&line, c);
                    if (c == '\r') {
                        mp_hal_stdout_tx_str("\r\n=== ");
                    } else {
                        mp_hal_stdout_tx_strn(&c, 1);
                    }
                }
            }
            parse_input_kind = MP_PARSE_FILE_INPUT;
        } else if (vstr_len(&line) == 0) {
            continue;
        } else {
            // got a line with non-zero length, see if it needs continuing
            while (mp_repl_continue_with_input(vstr_null_terminated_str(&line))) {
                vstr_add_byte(&line, '\n');
                ret = readline(&line, "... ");
                if (ret == CHAR_CTRL_C) {
                    // cancel everything
                    mp_hal_stdout_tx_str("\r\n");
                    goto input_restart;
                } else if (ret == CHAR_CTRL_D) {
                    // stop entering compound statement
                    break;
                }
            }
        }

        ret = parse_compile_execute(&line, parse_input_kind, EXEC_FLAG_ALLOW_DEBUGGING | EXEC_FLAG_IS_REPL | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
        if (ret & PYEXEC_FORCED_EXIT) {
            return ret;
        }
    }
}

#endif // MICROPY_REPL_EVENT_DRIVEN
#endif // MICROPY_ENABLE_COMPILER

int pyexec_file(const char *filename, pyexec_result_t *result) {
    return parse_compile_execute(filename, MP_PARSE_FILE_INPUT, EXEC_FLAG_SOURCE_IS_FILENAME, result);
}

int pyexec_file_if_exists(const char *filename, pyexec_result_t *result) {
    #if MICROPY_MODULE_FROZEN
    if (mp_find_frozen_module(filename, NULL, NULL) == MP_IMPORT_STAT_FILE) {
        return pyexec_frozen_module(filename, result);
    }
    #endif
    if (mp_import_stat(filename) != MP_IMPORT_STAT_FILE) {
        return 1; // success (no file is the same as an empty file executing without fail)
    }
    return pyexec_file(filename, result);
}

#if MICROPY_MODULE_FROZEN
int pyexec_frozen_module(const char *name, pyexec_result_t *result) {
    void *frozen_data;
    int frozen_type;
    mp_find_frozen_module(name, &frozen_type, &frozen_data);

    switch (frozen_type) {
        #if MICROPY_MODULE_FROZEN_STR
        case MP_FROZEN_STR:
            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, 0, result);
        #endif

        #if MICROPY_MODULE_FROZEN_MPY
        case MP_FROZEN_MPY:
            return parse_compile_execute(frozen_data, MP_PARSE_FILE_INPUT, EXEC_FLAG_SOURCE_IS_RAW_CODE, result);
        #endif

        default:
            printf("could not find module '%s'\n", name);
            return false;
    }
}
#endif

#if CIRCUITPY_ATEXIT
int pyexec_exit_handler(const void *source, pyexec_result_t *result) {
    return parse_compile_execute(source, MP_PARSE_FILE_INPUT, EXEC_FLAG_SOURCE_IS_ATEXIT, result);
}
#endif

#if MICROPY_REPL_INFO
mp_obj_t pyb_set_repl_info(mp_obj_t o_value) {
    repl_display_debugging_info = mp_obj_get_int(o_value);
    return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(pyb_set_repl_info_obj, pyb_set_repl_info);
#endif