circuitpython/py/objfun.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013, 2014 Damien P. George
 * Copyright (c) 2014 Paul Sokolovsky
 *
 * 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 <stdbool.h>
#include <string.h>
#include <assert.h>

#include "mpconfig.h"
#include "nlr.h"
#include "misc.h"
#include "qstr.h"
#include "obj.h"
#include "objtuple.h"
#include "objfun.h"
#include "runtime0.h"
#include "runtime.h"
#include "bc.h"
#include "stackctrl.h"

#if 0 // print debugging info
#define DEBUG_PRINT (1)
#else // don't print debugging info
#define DEBUG_printf(...) (void)0
#endif

// This binary_op method is used for all function types, and is also
// used to determine if an object is of generic function type.
mp_obj_t mp_obj_fun_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
    switch (op) {
        case MP_BINARY_OP_EQUAL:
            // These objects can be equal only if it's the same underlying structure,
            // we don't even need to check for 2nd arg type.
            return MP_BOOL(lhs_in == rhs_in);
    }
    return MP_OBJ_NULL; // op not supported
}

/******************************************************************************/
/* builtin functions                                                          */

// mp_obj_fun_builtin_t defined in obj.h

STATIC mp_obj_t fun_builtin_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    assert(MP_OBJ_IS_TYPE(self_in, &mp_type_fun_builtin));
    mp_obj_fun_builtin_t *self = self_in;

    // check number of arguments
    mp_arg_check_num(n_args, n_kw, self->n_args_min, self->n_args_max, self->is_kw);

    if (self->is_kw) {
        // function allows keywords

        // we create a map directly from the given args array
        mp_map_t kw_args;
        mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);

        return ((mp_fun_kw_t)self->fun)(n_args, args, &kw_args);

    } else if (self->n_args_min <= 3 && self->n_args_min == self->n_args_max) {
        // function requires a fixed number of arguments

        // dispatch function call
        switch (self->n_args_min) {
            case 0:
                return ((mp_fun_0_t)self->fun)();

            case 1:
                return ((mp_fun_1_t)self->fun)(args[0]);

            case 2:
                return ((mp_fun_2_t)self->fun)(args[0], args[1]);

            case 3:
                return ((mp_fun_3_t)self->fun)(args[0], args[1], args[2]);

            default:
                assert(0);
                return mp_const_none;
        }

    } else {
        // function takes a variable number of arguments, but no keywords

        return ((mp_fun_var_t)self->fun)(n_args, args);
    }
}

const mp_obj_type_t mp_type_fun_builtin = {
    { &mp_type_type },
    .name = MP_QSTR_function,
    .call = fun_builtin_call,
    .binary_op = mp_obj_fun_binary_op,
};

#if 0 // currently unused, and semi-obsolete
mp_obj_t mp_make_function_var(int n_args_min, mp_fun_var_t fun) {
    mp_obj_fun_builtin_t *o = m_new_obj(mp_obj_fun_builtin_t);
    o->base.type = &mp_type_fun_native;
    o->is_kw = false;
    o->n_args_min = n_args_min;
    o->n_args_max = MP_OBJ_FUN_ARGS_MAX;
    o->fun = fun;
    return o;
}

// min and max are inclusive
mp_obj_t mp_make_function_var_between(int n_args_min, int n_args_max, mp_fun_var_t fun) {
    mp_obj_fun_builtin_t *o = m_new_obj(mp_obj_fun_builtin_t);
    o->base.type = &mp_type_fun_native;
    o->is_kw = false;
    o->n_args_min = n_args_min;
    o->n_args_max = n_args_max;
    o->fun = fun;
    return o;
}
#endif

/******************************************************************************/
/* byte code functions                                                        */

const char *mp_obj_code_get_name(const byte *code_info) {
    qstr block_name = code_info[8] | (code_info[9] << 8) | (code_info[10] << 16) | (code_info[11] << 24);
    return qstr_str(block_name);
}

const char *mp_obj_fun_get_name(mp_const_obj_t fun_in) {
    const mp_obj_fun_bc_t *fun = fun_in;
    const byte *code_info = fun->bytecode;
    return mp_obj_code_get_name(code_info);
}

#if MICROPY_CPYTHON_COMPAT
STATIC void fun_bc_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
    mp_obj_fun_bc_t *o = o_in;
    print(env, "<function %s at 0x%x>", mp_obj_fun_get_name(o), o);
}
#endif

#if DEBUG_PRINT
STATIC void dump_args(const mp_obj_t *a, int sz) {
    DEBUG_printf("%p: ", a);
    for (int i = 0; i < sz; i++) {
        DEBUG_printf("%p ", a[i]);
    }
    DEBUG_printf("\n");
}
#else
#define dump_args(...) (void)0
#endif

STATIC NORETURN void fun_pos_args_mismatch(mp_obj_fun_bc_t *f, mp_uint_t expected, mp_uint_t given) {
#if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE
    // Generic message, to be reused for other argument issues
    nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
        "argument num/types mismatch"));
#elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NORMAL
    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
        "function takes %d positional arguments but %d were given", expected, given));
#elif MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_DETAILED
    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
        "%s() takes %d positional arguments but %d were given",
        mp_obj_fun_get_name(f), expected, given));
#endif
}

// With this macro you can tune the maximum number of function state bytes
// that will be allocated on the stack.  Any function that needs more
// than this will use the heap.
#define VM_MAX_STATE_ON_STACK (10 * sizeof(mp_uint_t))

// Set this to enable a simple stack overflow check.
#define VM_DETECT_STACK_OVERFLOW (0)

// code_state should have ->ip filled in (pointing past code info block),
// as well as ->n_state.
void mp_setup_code_state(mp_code_state *code_state, mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
    // This function is pretty complicated.  It's main aim is to be efficient in speed and RAM
    // usage for the common case of positional only args.
    mp_obj_fun_bc_t *self = self_in;
    mp_uint_t n_state = code_state->n_state;
    const byte *ip = code_state->ip;

    code_state->code_info = self->bytecode;
    code_state->sp = &code_state->state[0] - 1;
    code_state->exc_sp = (mp_exc_stack_t*)(code_state->state + n_state) - 1;

    // zero out the local stack to begin with
    memset(code_state->state, 0, n_state * sizeof(*code_state->state));

    const mp_obj_t *kwargs = args + n_args;

    // var_pos_kw_args points to the stack where the var-args tuple, and var-kw dict, should go (if they are needed)
    mp_obj_t *var_pos_kw_args = &code_state->state[n_state - 1 - self->n_pos_args - self->n_kwonly_args];

    // check positional arguments

    if (n_args > self->n_pos_args) {
        // given more than enough arguments
        if (!self->takes_var_args) {
            fun_pos_args_mismatch(self, self->n_pos_args, n_args);
        }
        // put extra arguments in varargs tuple
        *var_pos_kw_args-- = mp_obj_new_tuple(n_args - self->n_pos_args, args + self->n_pos_args);
        n_args = self->n_pos_args;
    } else {
        if (self->takes_var_args) {
            DEBUG_printf("passing empty tuple as *args\n");
            *var_pos_kw_args-- = mp_const_empty_tuple;
        }
        // Apply processing and check below only if we don't have kwargs,
        // otherwise, kw handling code below has own extensive checks.
        if (n_kw == 0 && !self->has_def_kw_args) {
            if (n_args >= self->n_pos_args - self->n_def_args) {
                // given enough arguments, but may need to use some default arguments
                for (mp_uint_t i = n_args; i < self->n_pos_args; i++) {
                    code_state->state[n_state - 1 - i] = self->extra_args[i - (self->n_pos_args - self->n_def_args)];
                }
            } else {
                fun_pos_args_mismatch(self, self->n_pos_args - self->n_def_args, n_args);
            }
        }
    }

    // copy positional args into state
    for (mp_uint_t i = 0; i < n_args; i++) {
        code_state->state[n_state - 1 - i] = args[i];
    }

    // check keyword arguments

    if (n_kw != 0 || self->has_def_kw_args) {
        DEBUG_printf("Initial args: ");
        dump_args(code_state->state + n_state - self->n_pos_args - self->n_kwonly_args, self->n_pos_args + self->n_kwonly_args);

        mp_obj_t dict = MP_OBJ_NULL;
        if (self->takes_kw_args) {
            dict = mp_obj_new_dict(n_kw); // TODO: better go conservative with 0?
            *var_pos_kw_args = dict;
        }

        for (mp_uint_t i = 0; i < n_kw; i++) {
            qstr arg_name = MP_OBJ_QSTR_VALUE(kwargs[2 * i]);
            for (mp_uint_t j = 0; j < self->n_pos_args + self->n_kwonly_args; j++) {
                if (arg_name == self->args[j]) {
                    if (code_state->state[n_state - 1 - j] != MP_OBJ_NULL) {
                        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                            "function got multiple values for argument '%s'", qstr_str(arg_name)));
                    }
                    code_state->state[n_state - 1 - j] = kwargs[2 * i + 1];
                    goto continue2;
                }
            }
            // Didn't find name match with positional args
            if (!self->takes_kw_args) {
                nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError, "function does not take keyword arguments"));
            }
            mp_obj_dict_store(dict, kwargs[2 * i], kwargs[2 * i + 1]);
continue2:;
        }

        DEBUG_printf("Args with kws flattened: ");
        dump_args(code_state->state + n_state - self->n_pos_args - self->n_kwonly_args, self->n_pos_args + self->n_kwonly_args);

        // fill in defaults for positional args
        mp_obj_t *d = &code_state->state[n_state - self->n_pos_args];
        mp_obj_t *s = &self->extra_args[self->n_def_args - 1];
        for (int i = self->n_def_args; i > 0; i--, d++, s--) {
            if (*d == MP_OBJ_NULL) {
                *d = *s;
            }
        }

        DEBUG_printf("Args after filling default positional: ");
        dump_args(code_state->state + n_state - self->n_pos_args - self->n_kwonly_args, self->n_pos_args + self->n_kwonly_args);

        // Check that all mandatory positional args are specified
        while (d < &code_state->state[n_state]) {
            if (*d++ == MP_OBJ_NULL) {
                nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                    "function missing required positional argument #%d", &code_state->state[n_state] - d));
            }
        }

        // Check that all mandatory keyword args are specified
        // Fill in default kw args if we have them
        for (mp_uint_t i = 0; i < self->n_kwonly_args; i++) {
            if (code_state->state[n_state - 1 - self->n_pos_args - i] == MP_OBJ_NULL) {
                mp_map_elem_t *elem = NULL;
                if (self->has_def_kw_args) {
                    elem = mp_map_lookup(&((mp_obj_dict_t*)self->extra_args[self->n_def_args])->map, MP_OBJ_NEW_QSTR(self->args[self->n_pos_args + i]), MP_MAP_LOOKUP);
                }
                if (elem != NULL) {
                    code_state->state[n_state - 1 - self->n_pos_args - i] = elem->value;
                } else {
                    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
                        "function missing required keyword argument '%s'", qstr_str(self->args[self->n_pos_args + i])));
                }
            }
        }

    } else {
        // no keyword arguments given
        if (self->n_kwonly_args != 0) {
            nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
                "function missing keyword-only argument"));
        }
        if (self->takes_kw_args) {
            *var_pos_kw_args = mp_obj_new_dict(0);
        }
    }

    // bytecode prelude: initialise closed over variables
    for (mp_uint_t n_local = *ip++; n_local > 0; n_local--) {
        mp_uint_t local_num = *ip++;
        code_state->state[n_state - 1 - local_num] = mp_obj_new_cell(code_state->state[n_state - 1 - local_num]);
    }

    // now that we skipped over the prelude, set the ip for the VM
    code_state->ip = ip;

    DEBUG_printf("Calling: n_pos_args=%d, n_kwonly_args=%d\n", self->n_pos_args, self->n_kwonly_args);
    dump_args(code_state->state + n_state - self->n_pos_args - self->n_kwonly_args, self->n_pos_args + self->n_kwonly_args);
    dump_args(code_state->state, n_state);
}


STATIC mp_obj_t fun_bc_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    MP_STACK_CHECK();

    DEBUG_printf("Input n_args: %d, n_kw: %d\n", n_args, n_kw);
    DEBUG_printf("Input pos args: ");
    dump_args(args, n_args);
    DEBUG_printf("Input kw args: ");
    dump_args(args + n_args, n_kw * 2);
    mp_obj_fun_bc_t *self = self_in;
    DEBUG_printf("Func n_def_args: %d\n", self->n_def_args);

    const byte *ip = self->bytecode;

    // get code info size, and skip line number table
    mp_uint_t code_info_size = ip[0] | (ip[1] << 8) | (ip[2] << 16) | (ip[3] << 24);
    ip += code_info_size;

    // bytecode prelude: state size and exception stack size; 16 bit uints
    mp_uint_t n_state = ip[0] | (ip[1] << 8);
    mp_uint_t n_exc_stack = ip[2] | (ip[3] << 8);
    ip += 4;

#if VM_DETECT_STACK_OVERFLOW
    n_state += 1;
#endif

    // allocate state for locals and stack
    mp_uint_t state_size = n_state * sizeof(mp_obj_t) + n_exc_stack * sizeof(mp_exc_stack_t);
    mp_code_state *code_state;
    if (state_size > VM_MAX_STATE_ON_STACK) {
        code_state = m_new_obj_var(mp_code_state, byte, state_size);
    } else {
        code_state = alloca(sizeof(mp_code_state) + state_size);
    }

    code_state->n_state = n_state;
    code_state->ip = ip;
    mp_setup_code_state(code_state, self_in, n_args, n_kw, args);

    // execute the byte code with the correct globals context
    mp_obj_dict_t *old_globals = mp_globals_get();
    mp_globals_set(self->globals);
    mp_vm_return_kind_t vm_return_kind = mp_execute_bytecode(code_state, MP_OBJ_NULL);
    mp_globals_set(old_globals);

#if VM_DETECT_STACK_OVERFLOW
    if (vm_return_kind == MP_VM_RETURN_NORMAL) {
        if (code_state->sp < code_state->state) {
            printf("VM stack underflow: " INT_FMT "\n", code_state->sp - code_state->state);
            assert(0);
        }
    }
    // We can't check the case when an exception is returned in state[n_state - 1]
    // and there are no arguments, because in this case our detection slot may have
    // been overwritten by the returned exception (which is allowed).
    if (!(vm_return_kind == MP_VM_RETURN_EXCEPTION && self->n_pos_args + self->n_kwonly_args == 0)) {
        // Just check to see that we have at least 1 null object left in the state.
        bool overflow = true;
        for (mp_uint_t i = 0; i < n_state - self->n_pos_args - self->n_kwonly_args; i++) {
            if (code_state->state[i] == MP_OBJ_NULL) {
                overflow = false;
                break;
            }
        }
        if (overflow) {
            printf("VM stack overflow state=%p n_state+1=" UINT_FMT "\n", code_state->state, n_state);
            assert(0);
        }
    }
#endif

    mp_obj_t result;
    switch (vm_return_kind) {
        case MP_VM_RETURN_NORMAL:
            // return value is in *sp
            result = *code_state->sp;
            break;

        case MP_VM_RETURN_EXCEPTION:
            // return value is in state[n_state - 1]
            result = code_state->state[n_state - 1];
            break;

        case MP_VM_RETURN_YIELD: // byte-code shouldn't yield
        default:
            assert(0);
            result = mp_const_none;
            vm_return_kind = MP_VM_RETURN_NORMAL;
            break;
    }

    // free the state if it was allocated on the heap
    if (state_size > VM_MAX_STATE_ON_STACK) {
        m_del_var(mp_code_state, byte, state_size, code_state);
    }

    if (vm_return_kind == MP_VM_RETURN_NORMAL) {
        return result;
    } else { // MP_VM_RETURN_EXCEPTION
        nlr_raise(result);
    }
}

const mp_obj_type_t mp_type_fun_bc = {
    { &mp_type_type },
    .name = MP_QSTR_function,
#if MICROPY_CPYTHON_COMPAT
    .print = fun_bc_print,
#endif
    .call = fun_bc_call,
    .binary_op = mp_obj_fun_binary_op,
};

mp_obj_t mp_obj_new_fun_bc(mp_uint_t scope_flags, qstr *args, mp_uint_t n_pos_args, mp_uint_t n_kwonly_args, mp_obj_t def_args_in, mp_obj_t def_kw_args, const byte *code) {
    mp_uint_t n_def_args = 0;
    mp_uint_t n_extra_args = 0;
    mp_obj_tuple_t *def_args = def_args_in;
    if (def_args != MP_OBJ_NULL) {
        assert(MP_OBJ_IS_TYPE(def_args, &mp_type_tuple));
        n_def_args = def_args->len;
        n_extra_args = def_args->len;
    }
    if (def_kw_args != MP_OBJ_NULL) {
        n_extra_args += 1;
    }
    mp_obj_fun_bc_t *o = m_new_obj_var(mp_obj_fun_bc_t, mp_obj_t, n_extra_args);
    o->base.type = &mp_type_fun_bc;
    o->globals = mp_globals_get();
    o->args = args;
    o->n_pos_args = n_pos_args;
    o->n_kwonly_args = n_kwonly_args;
    o->n_def_args = n_def_args;
    o->has_def_kw_args = def_kw_args != MP_OBJ_NULL;
    o->takes_var_args = (scope_flags & MP_SCOPE_FLAG_VARARGS) != 0;
    o->takes_kw_args = (scope_flags & MP_SCOPE_FLAG_VARKEYWORDS) != 0;
    o->bytecode = code;
    if (def_args != MP_OBJ_NULL) {
        memcpy(o->extra_args, def_args->items, n_def_args * sizeof(mp_obj_t));
    }
    if (def_kw_args != MP_OBJ_NULL) {
        o->extra_args[n_def_args] = def_kw_args;
    }
    return o;
}

/******************************************************************************/
/* native functions                                                           */

#if MICROPY_EMIT_NATIVE

typedef struct _mp_obj_fun_native_t {
    mp_obj_base_t base;
    mp_uint_t n_args;
    void *fun_data; // GC must be able to trace this pointer
    // TODO add mp_map_t *globals
} mp_obj_fun_native_t;

typedef mp_obj_t (*native_fun_0_t)();
typedef mp_obj_t (*native_fun_1_t)(mp_obj_t);
typedef mp_obj_t (*native_fun_2_t)(mp_obj_t, mp_obj_t);
typedef mp_obj_t (*native_fun_3_t)(mp_obj_t, mp_obj_t, mp_obj_t);

STATIC mp_obj_t fun_native_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    mp_obj_fun_native_t *self = self_in;

    mp_arg_check_num(n_args, n_kw, self->n_args, self->n_args, false);

    void *fun = MICROPY_MAKE_POINTER_CALLABLE(self->fun_data);

    switch (n_args) {
        case 0:
            return ((native_fun_0_t)fun)();

        case 1:
            return ((native_fun_1_t)fun)(args[0]);

        case 2:
            return ((native_fun_2_t)fun)(args[0], args[1]);

        case 3:
            return ((native_fun_3_t)fun)(args[0], args[1], args[2]);

        default:
            assert(0);
            return mp_const_none;
    }
}

STATIC const mp_obj_type_t mp_type_fun_native = {
    { &mp_type_type },
    .name = MP_QSTR_function,
    .call = fun_native_call,
    .binary_op = mp_obj_fun_binary_op,
};

mp_obj_t mp_obj_new_fun_native(mp_uint_t n_args, void *fun_data) {
    assert(0 <= n_args && n_args <= 3);
    mp_obj_fun_native_t *o = m_new_obj(mp_obj_fun_native_t);
    o->base.type = &mp_type_fun_native;
    o->n_args = n_args;
    o->fun_data = fun_data;
    return o;
}

#endif // MICROPY_EMIT_NATIVE

/******************************************************************************/
/* viper functions                                                            */

#if MICROPY_EMIT_NATIVE

typedef struct _mp_obj_fun_viper_t {
    mp_obj_base_t base;
    mp_uint_t n_args;
    void *fun_data; // GC must be able to trace this pointer
    mp_uint_t type_sig;
} mp_obj_fun_viper_t;

typedef mp_uint_t (*viper_fun_0_t)();
typedef mp_uint_t (*viper_fun_1_t)(mp_uint_t);
typedef mp_uint_t (*viper_fun_2_t)(mp_uint_t, mp_uint_t);
typedef mp_uint_t (*viper_fun_3_t)(mp_uint_t, mp_uint_t, mp_uint_t);

STATIC mp_obj_t fun_viper_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    mp_obj_fun_viper_t *self = self_in;

    mp_arg_check_num(n_args, n_kw, self->n_args, self->n_args, false);

    void *fun = MICROPY_MAKE_POINTER_CALLABLE(self->fun_data);

    mp_uint_t ret;
    if (n_args == 0) {
        ret = ((viper_fun_0_t)fun)();
    } else if (n_args == 1) {
        ret = ((viper_fun_1_t)fun)(mp_convert_obj_to_native(args[0], self->type_sig >> 2));
    } else if (n_args == 2) {
        ret = ((viper_fun_2_t)fun)(mp_convert_obj_to_native(args[0], self->type_sig >> 2), mp_convert_obj_to_native(args[1], self->type_sig >> 4));
    } else if (n_args == 3) {
        ret = ((viper_fun_3_t)fun)(mp_convert_obj_to_native(args[0], self->type_sig >> 2), mp_convert_obj_to_native(args[1], self->type_sig >> 4), mp_convert_obj_to_native(args[2], self->type_sig >> 6));
    } else {
        assert(0);
        ret = 0;
    }

    return mp_convert_native_to_obj(ret, self->type_sig);
}

STATIC const mp_obj_type_t mp_type_fun_viper = {
    { &mp_type_type },
    .name = MP_QSTR_function,
    .call = fun_viper_call,
    .binary_op = mp_obj_fun_binary_op,
};

mp_obj_t mp_obj_new_fun_viper(mp_uint_t n_args, void *fun_data, mp_uint_t type_sig) {
    mp_obj_fun_viper_t *o = m_new_obj(mp_obj_fun_viper_t);
    o->base.type = &mp_type_fun_viper;
    o->n_args = n_args;
    o->fun_data = fun_data;
    o->type_sig = type_sig;
    return o;
}

#endif // MICROPY_EMIT_NATIVE

/******************************************************************************/
/* inline assembler functions                                                 */

#if MICROPY_EMIT_INLINE_THUMB

typedef struct _mp_obj_fun_asm_t {
    mp_obj_base_t base;
    mp_uint_t n_args;
    void *fun_data; // GC must be able to trace this pointer
} mp_obj_fun_asm_t;

typedef mp_uint_t (*inline_asm_fun_0_t)();
typedef mp_uint_t (*inline_asm_fun_1_t)(mp_uint_t);
typedef mp_uint_t (*inline_asm_fun_2_t)(mp_uint_t, mp_uint_t);
typedef mp_uint_t (*inline_asm_fun_3_t)(mp_uint_t, mp_uint_t, mp_uint_t);

// convert a Micro Python object to a sensible value for inline asm
STATIC mp_uint_t convert_obj_for_inline_asm(mp_obj_t obj) {
    // TODO for byte_array, pass pointer to the array
    if (MP_OBJ_IS_SMALL_INT(obj)) {
        return MP_OBJ_SMALL_INT_VALUE(obj);
    } else if (obj == mp_const_none) {
        return 0;
    } else if (obj == mp_const_false) {
        return 0;
    } else if (obj == mp_const_true) {
        return 1;
    } else if (MP_OBJ_IS_STR(obj)) {
        // pointer to the string (it's probably constant though!)
        uint l;
        return (mp_uint_t)mp_obj_str_get_data(obj, &l);
    } else {
        mp_obj_type_t *type = mp_obj_get_type(obj);
        if (0) {
#if MICROPY_PY_BUILTINS_FLOAT
        } else if (type == &mp_type_float) {
            // convert float to int (could also pass in float registers)
            return (mp_int_t)mp_obj_float_get(obj);
#endif
        } else if (type == &mp_type_tuple) {
            // pointer to start of tuple (could pass length, but then could use len(x) for that)
            uint len;
            mp_obj_t *items;
            mp_obj_tuple_get(obj, &len, &items);
            return (mp_uint_t)items;
        } else if (type == &mp_type_list) {
            // pointer to start of list (could pass length, but then could use len(x) for that)
            uint len;
            mp_obj_t *items;
            mp_obj_list_get(obj, &len, &items);
            return (mp_uint_t)items;
        } else {
            mp_buffer_info_t bufinfo;
            if (mp_get_buffer(obj, &bufinfo, MP_BUFFER_WRITE)) {
                // supports the buffer protocol, return a pointer to the data
                return (mp_uint_t)bufinfo.buf;
            } else {
                // just pass along a pointer to the object
                return (mp_uint_t)obj;
            }
        }
    }
}

// convert a return value from inline asm to a sensible Micro Python object
STATIC mp_obj_t convert_val_from_inline_asm(mp_uint_t val) {
    return MP_OBJ_NEW_SMALL_INT(val);
}

STATIC mp_obj_t fun_asm_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    mp_obj_fun_asm_t *self = self_in;

    mp_arg_check_num(n_args, n_kw, self->n_args, self->n_args, false);

    void *fun = MICROPY_MAKE_POINTER_CALLABLE(self->fun_data);

    mp_uint_t ret;
    if (n_args == 0) {
        ret = ((inline_asm_fun_0_t)fun)();
    } else if (n_args == 1) {
        ret = ((inline_asm_fun_1_t)fun)(convert_obj_for_inline_asm(args[0]));
    } else if (n_args == 2) {
        ret = ((inline_asm_fun_2_t)fun)(convert_obj_for_inline_asm(args[0]), convert_obj_for_inline_asm(args[1]));
    } else if (n_args == 3) {
        ret = ((inline_asm_fun_3_t)fun)(convert_obj_for_inline_asm(args[0]), convert_obj_for_inline_asm(args[1]), convert_obj_for_inline_asm(args[2]));
    } else {
        assert(0);
        ret = 0;
    }

    return convert_val_from_inline_asm(ret);
}

STATIC const mp_obj_type_t mp_type_fun_asm = {
    { &mp_type_type },
    .name = MP_QSTR_function,
    .call = fun_asm_call,
    .binary_op = mp_obj_fun_binary_op,
};

mp_obj_t mp_obj_new_fun_asm(mp_uint_t n_args, void *fun_data) {
    mp_obj_fun_asm_t *o = m_new_obj(mp_obj_fun_asm_t);
    o->base.type = &mp_type_fun_asm;
    o->n_args = n_args;
    o->fun_data = fun_data;
    return o;
}

#endif // MICROPY_EMIT_INLINE_THUMB