extmod/moduselect.c - lite/micropython - Linaro Git Browser

 /*
  * This file is part of the Micro Python project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
  * Copyright (c) 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 "py/mpconfig.h"
 #if MICROPY_PY_USELECT

 #include <stdio.h>

 #include "py/runtime.h"
 #include "py/obj.h"
 #include "py/objlist.h"
 #include "py/stream.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"

 // Flags for poll()
 #define FLAG_ONESHOT (1)

 /// \module select - Provides select function to wait for events on a stream
 ///
 /// This module provides the select function.

 typedef struct _poll_obj_t {
     mp_obj_t obj;
     mp_uint_t (*ioctl)(mp_obj_t obj, mp_uint_t request, mp_uint_t arg, int *errcode);
     mp_uint_t flags;
     mp_uint_t flags_ret;
 } poll_obj_t;

 STATIC void poll_map_add(mp_map_t *poll_map, const mp_obj_t *obj, mp_uint_t obj_len, mp_uint_t flags, bool or_flags) {
     for (mp_uint_t i = 0; i < obj_len; i++) {
         mp_map_elem_t *elem = mp_map_lookup(poll_map, mp_obj_id(obj[i]), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
         if (elem->value == NULL) {
             // object not found; get its ioctl and add it to the poll list
             const mp_stream_p_t *stream_p = mp_get_stream_raise(obj[i], MP_STREAM_OP_IOCTL);
             poll_obj_t *poll_obj = m_new_obj(poll_obj_t);
             poll_obj->obj = obj[i];
             poll_obj->ioctl = stream_p->ioctl;
             poll_obj->flags = flags;
             poll_obj->flags_ret = 0;
             elem->value = poll_obj;
         } else {
             // object exists; update its flags
             if (or_flags) {
                 ((poll_obj_t*)elem->value)->flags |= flags;
             } else {
                 ((poll_obj_t*)elem->value)->flags = flags;
             }
         }
     }
 }

 // poll each object in the map
 STATIC mp_uint_t poll_map_poll(mp_map_t *poll_map, mp_uint_t *rwx_num) {
     mp_uint_t n_ready = 0;
     for (mp_uint_t i = 0; i < poll_map->alloc; ++i) {
         if (!MP_MAP_SLOT_IS_FILLED(poll_map, i)) {
             continue;
         }

         poll_obj_t *poll_obj = (poll_obj_t*)poll_map->table[i].value;
         int errcode;
         mp_int_t ret = poll_obj->ioctl(poll_obj->obj, MP_STREAM_POLL, poll_obj->flags, &errcode);
         poll_obj->flags_ret = ret;

         if (ret == -1) {
             // error doing ioctl
             mp_raise_OSError(errcode);
         }

         if (ret != 0) {
             // object is ready
             n_ready += 1;
             if (rwx_num != NULL) {
                 if (ret & MP_STREAM_POLL_RD) {
                     rwx_num[0] += 1;
                 }
                 if (ret & MP_STREAM_POLL_WR) {
                     rwx_num[1] += 1;
                 }
                 if ((ret & ~(MP_STREAM_POLL_RD | MP_STREAM_POLL_WR)) != 0) {
                     rwx_num[2] += 1;
                 }
             }
         }
     }
     return n_ready;
 }

 /// \function select(rlist, wlist, xlist[, timeout])
 STATIC mp_obj_t select_select(uint n_args, const mp_obj_t *args) {
     // get array data from tuple/list arguments
     size_t rwx_len[3];
     mp_obj_t *r_array, *w_array, *x_array;
     mp_obj_get_array(args[0], &rwx_len[0], &r_array);
     mp_obj_get_array(args[1], &rwx_len[1], &w_array);
     mp_obj_get_array(args[2], &rwx_len[2], &x_array);

     // get timeout
     mp_uint_t timeout = -1;
     if (n_args == 4) {
         if (args[3] != mp_const_none) {
             #if MICROPY_PY_BUILTINS_FLOAT
             float timeout_f = mp_obj_get_float(args[3]);
             if (timeout_f >= 0) {
                 timeout = (mp_uint_t)(timeout_f * 1000);
             }
             #else
             timeout = mp_obj_get_int(args[3]) * 1000;
             #endif
         }
     }

     // merge separate lists and get the ioctl function for each object
     mp_map_t poll_map;
     mp_map_init(&poll_map, rwx_len[0] + rwx_len[1] + rwx_len[2]);
     poll_map_add(&poll_map, r_array, rwx_len[0], MP_STREAM_POLL_RD, true);
     poll_map_add(&poll_map, w_array, rwx_len[1], MP_STREAM_POLL_WR, true);
     poll_map_add(&poll_map, x_array, rwx_len[2], MP_STREAM_POLL_ERR | MP_STREAM_POLL_HUP, true);

     mp_uint_t start_tick = mp_hal_ticks_ms();
     rwx_len[0] = rwx_len[1] = rwx_len[2] = 0;
     for (;;) {
         // poll the objects
         mp_uint_t n_ready = poll_map_poll(&poll_map, rwx_len);

         if (n_ready > 0 || (timeout != -1 && mp_hal_ticks_ms() - start_tick >= timeout)) {
             // one or more objects are ready, or we had a timeout
             mp_obj_t list_array[3];
             list_array[0] = mp_obj_new_list(rwx_len[0], NULL);
             list_array[1] = mp_obj_new_list(rwx_len[1], NULL);
             list_array[2] = mp_obj_new_list(rwx_len[2], NULL);
             rwx_len[0] = rwx_len[1] = rwx_len[2] = 0;
             for (mp_uint_t i = 0; i < poll_map.alloc; ++i) {
                 if (!MP_MAP_SLOT_IS_FILLED(&poll_map, i)) {
                     continue;
                 }
                 poll_obj_t *poll_obj = (poll_obj_t*)poll_map.table[i].value;
                 if (poll_obj->flags_ret & MP_STREAM_POLL_RD) {
                     ((mp_obj_list_t*)list_array[0])->items[rwx_len[0]++] = poll_obj->obj;
                 }
                 if (poll_obj->flags_ret & MP_STREAM_POLL_WR) {
                     ((mp_obj_list_t*)list_array[1])->items[rwx_len[1]++] = poll_obj->obj;
                 }
                 if ((poll_obj->flags_ret & ~(MP_STREAM_POLL_RD | MP_STREAM_POLL_WR)) != 0) {
                     ((mp_obj_list_t*)list_array[2])->items[rwx_len[2]++] = poll_obj->obj;
                 }
             }
             mp_map_deinit(&poll_map);
             return mp_obj_new_tuple(3, list_array);
         }
         MICROPY_EVENT_POLL_HOOK
     }
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_select_select_obj, 3, 4, select_select);

 /// \class Poll - poll class

 typedef struct _mp_obj_poll_t {
     mp_obj_base_t base;
     mp_map_t poll_map;
     short iter_cnt;
     short iter_idx;
     int flags;
     // callee-owned tuple
     mp_obj_t ret_tuple;
 } mp_obj_poll_t;

 /// \method register(obj[, eventmask])
 STATIC mp_obj_t poll_register(uint n_args, const mp_obj_t *args) {
     mp_obj_poll_t *self = args[0];
     mp_uint_t flags;
     if (n_args == 3) {
         flags = mp_obj_get_int(args[2]);
     } else {
         flags = MP_STREAM_POLL_RD | MP_STREAM_POLL_WR;
     }
     poll_map_add(&self->poll_map, &args[1], 1, flags, false);
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_register_obj, 2, 3, poll_register);

 /// \method unregister(obj)
 STATIC mp_obj_t poll_unregister(mp_obj_t self_in, mp_obj_t obj_in) {
     mp_obj_poll_t *self = self_in;
     mp_map_lookup(&self->poll_map, mp_obj_id(obj_in), MP_MAP_LOOKUP_REMOVE_IF_FOUND);
     // TODO raise KeyError if obj didn't exist in map
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_2(poll_unregister_obj, poll_unregister);

 /// \method modify(obj, eventmask)
 STATIC mp_obj_t poll_modify(mp_obj_t self_in, mp_obj_t obj_in, mp_obj_t eventmask_in) {
     mp_obj_poll_t *self = self_in;
     mp_map_elem_t *elem = mp_map_lookup(&self->poll_map, mp_obj_id(obj_in), MP_MAP_LOOKUP);
     if (elem == NULL) {
         mp_raise_OSError(MP_ENOENT);
     }
     ((poll_obj_t*)elem->value)->flags = mp_obj_get_int(eventmask_in);
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_3(poll_modify_obj, poll_modify);

 STATIC mp_uint_t poll_poll_internal(uint n_args, const mp_obj_t *args) {
     mp_obj_poll_t *self = args[0];

     // work out timeout (its given already in ms)
     mp_uint_t timeout = -1;
     int flags = 0;
     if (n_args >= 2) {
         if (args[1] != mp_const_none) {
             mp_int_t timeout_i = mp_obj_get_int(args[1]);
             if (timeout_i >= 0) {
                 timeout = timeout_i;
             }
         }
         if (n_args >= 3) {
             flags = mp_obj_get_int(args[2]);
         }
     }

     self->flags = flags;

     mp_uint_t start_tick = mp_hal_ticks_ms();
     mp_uint_t n_ready;
     for (;;) {
         // poll the objects
         n_ready = poll_map_poll(&self->poll_map, NULL);
         if (n_ready > 0 || (timeout != -1 && mp_hal_ticks_ms() - start_tick >= timeout)) {
             break;
         }
         MICROPY_EVENT_POLL_HOOK
     }

     return n_ready;
 }

 STATIC mp_obj_t poll_poll(uint n_args, const mp_obj_t *args) {
     mp_obj_poll_t *self = args[0];
     mp_uint_t n_ready = poll_poll_internal(n_args, args);

     // one or more objects are ready, or we had a timeout
     mp_obj_list_t *ret_list = mp_obj_new_list(n_ready, NULL);
     n_ready = 0;
     for (mp_uint_t i = 0; i < self->poll_map.alloc; ++i) {
         if (!MP_MAP_SLOT_IS_FILLED(&self->poll_map, i)) {
             continue;
         }
         poll_obj_t *poll_obj = (poll_obj_t*)self->poll_map.table[i].value;
         if (poll_obj->flags_ret != 0) {
             mp_obj_t tuple[2] = {poll_obj->obj, MP_OBJ_NEW_SMALL_INT(poll_obj->flags_ret)};
             ret_list->items[n_ready++] = mp_obj_new_tuple(2, tuple);
             if (self->flags & FLAG_ONESHOT) {
                 // Don't poll next time, until new event flags will be set explicitly
                 poll_obj->flags = 0;
             }
         }
     }
     return ret_list;
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_poll_obj, 1, 3, poll_poll);

 STATIC mp_obj_t poll_ipoll(size_t n_args, const mp_obj_t *args) {
     mp_obj_poll_t *self = MP_OBJ_TO_PTR(args[0]);

     if (self->ret_tuple == MP_OBJ_NULL) {
         self->ret_tuple = mp_obj_new_tuple(2, NULL);
     }

     int n_ready = poll_poll_internal(n_args, args);
     self->iter_cnt = n_ready;
     self->iter_idx = 0;

     return args[0];
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_ipoll_obj, 1, 3, poll_ipoll);

 STATIC mp_obj_t poll_iternext(mp_obj_t self_in) {
     mp_obj_poll_t *self = MP_OBJ_TO_PTR(self_in);

     if (self->iter_cnt == 0) {
         return MP_OBJ_STOP_ITERATION;
     }

     self->iter_cnt--;

     for (mp_uint_t i = self->iter_idx; i < self->poll_map.alloc; ++i) {
         self->iter_idx++;
         if (!MP_MAP_SLOT_IS_FILLED(&self->poll_map, i)) {
             continue;
         }
         poll_obj_t *poll_obj = (poll_obj_t*)self->poll_map.table[i].value;
         if (poll_obj->flags_ret != 0) {
             mp_obj_tuple_t *t = MP_OBJ_TO_PTR(self->ret_tuple);
             t->items[0] = poll_obj->obj;
             t->items[1] = MP_OBJ_NEW_SMALL_INT(poll_obj->flags_ret);
             if (self->flags & FLAG_ONESHOT) {
                 // Don't poll next time, until new event flags will be set explicitly
                 poll_obj->flags = 0;
             }
             return MP_OBJ_FROM_PTR(t);
         }
     }

     assert(!"inconsistent number of poll active entries");
     self->iter_cnt = 0;
     return MP_OBJ_STOP_ITERATION;
 }

 STATIC const mp_rom_map_elem_t poll_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_register), MP_ROM_PTR(&poll_register_obj) },
     { MP_ROM_QSTR(MP_QSTR_unregister), MP_ROM_PTR(&poll_unregister_obj) },
     { MP_ROM_QSTR(MP_QSTR_modify), MP_ROM_PTR(&poll_modify_obj) },
     { MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&poll_poll_obj) },
     { MP_ROM_QSTR(MP_QSTR_ipoll), MP_ROM_PTR(&poll_ipoll_obj) },
 };
 STATIC MP_DEFINE_CONST_DICT(poll_locals_dict, poll_locals_dict_table);

 STATIC const mp_obj_type_t mp_type_poll = {
     { &mp_type_type },
     .name = MP_QSTR_poll,
     .getiter = mp_identity_getiter,
     .iternext = poll_iternext,
     .locals_dict = (void*)&poll_locals_dict,
 };

 /// \function poll()
 STATIC mp_obj_t select_poll(void) {
     mp_obj_poll_t *poll = m_new_obj(mp_obj_poll_t);
     poll->base.type = &mp_type_poll;
     mp_map_init(&poll->poll_map, 0);
     poll->iter_cnt = 0;
     poll->ret_tuple = MP_OBJ_NULL;
     return poll;
 }
 MP_DEFINE_CONST_FUN_OBJ_0(mp_select_poll_obj, select_poll);

 STATIC const mp_rom_map_elem_t mp_module_select_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uselect) },
     { MP_ROM_QSTR(MP_QSTR_select), MP_ROM_PTR(&mp_select_select_obj) },
     { MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&mp_select_poll_obj) },
     { MP_ROM_QSTR(MP_QSTR_POLLIN), MP_ROM_INT(MP_STREAM_POLL_RD) },
     { MP_ROM_QSTR(MP_QSTR_POLLOUT), MP_ROM_INT(MP_STREAM_POLL_WR) },
     { MP_ROM_QSTR(MP_QSTR_POLLERR), MP_ROM_INT(MP_STREAM_POLL_ERR) },
     { MP_ROM_QSTR(MP_QSTR_POLLHUP), MP_ROM_INT(MP_STREAM_POLL_HUP) },
 };

 STATIC MP_DEFINE_CONST_DICT(mp_module_select_globals, mp_module_select_globals_table);

 const mp_obj_module_t mp_module_uselect = {
     .base = { &mp_type_module },
     .globals = (mp_obj_dict_t*)&mp_module_select_globals,
 };

 #endif // MICROPY_PY_USELECT
	/*
	* This file is part of the Micro Python project, http://micropython.org/
	*
	* The MIT License (MIT)
	*
	* Copyright (c) 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 "py/mpconfig.h"
	#if MICROPY_PY_USELECT

	#include <stdio.h>

	#include "py/runtime.h"
	#include "py/obj.h"
	#include "py/objlist.h"
	#include "py/stream.h"
	#include "py/mperrno.h"
	#include "py/mphal.h"

	// Flags for poll()
	#define FLAG_ONESHOT (1)

	/// \module select - Provides select function to wait for events on a stream
	///
	/// This module provides the select function.

	typedef struct _poll_obj_t {
	mp_obj_t obj;
	mp_uint_t (ioctl)(mp_obj_t obj, mp_uint_t request, mp_uint_t arg, int errcode);
	mp_uint_t flags;
	mp_uint_t flags_ret;
	} poll_obj_t;

	STATIC void poll_map_add(mp_map_t poll_map, const mp_obj_t obj, mp_uint_t obj_len, mp_uint_t flags, bool or_flags) {
	for (mp_uint_t i = 0; i < obj_len; i++) {
	mp_map_elem_t *elem = mp_map_lookup(poll_map, mp_obj_id(obj[i]), MP_MAP_LOOKUP_ADD_IF_NOT_FOUND);
	if (elem->value == NULL) {
	// object not found; get its ioctl and add it to the poll list
	const mp_stream_p_t *stream_p = mp_get_stream_raise(obj[i], MP_STREAM_OP_IOCTL);
	poll_obj_t *poll_obj = m_new_obj(poll_obj_t);
	poll_obj->obj = obj[i];
	poll_obj->ioctl = stream_p->ioctl;
	poll_obj->flags = flags;
	poll_obj->flags_ret = 0;
	elem->value = poll_obj;
	} else {
	// object exists; update its flags
	if (or_flags) {
	((poll_obj_t*)elem->value)->flags \|= flags;
	} else {
	((poll_obj_t*)elem->value)->flags = flags;
	}
	}
	}
	}

	// poll each object in the map
	STATIC mp_uint_t poll_map_poll(mp_map_t poll_map, mp_uint_t rwx_num) {
	mp_uint_t n_ready = 0;
	for (mp_uint_t i = 0; i < poll_map->alloc; ++i) {
	if (!MP_MAP_SLOT_IS_FILLED(poll_map, i)) {
	continue;
	}

	poll_obj_t poll_obj = (poll_obj_t)poll_map->table[i].value;
	int errcode;
	mp_int_t ret = poll_obj->ioctl(poll_obj->obj, MP_STREAM_POLL, poll_obj->flags, &errcode);
	poll_obj->flags_ret = ret;

	if (ret == -1) {
	// error doing ioctl
	mp_raise_OSError(errcode);
	}

	if (ret != 0) {
	// object is ready
	n_ready += 1;
	if (rwx_num != NULL) {
	if (ret & MP_STREAM_POLL_RD) {
	rwx_num[0] += 1;
	}
	if (ret & MP_STREAM_POLL_WR) {
	rwx_num[1] += 1;
	}
	if ((ret & ~(MP_STREAM_POLL_RD \| MP_STREAM_POLL_WR)) != 0) {
	rwx_num[2] += 1;
	}
	}
	}
	}
	return n_ready;
	}

	/// \function select(rlist, wlist, xlist[, timeout])
	STATIC mp_obj_t select_select(uint n_args, const mp_obj_t *args) {
	// get array data from tuple/list arguments
	size_t rwx_len[3];
	mp_obj_t r_array, w_array, *x_array;
	mp_obj_get_array(args[0], &rwx_len[0], &r_array);
	mp_obj_get_array(args[1], &rwx_len[1], &w_array);
	mp_obj_get_array(args[2], &rwx_len[2], &x_array);

	// get timeout
	mp_uint_t timeout = -1;
	if (n_args == 4) {
	if (args[3] != mp_const_none) {
	#if MICROPY_PY_BUILTINS_FLOAT
	float timeout_f = mp_obj_get_float(args[3]);
	if (timeout_f >= 0) {
	timeout = (mp_uint_t)(timeout_f * 1000);
	}
	#else
	timeout = mp_obj_get_int(args[3]) * 1000;
	#endif
	}
	}

	// merge separate lists and get the ioctl function for each object
	mp_map_t poll_map;
	mp_map_init(&poll_map, rwx_len[0] + rwx_len[1] + rwx_len[2]);
	poll_map_add(&poll_map, r_array, rwx_len[0], MP_STREAM_POLL_RD, true);
	poll_map_add(&poll_map, w_array, rwx_len[1], MP_STREAM_POLL_WR, true);
	poll_map_add(&poll_map, x_array, rwx_len[2], MP_STREAM_POLL_ERR \| MP_STREAM_POLL_HUP, true);

	mp_uint_t start_tick = mp_hal_ticks_ms();
	rwx_len[0] = rwx_len[1] = rwx_len[2] = 0;
	for (;;) {
	// poll the objects
	mp_uint_t n_ready = poll_map_poll(&poll_map, rwx_len);

	if (n_ready > 0 \|\| (timeout != -1 && mp_hal_ticks_ms() - start_tick >= timeout)) {
	// one or more objects are ready, or we had a timeout
	mp_obj_t list_array[3];
	list_array[0] = mp_obj_new_list(rwx_len[0], NULL);
	list_array[1] = mp_obj_new_list(rwx_len[1], NULL);
	list_array[2] = mp_obj_new_list(rwx_len[2], NULL);
	rwx_len[0] = rwx_len[1] = rwx_len[2] = 0;
	for (mp_uint_t i = 0; i < poll_map.alloc; ++i) {
	if (!MP_MAP_SLOT_IS_FILLED(&poll_map, i)) {
	continue;
	}
	poll_obj_t poll_obj = (poll_obj_t)poll_map.table[i].value;
	if (poll_obj->flags_ret & MP_STREAM_POLL_RD) {
	((mp_obj_list_t*)list_array[0])->items[rwx_len[0]++] = poll_obj->obj;
	}
	if (poll_obj->flags_ret & MP_STREAM_POLL_WR) {
	((mp_obj_list_t*)list_array[1])->items[rwx_len[1]++] = poll_obj->obj;
	}
	if ((poll_obj->flags_ret & ~(MP_STREAM_POLL_RD \| MP_STREAM_POLL_WR)) != 0) {
	((mp_obj_list_t*)list_array[2])->items[rwx_len[2]++] = poll_obj->obj;
	}
	}
	mp_map_deinit(&poll_map);
	return mp_obj_new_tuple(3, list_array);
	}
	MICROPY_EVENT_POLL_HOOK
	}
	}
	MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_select_select_obj, 3, 4, select_select);

	/// \class Poll - poll class

	typedef struct _mp_obj_poll_t {
	mp_obj_base_t base;
	mp_map_t poll_map;
	short iter_cnt;
	short iter_idx;
	int flags;
	// callee-owned tuple
	mp_obj_t ret_tuple;
	} mp_obj_poll_t;

	/// \method register(obj[, eventmask])
	STATIC mp_obj_t poll_register(uint n_args, const mp_obj_t *args) {
	mp_obj_poll_t *self = args[0];
	mp_uint_t flags;
	if (n_args == 3) {
	flags = mp_obj_get_int(args[2]);
	} else {
	flags = MP_STREAM_POLL_RD \| MP_STREAM_POLL_WR;
	}
	poll_map_add(&self->poll_map, &args[1], 1, flags, false);
	return mp_const_none;
	}
	MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_register_obj, 2, 3, poll_register);

	/// \method unregister(obj)
	STATIC mp_obj_t poll_unregister(mp_obj_t self_in, mp_obj_t obj_in) {
	mp_obj_poll_t *self = self_in;
	mp_map_lookup(&self->poll_map, mp_obj_id(obj_in), MP_MAP_LOOKUP_REMOVE_IF_FOUND);
	// TODO raise KeyError if obj didn't exist in map
	return mp_const_none;
	}
	MP_DEFINE_CONST_FUN_OBJ_2(poll_unregister_obj, poll_unregister);

	/// \method modify(obj, eventmask)
	STATIC mp_obj_t poll_modify(mp_obj_t self_in, mp_obj_t obj_in, mp_obj_t eventmask_in) {
	mp_obj_poll_t *self = self_in;
	mp_map_elem_t *elem = mp_map_lookup(&self->poll_map, mp_obj_id(obj_in), MP_MAP_LOOKUP);
	if (elem == NULL) {
	mp_raise_OSError(MP_ENOENT);
	}
	((poll_obj_t*)elem->value)->flags = mp_obj_get_int(eventmask_in);
	return mp_const_none;
	}
	MP_DEFINE_CONST_FUN_OBJ_3(poll_modify_obj, poll_modify);

	STATIC mp_uint_t poll_poll_internal(uint n_args, const mp_obj_t *args) {
	mp_obj_poll_t *self = args[0];

	// work out timeout (its given already in ms)
	mp_uint_t timeout = -1;
	int flags = 0;
	if (n_args >= 2) {
	if (args[1] != mp_const_none) {
	mp_int_t timeout_i = mp_obj_get_int(args[1]);
	if (timeout_i >= 0) {
	timeout = timeout_i;
	}
	}
	if (n_args >= 3) {
	flags = mp_obj_get_int(args[2]);
	}
	}

	self->flags = flags;

	mp_uint_t start_tick = mp_hal_ticks_ms();
	mp_uint_t n_ready;
	for (;;) {
	// poll the objects
	n_ready = poll_map_poll(&self->poll_map, NULL);
	if (n_ready > 0 \|\| (timeout != -1 && mp_hal_ticks_ms() - start_tick >= timeout)) {
	break;
	}
	MICROPY_EVENT_POLL_HOOK
	}

	return n_ready;
	}

	STATIC mp_obj_t poll_poll(uint n_args, const mp_obj_t *args) {
	mp_obj_poll_t *self = args[0];
	mp_uint_t n_ready = poll_poll_internal(n_args, args);

	// one or more objects are ready, or we had a timeout
	mp_obj_list_t *ret_list = mp_obj_new_list(n_ready, NULL);
	n_ready = 0;
	for (mp_uint_t i = 0; i < self->poll_map.alloc; ++i) {
	if (!MP_MAP_SLOT_IS_FILLED(&self->poll_map, i)) {
	continue;
	}
	poll_obj_t poll_obj = (poll_obj_t)self->poll_map.table[i].value;
	if (poll_obj->flags_ret != 0) {
	mp_obj_t tuple[2] = {poll_obj->obj, MP_OBJ_NEW_SMALL_INT(poll_obj->flags_ret)};
	ret_list->items[n_ready++] = mp_obj_new_tuple(2, tuple);
	if (self->flags & FLAG_ONESHOT) {
	// Don't poll next time, until new event flags will be set explicitly
	poll_obj->flags = 0;
	}
	}
	}
	return ret_list;
	}
	MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_poll_obj, 1, 3, poll_poll);

	STATIC mp_obj_t poll_ipoll(size_t n_args, const mp_obj_t *args) {
	mp_obj_poll_t *self = MP_OBJ_TO_PTR(args[0]);

	if (self->ret_tuple == MP_OBJ_NULL) {
	self->ret_tuple = mp_obj_new_tuple(2, NULL);
	}

	int n_ready = poll_poll_internal(n_args, args);
	self->iter_cnt = n_ready;
	self->iter_idx = 0;

	return args[0];
	}
	MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(poll_ipoll_obj, 1, 3, poll_ipoll);

	STATIC mp_obj_t poll_iternext(mp_obj_t self_in) {
	mp_obj_poll_t *self = MP_OBJ_TO_PTR(self_in);

	if (self->iter_cnt == 0) {
	return MP_OBJ_STOP_ITERATION;
	}

	self->iter_cnt--;

	for (mp_uint_t i = self->iter_idx; i < self->poll_map.alloc; ++i) {
	self->iter_idx++;
	if (!MP_MAP_SLOT_IS_FILLED(&self->poll_map, i)) {
	continue;
	}
	poll_obj_t poll_obj = (poll_obj_t)self->poll_map.table[i].value;
	if (poll_obj->flags_ret != 0) {
	mp_obj_tuple_t *t = MP_OBJ_TO_PTR(self->ret_tuple);
	t->items[0] = poll_obj->obj;
	t->items[1] = MP_OBJ_NEW_SMALL_INT(poll_obj->flags_ret);
	if (self->flags & FLAG_ONESHOT) {
	// Don't poll next time, until new event flags will be set explicitly
	poll_obj->flags = 0;
	}
	return MP_OBJ_FROM_PTR(t);
	}
	}

	assert(!"inconsistent number of poll active entries");
	self->iter_cnt = 0;
	return MP_OBJ_STOP_ITERATION;
	}

	STATIC const mp_rom_map_elem_t poll_locals_dict_table[] = {
	{ MP_ROM_QSTR(MP_QSTR_register), MP_ROM_PTR(&poll_register_obj) },
	{ MP_ROM_QSTR(MP_QSTR_unregister), MP_ROM_PTR(&poll_unregister_obj) },
	{ MP_ROM_QSTR(MP_QSTR_modify), MP_ROM_PTR(&poll_modify_obj) },
	{ MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&poll_poll_obj) },
	{ MP_ROM_QSTR(MP_QSTR_ipoll), MP_ROM_PTR(&poll_ipoll_obj) },
	};
	STATIC MP_DEFINE_CONST_DICT(poll_locals_dict, poll_locals_dict_table);

	STATIC const mp_obj_type_t mp_type_poll = {
	{ &mp_type_type },
	.name = MP_QSTR_poll,
	.getiter = mp_identity_getiter,
	.iternext = poll_iternext,
	.locals_dict = (void*)&poll_locals_dict,
	};

	/// \function poll()
	STATIC mp_obj_t select_poll(void) {
	mp_obj_poll_t *poll = m_new_obj(mp_obj_poll_t);
	poll->base.type = &mp_type_poll;
	mp_map_init(&poll->poll_map, 0);
	poll->iter_cnt = 0;
	poll->ret_tuple = MP_OBJ_NULL;
	return poll;
	}
	MP_DEFINE_CONST_FUN_OBJ_0(mp_select_poll_obj, select_poll);

	STATIC const mp_rom_map_elem_t mp_module_select_globals_table[] = {
	{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uselect) },
	{ MP_ROM_QSTR(MP_QSTR_select), MP_ROM_PTR(&mp_select_select_obj) },
	{ MP_ROM_QSTR(MP_QSTR_poll), MP_ROM_PTR(&mp_select_poll_obj) },
	{ MP_ROM_QSTR(MP_QSTR_POLLIN), MP_ROM_INT(MP_STREAM_POLL_RD) },
	{ MP_ROM_QSTR(MP_QSTR_POLLOUT), MP_ROM_INT(MP_STREAM_POLL_WR) },
	{ MP_ROM_QSTR(MP_QSTR_POLLERR), MP_ROM_INT(MP_STREAM_POLL_ERR) },
	{ MP_ROM_QSTR(MP_QSTR_POLLHUP), MP_ROM_INT(MP_STREAM_POLL_HUP) },
	};

	STATIC MP_DEFINE_CONST_DICT(mp_module_select_globals, mp_module_select_globals_table);

	const mp_obj_module_t mp_module_uselect = {
	.base = { &mp_type_module },
	.globals = (mp_obj_dict_t*)&mp_module_select_globals,
	};

	#endif // MICROPY_PY_USELECT