extmod/machine_signal: Implement "signal" abstraction for machine module.

A signal is like a pin, but ca also be inverted (active low). As such, it
abstracts properties of various physical devices, like LEDs, buttons,
relays, buzzers, etc. To instantiate a Signal:

pin = machine.Pin(...)
signal = machine.Signal(pin, inverted=True)

signal has the same .value() and __call__() methods as a pin.

extmod/machine_signal.c

@@ -0,0 +1,114 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 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 "py/mpconfig.h"
+#if MICROPY_PY_MACHINE
+
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "extmod/virtpin.h"
+#include "extmod/machine_signal.h"
+
+// Signal class
+
+typedef struct _machine_signal_t {
+    mp_obj_base_t base;
+    mp_obj_t pin;
+    bool inverted;
+} machine_signal_t;
+
+STATIC mp_obj_t signal_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    enum { ARG_pin, ARG_inverted };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_, MP_ARG_OBJ | MP_ARG_REQUIRED },
+        { MP_QSTR_inverted, MP_ARG_BOOL, {.u_bool = false} },
+    };
+
+    mp_arg_val_t parsed_args[MP_ARRAY_SIZE(allowed_args)];
+
+    mp_arg_parse_all_kw_array(n_args, n_kw, args, MP_ARRAY_SIZE(allowed_args), allowed_args, parsed_args);
+
+    machine_signal_t *o = m_new_obj(machine_signal_t);
+    o->base.type = type;
+    o->pin = parsed_args[ARG_pin].u_obj;
+    o->inverted = parsed_args[ARG_inverted].u_bool;
+    return MP_OBJ_FROM_PTR(o);
+}
+
+STATIC mp_uint_t signal_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
+    (void)errcode;
+    machine_signal_t *self = MP_OBJ_TO_PTR(self_in);
+
+    switch (request) {
+        case MP_PIN_READ: {
+            return mp_virtual_pin_read(self->pin) ^ self->inverted;
+        }
+        case MP_PIN_WRITE: {
+            mp_virtual_pin_write(self->pin, arg ^ self->inverted);
+            return 0;
+        }
+    }
+    return -1;
+}
+
+// fast method for getting/setting signal value
+STATIC mp_obj_t signal_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
+    mp_arg_check_num(n_args, n_kw, 0, 1, false);
+    if (n_args == 0) {
+        // get pin
+        return MP_OBJ_NEW_SMALL_INT(mp_virtual_pin_read(self_in));
+    } else {
+        // set pin
+        mp_virtual_pin_write(self_in, mp_obj_is_true(args[0]));
+        return mp_const_none;
+    }
+}
+
+STATIC mp_obj_t signal_value(size_t n_args, const mp_obj_t *args) {
+    return signal_call(args[0], n_args - 1, 0, args + 1);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(signal_value_obj, 1, 2, signal_value);
+
+STATIC const mp_rom_map_elem_t signal_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_value), MP_ROM_PTR(&signal_value_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(signal_locals_dict, signal_locals_dict_table);
+
+STATIC const mp_pin_p_t signal_pin_p = {
+    .ioctl = signal_ioctl,
+};
+
+const mp_obj_type_t machine_signal_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Signal,
+    .make_new = signal_make_new,
+    .call = signal_call,
+    .protocol = &signal_pin_p,
+    .locals_dict = (void*)&signal_locals_dict,
+};
+
+#endif // MICROPY_PY_MACHINE

extmod/machine_signal.h

@@ -0,0 +1,35 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 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.
+ */
+
+
+#ifndef __MICROPY_INCLUDED_EXTMOD_MACHINE_SIGNAL_H__
+#define __MICROPY_INCLUDED_EXTMOD_MACHINE_SIGNAL_H__
+
+#include "py/obj.h"
+
+extern const mp_obj_type_t machine_signal_type;
+
+#endif // __MICROPY_INCLUDED_EXTMOD_MACHINE_SIGNAL_H__

py/py.mk

@@ -222,6 +222,7 @@ PY_O_BASENAME = \
 	../extmod/virtpin.o \
 	../extmod/machine_mem.o \
 	../extmod/machine_pinbase.o \
+	../extmod/machine_signal.o \
 	../extmod/machine_pulse.o \
 	../extmod/machine_i2c.o \
 	../extmod/machine_spi.o \