esp8266/machine_pin: Implement Pin.toggle() method.

Tested with a generic ESP8266 device.  The actual output value is taken
from the output register, not by reading the pad level.

Signed-off-by: robert-hh <robert@hammelrath.com>

Author: robert-hh

ports/esp8266/esp_mphal.h

@@ -100,6 +100,13 @@ void mp_hal_pin_open_drain(mp_hal_pin_obj_t pin);
         else { gpio_output_set(1 << (p), 0, 1 << (p), 0); } \
 } while (0)
 #define mp_hal_pin_read(p) pin_get(p)
+static inline int mp_hal_pin_read_output(mp_hal_pin_obj_t pin) {
+    if (pin >= 16) {
+        return READ_PERI_REG(RTC_GPIO_OUT) & 1;
+    } else {
+        return (GPIO_REG_READ(GPIO_OUT_ADDRESS) >> pin) & 1;
+    }
+}
 #define mp_hal_pin_write(p, v) pin_set((p), (v))
 
 void *ets_get_esf_buf_ctlblk(void);

ports/esp8266/machine_pin.c

@@ -373,6 +373,14 @@ static mp_obj_t pyb_pin_on(mp_obj_t self_in) {
 }
 static MP_DEFINE_CONST_FUN_OBJ_1(pyb_pin_on_obj, pyb_pin_on);
 
+// pin.toggle()
+static mp_obj_t machine_pin_toggle(mp_obj_t self_in) {
+    pyb_pin_obj_t *self = self_in;
+    pin_set(self->phys_port, 1 - mp_hal_pin_read_output(self->phys_port));
+    return mp_const_none;
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(machine_pin_toggle_obj, machine_pin_toggle);
+
 // pin.irq(handler=None, trigger=IRQ_FALLING|IRQ_RISING, hard=False)
 static mp_obj_t pyb_pin_irq(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     enum { ARG_handler, ARG_trigger, ARG_hard };
@@ -435,6 +443,7 @@ static const mp_rom_map_elem_t pyb_pin_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_value),   MP_ROM_PTR(&pyb_pin_value_obj) },
     { MP_ROM_QSTR(MP_QSTR_off),     MP_ROM_PTR(&pyb_pin_off_obj) },
     { MP_ROM_QSTR(MP_QSTR_on),      MP_ROM_PTR(&pyb_pin_on_obj) },
+    { MP_ROM_QSTR(MP_QSTR_toggle), MP_ROM_PTR(&machine_pin_toggle_obj) },
     { MP_ROM_QSTR(MP_QSTR_irq),     MP_ROM_PTR(&pyb_pin_irq_obj) },
 
     // class constants