examples: Mark asm, pio, etc. as noqa: F821 (undefined-name).

These files all use decorators (@asm_thumb, @asm_pio) that add names to the
function scope, that the linter cannot see.

It's useful to clear them in the file not in pyproject.toml as example code
will be copied and adapted elsewhere, and those developers may also use
Ruff (we hope!)

Signed-off-by: Angus Gratton <angus@redyak.com.au>

examples/asmled.py

@@ -1,5 +1,9 @@
 # flash LED #1 using inline assembler
 # this version is overly verbose and uses word stores
+#
+# ruff: noqa: F821 - @asm_thumb decorator adds names to function scope
+
+
 @micropython.asm_thumb
 def flash_led(r0):
     movw(r1, (stm.GPIOA + stm.GPIO_BSRRL) & 0xFFFF)

examples/asmsum.py

@@ -1,3 +1,6 @@
+# ruff: noqa: F821 - @asm_thumb decorator adds names to function scope
+
+
 @micropython.asm_thumb
 def asm_sum_words(r0, r1):
     # r0 = len

examples/natmod/btree/btree_py.py

@@ -1,3 +1,7 @@
 # Implemented in Python to support keyword arguments
+
+# ruff: noqa: F821 - this file is evaluated with C-defined names in scope
+
+
 def open(stream, *, flags=0, cachesize=0, pagesize=0, minkeypage=0):
     return _open(stream, flags, cachesize, pagesize, minkeypage)

examples/natmod/features2/test.py

@@ -1,5 +1,7 @@
 # This Python code will be merged with the C code in main.c
 
+# ruff: noqa: F821 - this file is evaluated with C-defined names in scope
+
 import array
 
 

examples/rp2/pio_1hz.py

@@ -1,6 +1,8 @@
 # Example using PIO to blink an LED and raise an IRQ at 1Hz.
 # Note: this does not work on Pico W because it uses Pin(25) for LED output.
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import time
 from machine import Pin
 import rp2

examples/rp2/pio_exec.py

@@ -5,6 +5,8 @@
 #   - using set_init and set_base
 #   - using StateMachine.exec
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import time
 from machine import Pin
 import rp2

examples/rp2/pio_pinchange.py

@@ -8,6 +8,8 @@
 #   - setting an irq handler for a StateMachine
 #   - instantiating 2x StateMachine's with the same program and different pins
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import time
 from machine import Pin
 import rp2

examples/rp2/pio_pwm.py

@@ -1,5 +1,7 @@
 # Example of using PIO for PWM, and fading the brightness of an LED
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 from machine import Pin
 from rp2 import PIO, StateMachine, asm_pio
 from time import sleep

examples/rp2/pio_uart_rx.py

@@ -8,6 +8,8 @@
 #   - PIO irq handler
 #   - using the second core via _thread
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import _thread
 from machine import Pin, UART
 from rp2 import PIO, StateMachine, asm_pio

examples/rp2/pio_uart_tx.py

@@ -1,5 +1,7 @@
 # Example using PIO to create a UART TX interface
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 from machine import Pin
 from rp2 import PIO, StateMachine, asm_pio
 

examples/rp2/pio_ws2812.py

@@ -1,5 +1,7 @@
 # Example using PIO to drive a set of WS2812 LEDs.
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import array, time
 from machine import Pin
 import rp2

examples/rp2/pwm_fade.py

@@ -1,6 +1,8 @@
 # Example using PWM to fade an LED.
 # Note: this does not work on Pico W because it uses Pin(25) for LED output.
 
+# ruff: noqa: F821 - @asm_pio decorator adds names to function scope
+
 import time
 from machine import Pin, PWM
 

ports/qemu-arm/test-frzmpy/frozen_asm.py

@@ -1,5 +1,7 @@
 # Test freezing inline-asm code.
 
+# ruff: noqa: F821 - @asm_thumb decorator adds names to function scope
+
 import micropython