rp2pio: fix occasional bug when not using OUT pins

jepler · jepler · commit a3e17189a489 · 2022-09-03T20:39:42.000-05:00
a NULL first pin object is used to indicate that there are zero
of some kind of pin associated with the StateMachine. However,
mask_and_rotate wasn't checking for zero. It actually read data from
near address 0x0 and (in my case) got a nonzero mask, which then
caused a program with GPIO11 and GPIO12 as input with pull-up and no
out pins to erroneously encounter the error "pull masks conflict with
direction masks"
diff --git a/ports/raspberrypi/common-hal/rp2pio/StateMachine.c b/ports/raspberrypi/common-hal/rp2pio/StateMachine.c
@@ -369,6 +369,9 @@ bool rp2pio_statemachine_construct(rp2pio_statemachine_obj_t *self,
 }
 
 static uint32_t mask_and_rotate(const mcu_pin_obj_t *first_pin, uint32_t bit_count, uint32_t value) {
+    if (!first_pin) {
+        return 0;
+    }
     value = value & ((1 << bit_count) - 1);
     uint32_t shift = first_pin->number;
     return value << shift | value >> (32 - shift);

Original file line number	Diff line number	Diff line change
`@@ -369,6 +369,9 @@ bool rp2pio_statemachine_construct(rp2pio_statemachine_obj_t *self,`
`369`	`369`	`}`
`370`	`370`
`371`	`371`	`static uint32_t mask_and_rotate(const mcu_pin_obj_t *first_pin, uint32_t bit_count, uint32_t value) {`
	`372`	`+ if (!first_pin) {`
	`373`	`+ return 0;`
	`374`	`+ }`
`372`	`375`	`value = value & ((1 << bit_count) - 1);`
`373`	`376`	`uint32_t shift = first_pin->number;`
`374`	`377`	`return value << shift \| value >> (32 - shift);`