Usage of 1UL

[JK0201]

Hello to everyone.

I´m trying to understand a code starting from the file of definition of pins of nRF52 PCA10040.
In "simple_hal.c" there's a line like this: NRF_GPIO->OUTSET = 1UL << i;     in the hall_leds_init() function.
To know the complete tasks of this function, I have to know what does "1UL" do.
So, my question is: what does "1UL" do?
I know too that 1UL is used in another .c fles, but I don't know if it do the same function on those codes.

I hope you can help me.

[Susheel Nuguru]

1UL just means 1 (unsigned long) and the width of which is architectural specific. Write like this is a good practice if you are writing a code for manipulating contents of registers so that the compilers do what you expect them to do.

[JK0201]

I see, so in this way, this 1 is compatible with any assignation?