Writing to GPIO_OUT_REG to only specific pins

[Deouss]

Let's say I want to set 12 bits/pins simultaneously with specific values 0/1 to gpio output register but I do not want to change other bits - must be done with one 32bit word write and possibly one write instruction.
Do I have to disable/enable bits with mask first? I don't want to change settings of other pins.
Should it be done with combination of W1TC/W1TS ?
I am looking for fastest possible way - best with asm instructions if possible. Single REG_WRITE is ok too.
Thanks for any suggestions

[ESP_Sprite]

There's no way to mask bits; the way to go would be to either use a read/modify/write on the GPIO value register (but watch out with multitasking there) or use a W1TC/W1TS combo. From an architectural point of view, I'd think W1TS/W1TC would be faster (no reads involved, writes can be queued) but it does have the slight disadvantage that you have an intermediate value on your GPIOs at some point.

[Deouss]

So operations steps would be:

val => W1TS
val ~= val
val => W1TC

How that would look in asm ?

[ESP_Sprite]

So operations steps would be:

val => W1TS
val ~= val
val => W1TC

How that would look in asm ?

You probably want to mask the bits you don't want to touch.

W1TS <= val & mask
W1TC <= (~val) & mask

I'll leave the assembly to someone else, but chances are it's not going to be that much faster than C. (Maybe a bit because C declares these as volatile; you could work around that though.)

[Deouss]

Thanks. Well I use whole word only with needed bits so masking is not necessary.
Actually XOR operation might not be needed and data will be precalculated ready to write)
I want to use assembler instructions to repeat inline few times for speeding execution.