After a weekend of searching and trying, here is what I was looking for:

It is slightly different than for the AVR chips. There is one register for setting the pins to HIGH and another one to set the pins to low.

Setting the pin HIGH:

GPOS = (1 << PIN_OUT);

Setting the pin LOW:

GPOC = (1 << PIN_OUT);

using this, I managed to speed up my code by a factor of three. It is not as dramatic as for the AVR chips, since the digitalWrite function is much more simple for the ESP8266.

Its much faster: digitalWrite() 910nsec vs. GPOC or GPOS 88nsec !! (WS 1 februari 2021)

After a weekend of searching and trying, here is what I was looking for:

It is slightly different than for the AVR chips. There is one register for setting the pins to HIGH and another one to set the pins to low.

Setting the pin HIGH:

GPOS = (1 << PIN_OUT);

Setting the pin LOW:

GPOC = (1 << PIN_OUT);

using this, I managed to speed up my code by a factor of three. It is not as dramatic as for the AVR chips, since the digitalWrite function is much more simple for the ESP8266.

Edit Further experiments show it is 10x faster: 910nsec for digitalWrite vs. 88nsec using GPOC or GPOS!

After a weekend of searching and trying, here is what I was looking for:

It is slightly different than for the AVR chips. There is one register for setting the pins to HIGH and another one to set the pins to low.

Setting the pin HIGH:

GPOS = (1 << PIN_OUT);

Setting the pin LOW:

GPOC = (1 << PIN_OUT);

using this, I managed to speed up my code by a factor of three. It is not as dramatic as for the AVR chips, since the digitalWrite function is much more simple for the ESP8266.

After a weekend of searching and trying, here is what I was looking for:

It is slightly different than for the AVR chips. There is one register for setting the pins to HIGH and another one to set the pins to low.

Setting the pin HIGH:

GPOS = (1 << PIN_OUT);

Setting the pin LOW:

GPOC = (1 << PIN_OUT);

using this, I managed to speed up my code by a factor of three. It is not as dramatic as for the AVR chips, since the digitalWrite function is much more simple for the ESP8266.

Its much faster: digitalWrite() 910nsec vs. GPOC or GPOS 88nsec !! (WS 1 februari 2021)