need calrification

[bijutalukdar]

Hi Antonin,
file register.p4
line 68, 69
modify_field_rng_uniform(meta.register_tmp, 100, 200);
register_write(my_register, register_idx, meta.register_tmp);

Could you please refer to some doc where I find what these functions are doing. Intuitively I can understand , but which parameter is getting written where is somewhat obscure to me.

Also I have seen these command used through cli at runtime to update the switch tables:

table_set_default m_table m_action
table_add m_table m_action aa:bb:cc:dd:ee:ff => 0

what does that do exactly. Again if there is any quick readme on that please share.

[antoninbas]

Note that the code in the m_action in register.p4 is irrelevant to the demo itself and is just here to showcase what can be done with registers.
That being said:

• modify_field_rng_uniform(hdrA.f1, a, b): generates a random integer between a and b and assigns it to field hdrA.f1
• register_write(reg, idx, hdrA.f1): assigns the value of field hdrA.f1 (can also be a constant) to reg[idx].
• register_read(hdrA.f1, reg, idx): assigns the value of reg[idx] to field hdrA.f1.

When you want to check exactly what a primitive is doing, you can directly refer to this file (https://github.com/p4lang/behavioral-model/blob/master/targets/simple_switch/primitives.h) which implements each standard primitive (usually only a few lines of code per primitive).

You can get some basic help for CLI commands by typing help <command> in the CLI itself. I believe these slides (http://p4.org/wp-content/uploads/2015/12/Nov-2015-P4-Bootcamp-Labs-Guide.pdf) from the 1st P4 bootcamp include more information on how to use the CLI. There is not yet a complete user guide on how to use the CLI.

[bijutalukdar]

great help thanks a ton