[ixp1200] where is the initilization of the buffer descriptors (SRAM Push) ?

[KIM, IK KYUN]

I am studying the buffer management of IXP 1200.

But I can not find the location of initialization of buffer descriptors (SRAM Buffer descriptor).

Obviously I confirmed that :  when packet is arriving at Ingress micro ace,  
 Ingress Micro ACE gets the buffer descriptor for SDRAM from SRAM using the instruction "sram[pop,....]".

I am not sure, buffer descriptor initilazation is executed  "on Micro block" OR  "on ARM core".

I would like to know the exact initialization code (uc or cpp).

Thanks.