Windbg Pseudo Director Extension

Question

I am trying to automate a debugging session of a device driver in Windows XP using Windbg. My device has a register "index" and a register of "data", both are displayed in memory. The index register must be populated with an internal register index, and the value can be read from the data register. So, the followind Windbg command correctly prints the value of the internal register 0x4C:

!ed [uc] 0xfa000000 0x4c; !dd [uc] 0xfa000004 L1 

Now I would like to reset the range of internal registers, but it looks like the alias extension is not working properly on the command! ed. I try this loop:

 .for (r $t0=0; @$t0<0x100; r $t0=@ $t0+1) { !ed [uc] 0xfa000000 @$t0; !dd [uc] 0xfa000004 L1 } 

but it seems like a team! ed is ignored as if @ $ t0 were expanded on an empty line. Tried "$ t0", "@ $ t0", "$ {t0}" and "@ $ {t0}", but to no avail. What am I doing wrong?

Answer 1

Yes, it seems ed doesn't evaluate its arguments like other commands. You must evaluate them in advance, for example, using an alias, for example:

 .for (r $t0=0; @$t0<0x100; r $t0=@ $t0+1) { as /x val @$t0 ; .block {!ed [uc] 0xfa000000 ${val} ; !dd [uc] 0xfa000004 L1 } }