cmsis-svd crashing on getting derived registers

[Jegeva]

Hello,

on :
LPC178x_7x svd
LPC178x_7x_v0.8 svd
LPC408x_7x_v0.7.svd
files that are included in the data ,
it crashes on trying to iterate on the registers,

More specifically it crashes on this element of the SVDs :

<peripheral derivedFrom="SSP0"> <name>SSP2</name> <baseAddress>0x400AC000</baseAddress> <interrupt> <name>SSP2</name> <value>36</value> </interrupt> </peripheral>

here is the TB
Traceback (most recent call last):
File "./idarm-make-regtag.py", line 241, in
data = get_data_for(args.vendor, args.chip ,args.max_segment_sz_int,args,1)
File "./idarm-make-regtag.py", line 99, in get_data_for
regs = peripheral.registers
File "./cmsis-svd/python/cmsis_svd/model.py", line 502, in registers
for reg in self._lookup_possibly_derived_attribute('registers'):
TypeError: 'NoneType' object is not iterable

---

digging deeper, i saw that SSP0 is derived from SSP1. changing the peripheral SSP2 is derived from to SSP1 fixes the crash which leads me to think that cmsis-svd isn't handling the daisy chaining of derivedFrom case correctly (and i don't know if this is even legal to start with but that is in the base data package and looking at http://www.keil.com/pack/doc/CMSIS/SVD/html/schema_1_2_gr.html i don't see why you couldn't chain derived elements)

[Jegeva]

see pull #97 for a data fix but not a fix of the underlying issue