ASN.1 PER ALIGNED RNSAP decoding

Hi,
Can any one help with algorithm of RNSAP decoding, coded with ASN.1 (existing libraries for ASN.1 decoding can’t be used)

What are the rules for coding of the next structure

Extension-DedicatedMeasurementValue ::= ProtocolIE-Single-Container {{ Extension-DedicatedMeasurementValueIE }}

Extension-DedicatedMeasurementValueIE RNSAP-PROTOCOL-IES ::= {
{ ID id-Rx-Timing-Deviation-Value-LCR CRITICALITY reject TYPE Rx-Timing-Deviation-Value-LCR PRESENCE mandatory }|
{ ID id-Angle-Of-Arrival-Value-LCR CRITICALITY reject TYPE Angle-Of-Arrival-Value-LCR PRESENCE mandatory }|
{ ID id-HS-SICH-Reception-Quality CRITICALITY reject TYPE HS-SICH-Reception-Quality-Value PRESENCE mandatory }|
{ ID id-Rx-Timing-Deviation-Value-768 CRITICALITY reject TYPE Rx-Timing-Deviation-Value-768 PRESENCE mandatory }|
{ ID id-Rx-Timing-Deviation-Value-ext CRITICALITY reject TYPE Rx-Timing-Deviation-Value-ext PRESENCE mandatory }|
{ ID id-Extended-Round-Trip-Time-Value CRITICALITY reject TYPE Extended-Round-Trip-Time-Value PRESENCE mandatory },

}

When length should be add to bit field?
Thank’s in advancem