For Regular and Periodic BSR:

if more than one LCG has data AVAILABLE for transmission in the TTI where the BSR is transmitted

report LONG BSR
 else,
 report Short BSR.

For Padding BSR: if the number of padding bits is equal to or larger than the size of the Short BSR PLUS its subheader but smaller than the size of the Long BSR plus its subheader:

if more than one LCG has data available for transmission in the TTI where the BSR is transmitted: report Truncated BSR of the LCG with the highest priority logical CHANNEL with data available for transmission;
else 
report Short BSR.

else if the number of padding bits is equal to or larger than the size of the Long BSR plus its subheader, report Long BSR.

For Regular and Periodic BSR:

if more than one LCG has data available for transmission in the TTI where the BSR is transmitted

report Long BSR
 else,
 report Short BSR.

For Padding BSR: if the number of padding bits is equal to or larger than the size of the Short BSR plus its subheader but smaller than the size of the Long BSR plus its subheader:

if more than one LCG has data available for transmission in the TTI where the BSR is transmitted: report Truncated BSR of the LCG with the highest priority logical channel with data available for transmission;
else 
report Short BSR.

else if the number of padding bits is equal to or larger than the size of the Long BSR plus its subheader, report Long BSR.