Analog Devices ADSP-BF53x Blackfin, Reference

Page: 322 / 1042

Instruction Overview
7-18 ADSP-BF53x/BF56x Blackfin Processor Programming Reference
As long as the hardware loop is active (
Loop_Count
is nonzero), any of
these forbidden instructions at the
End_Loop
address produces undefined
execution, and no exception is generated. Forbidden
End_Loop
instructions that appear anywhere else in the defined loop execute nor-
mally. Branch instructions that are located anywhere else in the defined
loop execute normally.
Also, the last instruction in the loop must not modify the registers that
define the currently active loop (
LCn
,
LTn
, or
LBn
). User modifications to
those registers while the hardware accesses them produces undefined exe-
cution. Software can legally modify the loop counter at any other location
in the loop.
Flags Affected
None
Required Mode
User & Supervisor
Parallel Issue
This instruction cannot be issued in parallel with other instructions.
Example
lsetup ( 4, 4 ) lc0 ;
lsetup ( poll_bit, end_poll_bit ) lc0 ;
lsetup ( 4, 6 ) lc1 ;
lsetup ( FIR_filter, bottom_of_FIR_filter ) lc1 ;
lsetup ( 4, 8 ) lc0 = p1 ;
lsetup ( 4, 8 ) lc0 = p1>>1 ;