2 loop nesting rules, 3 loop la rules, Loop nesting rules -53 – Freescale Semiconductor StarCore SC140 User Manual
Page 303: Loop la rules -53, Lfn enabled at lpa or lpb -53, Instructions at the end of long loops -53
LPMARK Rules
SC140 DSP Core Reference Manual
7-53
7.8.3.1.2 Active SAn Register
“Active SAn register” is defined as the SAn register where n = the active loop index. This definition is
dynamic and follows the SC140 loop state machine.
7.8.3.1.3 Active LCn Register
“Active LCn register” is defined as the LCn register where n = the active loop index. This definition is
dynamic and follows the SC140 loop state machine.
7.8.3.2 Loop Nesting Rules
LPMARK Rule L.N.5
At least one LFn status bit in SR must be set at LPA or LPB of a loop.
Example 7-91. LFn Enabled at LPA or LPB
dosetup1 label1
doen1 #5
pop sr
;pop clears all LFn
...
label1
nop
{lpmarkb set}
;not allowed
nop
nop
7.8.3.3 Loop LA Rules
LPMARK Rule L.L.1
The following instructions are not allowed at LPB+1 or LPB+2 of a long loop:
•
COF instructions
•
STOP and WAIT
•
DI
•
DEBUG
Example 7-92. Instructions at the End of Long Loops
move.w #count2,d6
dosetup0 label2
doen0 d6
move.w #1,d1
move.w #2,d2
move.w #3,d3
move.w #4,d4
label2 inc d1
inc d2
inc d3
{lpmarkb set}
inc d4
wait
;not allowed