
7-54 SC140 DSP Core Reference Manual
LPMARK Rules
LPMARK Rule L.L.2
A DOENn or MOVE-like instruction that writes the active LCn register is not allowed at LPB, LPB+1, or
LPB+2 of a long loop.
Example 7-93. Active LCn Write at the End of Long Loops
doen1 #3
move.l #$12345678,r1
inc d0 {lpmarkb set}
doen1 #5 ;not allowed
move.w d3,(r1)+
LPMARK Rule L.L.3
The following instructions are not allowed at LPA, LPB, or LPB+1 of a short loop:
• COF instructions
• STOP and WAIT
• DI
• DEBUG
• DOENn/DOENSHn
• MOVE-like instructions that read any LCn register
• MOVE-like instructions that write any LCn register
• MOVE-like instructions that read the SR register
• MOVE-like instructions that write the SR register
This rule does not apply to other instructions that affect status bits in SR.
Example 7-94. Instructions in Short Loops
move.w #count2,r6
doensh0 r6
move.w #3,d3
inc d3 {lpmarkb set}
wait ;not allowed
doensh0 #$10
nop
jmp end {lpmarka set} ;not allowed
doensh1 #count2
move.w #num,d2
doen1 #5 {lpmarka set} ;not allowed
LPMARK Rule L.L.5
A MOVE-like instruction that writes the SR register is not allowed at LPB-2, LPB-1, LPB, LPB+1, or
LPB+2 of a long loop.
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