Motorola DSP56000 Manual page 360

24-bit digital signal processor
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DO
At LA
Other Restrictions:
A DO instruction cannot be repeated using the REP instruction.
Note: Due to instruction pipelining, if an AGU register (Mn, Nn, or Rn) is directly changed
with a MOVE-type instruction, the new contents may not be available for use until the
second following instruction. See the restrictions discussed in A.9.6 - R, N, and M Regis-
ter Restrictions on page A-310.This restriction also applies to the situation in which the
last instruction in a DO loop changes an address register and the first instruction at the
top of the DO loop uses that same address register. The top instruction becomes the fol-
lowing instruction because of the loop construct.
Similarly, since the DO instruction accesses the program controller registers, the DO
instruction must not be immediately preceded by any of the following instructions:
Immediately before DO
MOTOROLA
INSTRUCTION DESCRIPTIONS
Start Hardware Loop
any two-word instruction*
Jcc
JCLR
JSET
JMP
JScc
JSR
*This restriction applies to the situation in which the
DSP56K simulator's single-line assembler is used to
change the last instruction in a DO loop from a one-
word instruction to a two-word instruction.
DO SSH,xxxx
JSR to (LA) whenever the loop flag (LF) is set
JScc to (LA) whenever the loop flag (LF) is set
JSCLR to (LA) whenever the loop flag (LF) is set
JSSET to (LA) whenever the loop flag (LF) is set
MOVEC to LA, LC, SSH, SSL, or SP
MOVEM to LA, LC, SSH, SSL, or SP
MOVEP to LA, LC, SSH, SSL, or SP
MOVEC from SSH
MOVEM from SSH
MOVEP from SSH
INSTRUCTION SET DETAILS
DO
REP
RESET
RTI
RTS
STOP
WAIT
A - 91

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