Motorola DSP56000 manual Start Hardware Loop At LA, Jclr Reset Jset RTI JMP RTS, JSR Wait

INSTRUCTION DESCRIPTIONS

DO	Start Hardware Loop
At LA	any two-word instruction*
	Jcc	REP
	JCLR	RESET
	JSET	RTI
	JMP	RTS
	JScc	STOP
	JSR	WAIT

DO

	*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.
Other Restrictions:	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

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	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

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