Freescale Semiconductor SC140 Example, 2-w prefix + 2 grouped instruction words, aaa =

		DSP Core Instruction Set
Example:
	skipl _last	;(there is a skipl to _last in the program)
	.
	.
	.
	execution_set
_last	execution_set
	execution_setlpmarkA

In the case of the loop having just one execution, the lpmarkA bit is set in the prefix of this single execution set of the loop.

A.1.5.2 Two-Word Prefix

Includes information on grouping, looping, IFc (conditional execution), and high-register banks (D8-D15, R8-R15).

Instruction Formats and Opcodes

Prefix	Words Cycles Type
2W PREFIX	2	0	4

Opcode

15					8	7	0
0	0	1	1	a a	a 0	H t h p j c c c
1	0	1	b	B e	E T	b B e E b B e E

Note: The order of the register bank encoding fields is, for example, E1 E2 E3, with E1 occupying the most significant bit position in the table.

Instruction Fields

aaa:	Number of instruction words being grouped, including the prefix word minus one (for
	example, 2-w prefix + 2 grouped instruction words, aaa = 3).
	For a 2-w prefix at the beginning of the execution set, aaa = 000 and aaa = 001 are reserved as
	escape codes to signify that more prefix words are concatenated to support architectures with 3
	or more prefix words. Use of a 2-w prefix in the middle of the set is reserved for future
	encoding (such as accelerator or predication instructions) and should not be placed as a NOP.
ccc:	Conditional execution of the entire execution set.
	In the following table, true/false relates to the state of the T bit in SR. D0, D1, D2, and D3 are
	DALU instructions, A0 and A1 are AGU or BMU instructions. The numbers relate to the
	relative offset of the instruction from the beginning of the set.
	000—Unconditionally executed
	001—If true (D0, D2, A0), if false (D1, D3, A1)
	010—If true, all the set
	011—If false, all the set
	100—Reserved
	101—Reserved
	110—If true (D0, D2, A0), always (D1, D3, A1)
	111—If false (D0, D2, A0), always (D1, D3, A1)
p:	lpmarkB bit
	In the case of a loop with three or more execution sets, the lpmarkB bit is a one in the
	execution set that is two before the last execution set in the loop.

SC140 DSP Core Reference Manual A-9