Freescale Semiconductor SC140 specifications Conditionally Execute a Group or Subgroup Prefix IFc

IFc

IFc	Conditionally Execute a Group or Subgroup (PREFIX) IFc
Operation		Assembler Syntax
If T == 0,	then execute group/subgroup	IFF group or subgroup of instructions
	else treat as NOP
If T == 1,	then execute group/subgroup	IFT group or subgroup of instructions
	else treat as NOP
execute group/subgroup unconditionally		IFA group or subgroup of instructions

Description

These instructions add conditional control over a group or subgroup of instructions in a VLES.

IFF

Execute the group or subgroup if T is equal to zero (condition is false). If T is equal to one (condition is true), the group or subgroup is treated as a NOP. This instruction can be used in conjunction with IFT to form an if/else clause.

IFT

Execute the group or subgroup if T is equal to one (condition is true). If T is equal to zero (condition is false), the group or subgroup is treated as a NOP. This instruction can be used in conjunction with IFF to form an if/else clause.

IFA

Always execute the group or subgroup. This instruction may be used in conjunction with IFT or IFF to split a VLES group into conditional and unconditional subgroups, where IFA must be the last subgroup in the VLES.

The following combinations of these instructions can be used:

IFT	group			; execute group if T is set
IFF	group			; execute group if T is clear
IFA	group			; execute group unconditionally
IFT	subgroup1	IFA	subgroup2	; execute subgroup1 if T is set,
				; execute subgroup2 unconditionally
IFF	subgroup1	IFA	subgroup2	; execute subgroup1 if T is clear,
				; execute subgroup2 unconditionally
IFT	subgroup1	IFF	subgroup2	; execute subgroup1 if T is set,
				; execute subgroup2 if T is clear

Notes: 1. The instructions in the subgroups can be conditional (e.g., TFRT, JF), which adds finer control.

2.The “IFA group” is the same as not using IFc. That is, unconditional execution of the VLES.

3.The detailed use of IFc is defined by Section 7.2, “VLES Grouping Semantics,” and programming rule G.P.7 in Section 7.5.3, “Prefix Grouping Rules.”

A-176 SC140 DSP Core Reference Manual