Freescale Semiconductor SC140 Rule G.P.1, Example 7-16 Vles Extension Words Exceed Two

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Static Programming Rules

Rule G.P.1

Up to two extension words can be grouped in a VLES. This means:

A three-word instruction can only be grouped in a VLES with one-word instructions.

Example 7-16 VLES Extension Words Exceed Two

[

; 1st extension word

bmset #$ab34,d3.l

move.l #$f0d0,vba

; not allowed - 2nd & 3rd extension word

]

 

A two-word instruction can only be grouped in a VLES with one other two-word instruction and/or one-word instructions.

Example 7-17 Two-Word Instructions Exceed Two

[

; 1st extension word

move.f #$1234,d0

extract #8,#16,d0,d2

; 2nd extension word

extractu #8,#24,d0,d3

; not allowed - 3rd extension word

zxt.b d0,d0

 

]

 

The second and third words of an instruction are called “extension words.” An extension word can occur in the following cases:

Some immediate values

Some absolute addresses or offsets

Bit mask instructions listed in Table A-16: Prefix Instructions on page A-18

INSERT or EXTRACT/U instructions

Integer double precision instructions such as IMACxx, IMACxxxx, IMPYxx, IMPYxxxx and

IMPY.W

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SC140 DSP Core Reference Manual

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Freescale Semiconductor SC140 specifications Rule G.P.1, Example 7-16 Vles Extension Words Exceed Two