Freescale Semiconductor SC140 specifications Status Bit Rules, Rule D.8, Rule D.9, Rule T.1

Models: SC140

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Static Programming Rules

Rule D.8

A MOVE-like instruction that reads the SR register is not allowed in the delay slot of a CONTD instruction.

Example 7-37. SR Read in a CONTD Delay Slot

contd _label

;not allowed

move.l sr,d0

Rule D.9

Instructions that read the EMR register are not allowed in the delay slot of a RTED, or RTSTKD instruction.

Example 7-38. EMR Use in Return Delay Slots

rtstkd

;not allowed

move.l emr,d0

rted

bmclr #$fffb,emr.l ;not allowed

7.5.6 Status Bit Rules

Rule T.1

At least one VLES is required between an instruction that affects the T status bit in SR and an AGU instruction in an IFT/IFF group or subgroup. This rule does not apply to AGU instructions in an IFA subgroup.

Example 7-39. T Bit Update to IFT/IFF AGU Use

tsteq d0

 

; not allowed

ift move.l r0,d1

 

tsteq d0

 

 

nop

 

; allowed

ift move.l r0,d1

 

tsteq d0

 

; allowed

ift mac d0,d1,d2

 

tsteq d0

ifa move.l r0,d1

; allowed

ift mac d0,d1,d2

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SC140 DSP Core Reference Manual

Page 272
Image 272
Freescale Semiconductor SC140 specifications Status Bit Rules, Rule D.8, Rule D.9, Rule T.1