Freescale Semiconductor SC140 specifications Lpmark Programming Guidelines, General Looping Rules

Models: SC140

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LPMARK Rules

LPMARK Rule L.C.11 + L.C.12

A delayed COF instruction is not allowed at LPA-1 or LPB-1 of a loop.

Example 7-102. Delay Slot at LPA or LPB of a Loop

jmpd_dest

;not allowed

nop

{lpmarkb set}

nop

 

nop

 

jmpd _dest

;not allowed

nop

{lpmarka set}

7.8.3.6 General Looping Rules

LPMARK Rule L.G.3 + L.G.4

At least one VLES is required between a MOVE-like instruction that reads the SR register and LPA or LPB of a loop.

Example 7-103. SR Read to LPA or LPB of a Loop

dosetup1 label1 doen1 #5

label1

inc d1

;not allowed

move.l sr,d0

inc d2

{lpmarkb set}

move.l #mem_l1,r1

move.l #mem_l2,r0

doensh0 #$10

;not allowed

push sr

inc d0

{lpmarka set}

7.8.3.7 Rule Detection Across Exception Boundaries

LPMARK Rule SR.6

LPA or LPB cannot be the first two VLES of an exception service routine.

7.8.4 LPMARK Programming Guidelines

The rules in this section cannot be detected by the simulator from its execution trace. The following rules must be detected by the programmer, and can be avoided by good programming practices.

SC140 DSP Core Reference Manual

7-59

Page 309
Image 309
Freescale Semiconductor SC140 specifications Lpmark Programming Guidelines, General Looping Rules