Freescale Semiconductor SC140 specifications LPMARKx End-of-Loop Mark Prefix LPMARKx Operation

Models: SC140

1 760
Download 760 pages 48.94 Kb
Page 535
Image 535

LPMARKx

LPMARKx End-of-Loop Mark (PREFIX) LPMARKx

Operation

 

 

Disassembler Syntax Only

If LCn > 1,

then SAn → PC

LPMARKB (long loop)

 

LCn – 1 → LCn

 

 

else next PC → PC

 

 

0

→ LCn

 

 

0

→ LFn

 

If LCn > 1,

then SAn → PC

LPMARKA (external of nested loops)

 

LCn – 1 → LCn

 

 

else next PC → PC

 

 

0

→ LCn

 

 

0

→ LFn

 

If LCn > 1,

then SAn → PC

LPMARKB (short loop of 2 sets)

 

LCn – 1 → LCn

 

 

else next PC → PC

 

 

0

→ LCn

 

 

0

→ LFn

 

 

0 → SLF

 

If LCn > 1,

then SAn → PC

LPMARKA (short loop of 1 set)

 

LCn – 1 → LCn

 

 

else next PC → PC

 

 

0

→ LCn

 

 

0

→ LFn

 

0 → SLF

Description

The LPMARK prefix bits are used for hardware loops and perform the operations associated with ending a loop iteration: a conditional jump to the start of the loop (based on the value of LCn) and a decrement of LCn. In the case where LCn indicates the last iteration, these bits disable the active loop and do not jump. The LPMARK bits use the SAn/LCn register of the active loop as specified by the LF bits in SR.

The LPMARK bits are encoded in the prefix words, and are not independent instructions. They are generated automatically by the assembler at the correct positions based on the LOOPSTART and LOOPEND assembly directives inserted by the programmer. The assembler does not allow the programmer to use LPMARKx.

SC140 DSP Core Reference Manual

A-221

Page 535
Image 535
Freescale Semiconductor SC140 specifications LPMARKx End-of-Loop Mark Prefix LPMARKx Operation, If LCn Then SAn → PC