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TMS320F28335: pipeline using RPT instruction

Paolo Benini
Intellectual 485 points

Hi all,

I'm trying to optimize some assembly routines and wondering how the pipeline would look like using RPT instructions.

To be more precise, here is a part of an assembly routine with a pipeline diagram (which should be right in my understanding):

 

Instr. Ops. Address Opcode Instruction #
MOVL XAR7, ACC 0x008DAB 1EA7 I1
MOVL XAR6, XAR4 0x008DAC C4A4 I2
DEC AR5 0x008DAD 0BA5 I3
ZAPA 0x008DAE 5633 I4
RPT AR5 0x008DAF F7A5 I5
||MINL ACC, *XAR4++ 0x008DB0 56500084 I6

 

PIPELINE              
               
F1 F2 D1 D2 R1 R2 E W CPU Cycles
0x008DAB               1
0x008DAC 1EA7 1EA7           2
  0BA5:C4A4 C4A4 XAR7 = ACC         3
0x008DAE   0BA5 XAR6 = XAR4 -       4
  F7A5:5633 5633 AR5 = AR5 - 1 - -     5
0x008DB0   F7A5 ACC = 0, P = 0, OVC = 0 - - -   6
  56500084 56500084 RPTC = AR5 - - - - 7
      Generate source address - - - - 8
        Drive address - - - 9
          Read data pointed to by XAR4 - - 10
            ACC = MIN(ACC, [XAR4]) - 11

What happens at the next execution of MINL instruction?

Many thanks.

Paolo

  • 0
    TI__Guru* 91235 points

    Paolo Benini said:

    What happens at the next execution of MINL instruction?

    Many thanks.

    MINL will be pushed back through the pipeline at D2 immediately behind the previous MINL.  There is no re-fetch associated with RPT.

    Regards,

    Lori