Re: Math accelerator in native library

Walter Fetter Lages wrote:

>     Hello!
>
>     Has anybody used the math accelarator (32/16 bit mult and div) in 
> a native method?
>
>     Can it be used in native methods? 

Yes.

>
>
>     If so, math accelerator SFRs (MA, MB, MC) needs to be preserved 
> across native method invocation? 

The registers do not have to be preserved BUT you do have to enclose 
your entire accelerator access code block in a critical section. This 
will prevent your code from scrogging operations being performed in 
another process.

Example:
  TINIOS_ENTER_CRITICAL_SECTION
  mov   MCNT1, #10h               ; reset coprocessor
  mov   Ma, R0                          ; load operand A
  mov   Ma, R1                          ;
  mov   Ma, R2                          ;
  mov   Ma, R3                          ;
  mov   Mb, R0_B1                   ; load operand B
  mov   Mb, R1_B1                   ;
  db    0,0,0,0,0,0,0,0,0             ; inject NOPs to wait for result
  mov   R3, Ma                          ; unload results
  mov   R2, Ma                          ;
  mov   R1, Ma                          ;
  mov   R0, Ma                          ;
  mov   R1_B1, Mb                   ;
  mov   R0_B1, Mb                   ;
  TINIOS_EXIT_CRITICAL_SECTION



-- 
Thomas Chenot


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