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Discussion Groups | TMS320C54x | Re: An Important problem about C54x data types (extended precision)

Technical discussions about the TI C54x DSPs (including the c5401, c5402, c5402a, c5404, c5407, c5409, c5409a, c5410, c5410a, c5416, c5420, c5421, c5441, c549, c5470 and c5471).

  

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Re: An Important problem about C54x data types (extended precision) - Jeff Brower - May 18 15:18:30 2008



Ahmad-

> 1- Would you know how we can perform 40-bit operations like add or
> multiply in C54x which its longest data tyype is 32 bit?
> In MELPe 1200bps there is some functions which does 40-bit
> operation do you know how can I implement them for C54x?

Here are some docs that should help:

  http://focus.ti.com/lit/an/spra297/spra297.pdf

  http://focus.ti.com/lit/ug/spru173/spru173.pdf

  http://focus.ti.com/lit/an/spra554b/spra554b.pdf

The first doc is a good one, even though it's about C62xx and not C54x.  It explains
how to use a series of 16-bit multiplies to achieve 32-bit and 64-bit results.  The
graphics in the explanation are excellent.

In the second doc, look for section 6.4, Extended Precision Arithmetic.

> 2- if I want to define a big array in assembly I should write its
> type (for example .int or .word) at the first of each line. How
> can I do it if the number of lines in my array were high?

The question doesn't seem clear.  Do you mean like this:

  int ahmad_array[N] = {

    5764, 5782, 6975, 6370, 5389,
    7926, 6939, 7332, 8027, 8468,
    ...
    ...

    }

The above array definition can be as big as you want.  If you want the array to be
loaded into program memory (re. one of your previous questions), then use:

  const int ahmad_array[N] = {

-Jeff

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