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Message-ID: <3C0E3509.7EAF89EF@oculustech.com>
Date: Wed, 05 Dec 2001 06:54:00 -0000
From: Timothy Wall <twall@oculustech.com>
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Organization: Oculus Technologies
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Subject: ARM float/double conversion
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In gdb/doublest.c, there is some conversion done for
floatformat_littlebyte_bigword (currently only used by ARM):

          longswaps = fmt->totalsize / FLOATFORMAT_CHAR_BIT;
          longswaps >>= 3;

          while (longswaps-- > 0)
            {
              /* This is ugly, but efficient */
              *swapout++ = swapin[4];
              *swapout++ = swapin[5];
              *swapout++ = swapin[6];
              *swapout++ = swapin[7];
              *swapout++ = swapin[0];
              *swapout++ = swapin[1];
              *swapout++ = swapin[2];
              *swapout++ = swapin[3];
              swapin += 8;
            }

What's odd is that fmt->totalsize can be either 64 or 96, based on the formats
defined in libiberty/floatformat.c.  For either case, longswaps will be 1, so
I don't understand why
this code was "generalized".  I assume that the extended double on the ARM has
just the
first two 32-bit words swapped.

I actually need to extend this code to do similar swaps for a 32-bit float,
and was going to
"generalize" to accommodate that (little-endian, bigword, word size is 16
bits).

T.