From: Sheheryar Qazi <sherry1.sherry1@gmail.com>
To: gcc-help@gcc.gnu.org
Subject: Changing Mantissa's Width in Non-IEEE Floating Point implementation
Date: Thu, 11 Sep 2014 01:31:00 -0000 [thread overview]
Message-ID: <CAH6n9wxarW74RO=R7XqvPDhpxd6F84OQPh9Magt8oRw-xx-BDg@mail.gmail.com> (raw)
Hi,
I have a gcc cross compiler on an 18 bit soft-core processor target
that has the following datatypes defined:
Integer 18 bit, Long 36 bit and float 36-bit(single precision).
Right now my focus is on floating point operation. Since the width is
non-standard(36 bit), I have the following scheme: 27 bits for
Mantissa(significand), 8 bits for Exponents and 1 Sign bit.
I can see the widths are defined in the float.h file. of interest to
me are the following:
FLT_MANT_DIG and FLT_DIG.
They are defined as:
FLT_MANT_DIG 24
FLT_DIG 6
I have changed them to
FLT_MANT_DIG 28
FLT_DIG 9
As per my requirements in float.h and then build the gcc compiler. But
still I get 32 bit floating point output.Do anyone has any experience
implementing non-standard single precision floating point numbers
and/or know wat changes are needed please let me know.
Sincerely
Sheheryar
reply other threads:[~2014-09-11 1:31 UTC|newest]
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