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                                SoftFloat

This provides a software implementation of functions performing floating point 
operations according to the IEEE 754 standard.

It is used in or1ksim due to problems arising when using the simulator host 
machine's floating point unit to perform single precision floating point
calculations (or even double, in some cases.) Typically the host machine's FPU
will support extended (80-bit), or higher, precision, resulting in values which
can differ from those which are calculated on a true single or double precision
floating point unit (very small differences when in rounding and generating
status flags.)

Although using a software implementation is slow, it ensures an accurate 
simulation of a single or double precision floating point unit.

This software was sourced from the author's (John Hauser) site:

http://www.jhauser.us/arithmetic/SoftFloat.html

Note that the code cannot be compiled with -O0 for debugging purpose, because
of the approach used to code inlining. Additional macros have been added to
ease this problem. For debugging purposes, Or1ksim should be configured adding
CFLAGS="-O0 -DINLINE=static -DNO_SOFTFLOAT_UNUSED" to the configure line.

Julius Baxter, August 1, 2010
Jeremy Bennett, August 4, 2010 (-O0 compilation)