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<H1>Berkeley TestFloat Release 3: <CODE>testsoftfloat</CODE></H1>

<P>
John R. Hauser<BR>
2014 Dec 17<BR>
</P>


<H2>Overview</H2>

<P>
The <CODE>testsoftfloat</CODE> program tests that a build of the Berkeley
SoftFloat library conforms to the IEEE Standard for Binary Floating-Point
Arithmetic as expected.
Program <CODE>testsoftfloat</CODE> is part of the Berkeley TestFloat package, a
small collection of programs for performing such tests.
For general information about TestFloat, as well as for basics about the
operation of <CODE>testsoftfloat</CODE> and how to interpret its output, see
file
<A HREF="TestFloat-general.html"><NOBR><CODE>TestFloat-general.html</CODE></NOBR></A>.
</P>

<P>
Note that, even if there are no bugs in the source code for SoftFloat (not
guaranteed), a build of SoftFloat might still fail due to an issue with the
build process, such as an incompatible compiler option or a compiler bug.
</P>

<P>
The <CODE>testsoftfloat</CODE> program will ordinarily test a function for all
rounding modes defined by the IEEE Floating-Point Standard, one after the
other.
If an operation is not supposed to require rounding, it will by default be
tested only with the rounding mode set to <CODE>near_even</CODE>
(nearest/even).
In the same way, if an operation is affected by the way in which underflow
tininess is detected, <CODE>testsoftfloat</CODE> tests the function with
tininess detected both before rounding and after rounding.
For <NOBR>80-bit</NOBR> double-extended-precision operations affected by
rounding precision control, <CODE>testsoftfloat</CODE> also tests the function
for all three rounding precision modes, one after the other.
Testing can be limited to a single rounding mode, a single tininess mode,
and/or a single rounding precision with appropriate command-line options.
</P>


<H2>Command Syntax</H2>

<P>
The <CODE>testsoftfloat</CODE> program is executed as a command with this
syntax:
<BLOCKQUOTE>
<PRE>
testsoftfloat [&lt;option&gt;...] &lt;function&gt;
</PRE>
</BLOCKQUOTE>
Square brackets (<CODE>[ ]</CODE>) denote optional arguments,
<CODE>&lt;option&gt;</CODE> is a supported option, and
<CODE>&lt;function&gt;</CODE> is the name of either a testable function or a
function set.
The available options and function sets are documented below.
If <CODE>testsoftfloat</CODE> is executed without any arguments, a summary of
usage is written.
</P>


<H2>Options</H2>

<P>
The <CODE>testsoftfloat</CODE> program accepts several command options.
If mutually contradictory options are given, the last one has priority.
</P>

<H3><CODE>-help</CODE></H3>

<P>
The <CODE>-help</CODE> option causes a summary of program usage to be written,
after which the program exits.
</P>

<H3><CODE>-level &lt;num&gt;</CODE></H3>

<P>
The <CODE>-level</CODE> option sets the level of testing.
The argument to <CODE>-level</CODE> can be either 1 <NOBR>or 2</NOBR>.
The default is <NOBR>level 1</NOBR>.
Level 2 performs many more tests than <NOBR>level 1</NOBR> and thus can reveal
bugs not found by <NOBR>level 1</NOBR>.
</P>

<H3><CODE>-errors &lt;num&gt;</CODE></H3>

<P>
The <CODE>-errors</CODE> option instructs <CODE>testsoftfloat</CODE> to report
no more than the specified number of errors for any combination of function,
rounding mode, etc.
The argument to <CODE>-errors</CODE> must be a nonnegative decimal integer.
Once the specified number of error reports has been generated,
<CODE>testsoftfloat</CODE> ends the current test and begins the next one, if
any.
The default is <NOBR><CODE>-errors</CODE> <CODE>20</CODE></NOBR>.
</P>

<P>
Against intuition, <NOBR><CODE>-errors</CODE> <CODE>0</CODE></NOBR> causes
<CODE>testsoftfloat</CODE> to report every error it finds.
</P>

<H3><CODE>-errorstop</CODE></H3>

<P>
The <CODE>-errorstop</CODE> option causes the program to exit after the first
function for which any errors are reported.
</P>

<H3><CODE>-forever</CODE></H3>

<P>
The <CODE>-forever</CODE> option causes a single function to be repeatedly
tested.
Only one rounding mode and/or rounding precision can be tested in a single
execution.
If not specified, the rounding mode defaults to nearest/even.
For <NOBR>80-bit</NOBR> double-extended-precision functions, the rounding
precision defaults to full double-extended precision.
The testing level is set to 2 by this option.
</P>

<H3><CODE>-precision32, -precision64, -precision80</CODE></H3>

<P>
For <NOBR>80-bit</NOBR> double-extended-precision funcions affected by
rounding precision control, the <CODE>-precision32</CODE> option restricts
testing to only the cases in which the rounding precision is
<NOBR>32 bits</NOBR>, equivalent to <NOBR>32-bit</NOBR> single-precision.
The other rounding precision choices are not tested.
Likewise, <CODE>-precision64</CODE> fixes the rounding precision to
<NOBR>64 bits</NOBR>, equivalent to <NOBR>64-bit</NOBR> double-precision;
and <CODE>-precision80</CODE> fixes the rounding precision to the full
<NOBR>80 bits</NOBR> of the double-extended-precision format.
All these options are ignored for operations not affected by rounding precision
control.
</P>

<H3><CODE>-rnear_even, -rnear_maxMag, -rminMag, -rmin, -rmax</CODE></H3>

<P>
The <CODE>-rnear_even</CODE> option restricts testing to only the cases in
which the rounding mode is nearest/even.
The other rounding mode choices are not tested.
Likewise, <CODE>-rnear_maxMag</CODE> forces rounding to nearest/maximum
magnitude (nearest-away), <CODE>-rminMag</CODE> forces rounding to minimum
magnitude (toward zero), <CODE>-rmin</CODE> forces rounding to minimum (down,
toward negative infinity), and <CODE>-rmax</CODE> forces rounding to maximum
(up, toward positive infinity).
These options are ignored for operations that are exact and thus do not round.
</P>

<H3><CODE>-tininessbefore, -tininessafter</CODE></H3>

<P>
The <CODE>-tininessbefore</CODE> option restricts testing to only the cases in
which tininess on underflow is detected before rounding.
Likewise, <CODE>-tininessafter</CODE> restricts testing to only the cases in
which tininess on underflow is detected after rounding.
</P>

<H3><CODE>-notexact, -exact</CODE></H3>

<P>
For functions that round to an integer (conversions to integer types and the
<CODE>roundToInt</CODE> functions), the <CODE>-notexact</CODE> option restricts
testing to only the cases for which the <CODE><I>exact</I></CODE> operand
(specifying whether the <I>inexact</I> exception flag may be raised) is
<CODE>false</CODE>.
Likewise, the <CODE>-exact</CODE> option restricts testing to only the cases
for which the <CODE><I>exact</I></CODE> operand is <CODE>true</CODE>.
</P>


<H2>Function Sets</H2>

<P>
Just as <CODE>testsoftfloat</CODE> can test a function for all five rounding
modes in sequence, multiple functions can be tested with a single execution of
<CODE>testsoftfloat</CODE>.
Two sets are recognized:  <CODE>-all1</CODE> and <CODE>-all2</CODE>.
The set <CODE>-all1</CODE> comprises all one-operand operations, while
<CODE>-all2</CODE> is all two-operand operations.
A function set is used in place of a function name in the
<CODE>testsoftfloat</CODE> command line, such as
<BLOCKQUOTE>
<PRE>
testsoftfloat [&lt;option&gt;...] -all1
</PRE>
</BLOCKQUOTE>
</P>

<P>
For the purpose of deciding the number of operands of an operation, any
<CODE><I>roundingMode</I></CODE> and <CODE><I>exact</I></CODE> arguments are
ignored.
(Such arguments specify the rounding mode and whether the <I>inexact</I>
exception flag may be raised, respectively.)
Thus, functions that convert to integer type and the <CODE>roundToInt</CODE>
functions are included in the set of one-operand operations tested by
<CODE>-all1</CODE>.
</P>


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