testfloat_gen
John R. Hauser
2018 January 20
The testfloat_gen program generates test cases for testing that an
implementation of floating-point arithmetic conforms to the IEEE Standard for
Binary Floating-Point Arithmetic.
testfloat_gen is part of the Berkeley TestFloat package, a small
collection of programs for performing such tests.
For general information about TestFloat, see file
TestFloat-general.html
A single execution of testfloat_gen generates test cases for only
a single floating-point operation and associated options.
The testfloat_gen program must be repeatedly executed to generate
test cases for each operation to be tested.
The testfloat_gen program writes the test cases it generates to
standard output.
This output can either be captured in a file through redirection, or be piped
to another program that exercises a floating-point operation using the test
cases as they are supplied.
Depending on use, the total output from testfloat_gen can be
large, so piping to another program may be the best choice to avoid using
inordinate file space.
The format of testfloat_gen’s output is raw hexadecimal
text, described in the section below titled Output Format.
The testfloat_gen program is executed as a command in one of these
forms:
Square brackets (testfloat_gen [<option>...] <type> testfloat_gen [<option>...] <function>
[ ]) denote optional arguments, and
<option> is a supported option, documented below.
A testfloat_gen command expects either a
<type> specifying the type and number of outputs or a
<function> naming a floating-point operation.
If testfloat_gen is executed without any arguments, a summary of
usage is written.
A <type> can be one of the following:
Optional
ui32unsigned 32-bit integersui64unsigned 64-bit integersi32signed 32-bit integersi64signed 64-bit integersf16 [<num>]one or more 16-bit half-precision floating-point valuesf32 [<num>]one or more 32-bit single-precision floating-point valuesf64 [<num>]one or more 64-bit double-precision floating-point valuesextF80 [<num>]one or more 80-bit double-extended-precision floating-point valuesf128 [<num>]one or more 128-bit quadruple-precision floating-point values
<num> is one of 1, 2, <type> is given without
<num> (such as ui32 or
f64), testfloat_gen outputs a list of values of the
specified type, one value per line, appropriate for testing a floating-point
operation with exactly one operand of the given type.
If a floating-point type and number are given (such as
f32 2extF80 1testfloat_gen
outputs the specified number of values per line, appropriate for testing a
floating-point operation with that number of operands.
Although the exact operation being tested is not specified, the test cases
output by testfloat_gen cover all standard floating-point
operations, to the degree explained in
TestFloat-general.html
If a <function> operation name is given, then each
line of output from testfloat_gen contains not only the operands
for that operation (as would be generated by an appropriate
<type> argument) but also the expected results as
determined by testfloat_gen’s internal floating-point
emulation (Berkeley SoftFloat).
The available operation names are listed in
TestFloat-general.htmltestfloat_gen, this may or may not
indicate an error in the floating-point operation.
For further explanation, see
TestFloat-general.html
The testfloat_gen program accepts several command options.
If mutually contradictory options are given, the last one has priority.
-help
The -help option causes a summary of program usage to be written,
after which the program exits.
-prefix <text>
The -prefix option causes testfloat_gen to write the
supplied text argument verbatim as the first line of output before any test
cases.
This can be used, for example, to indicate to a downstream program what kind of
test to perform for the test cases that follow.
-seed <num>
The -seed option sets the seed for the pseudo-random number
generator used for generating test cases.
The argument to -seed is a nonnegative integer.
Executing the same testfloat_gen program with the same arguments
(including the same pseudo-random number seed) should always generate the same
sequence of test cases, whereas changing the pseudo-random number seed should
result in a different sequence of test cases.
The default seed number
-level <num>
The -level option sets the level of testing.
The argument to -level can be either 1
-n <num>
Option -n specifies the number of test cases to generate.
For each <type> or
<function> and each testing level (set by
-level), there is a minimum value that testfloat_gen
will accept for <num>.
If no -n option is given, the number of test cases generated by
testfloat_gen equals the minimum value acceptable for the
-n argument.
Option -n cannot be used to reduce this number, but can increase
it, without changing the testing level.
-forever
The -forever option causes test cases to be generated
indefinitely, without limit (until the program is terminated by some external
cause).
The testing level is set to 2 by this option.
-precision32, -precision64, -precision80
When a <function> is specified that is an
-precision32 option sets the rounding
precision to -precision64 sets the rounding precision to
-precision80 sets the rounding precision to the full
-precision80.
-rnear_even, -rnear_maxMag, -rminMag, -rmin, -rmax, -rodd
When a <function> is specified that requires
rounding, the -rnear_even option sets the rounding mode to
nearest/even;
-rnear_maxMag sets rounding to nearest/maximum magnitude
(nearest-away);
-rminMag sets rounding to minimum magnitude (toward zero);
-rmin sets rounding to minimum (down, toward negative infinity);
-rmax sets rounding to maximum (up, toward positive infinity);
and -rodd, if supported, sets rounding to odd.
These options are ignored for operations that are exact and thus do not round.
When rounding mode is relevant but not specified, the default is to round to
nearest/even, same as -rnear_even.
-tininessbefore, -tininessafter
When a <function> is specified that requires
rounding, the -tininessbefore option indicates that tininess on
underflow will be detected before rounding, while -tininessafter
indicates that tininess on underflow will be detected after rounding.
These options are ignored for operations that are exact and thus do not round.
When the method of tininess detection matters but is not specified, the default
is to detect tininess on underflow after rounding, same as
-tininessafter.
-notexact, -exact
When a <function> is specified that rounds to an
integer (either conversion to an integer type or a roundToInt
operation), the -notexact option indicates that the inexact
exception flag is never raised, while -exact indicates that the
inexact exception flag is to be raised if the result is inexact.
For other operations, these options are ignored.
If neither option is specified, the default is not to raise the inexact
exception flag when rounding to an integer, same as -notexact.
For each test case generated, testfloat_gen writes a single line
of text to standard output.
When the testfloat_gen command is given a
<type> argument, each test case consists of either
one integer value or one, two, or three floating-point values.
Each value is written to output as a raw hexadecimal number.
When there is more than one value per line, they are separated by spaces.
For example, output from executing
might look like this:testfloat_gen f64 2
with each hexadecimal number being one3F90EB5825D6851E C3E0080080000000 41E3C00000000000 C182024F8AE474A8 7FD80FFFFFFFFFFF 7FEFFFFFFFFFFF80 3FFFED6A25C534BE 3CA1000000020000 ...
3F9 are the sign and encoded exponent of the
When testfloat_gen is given a <function>
operation name, each line of output has not only the operands for the operation
but also the expected output, consisting of a result value and the exception
flags that are raised.
For example, the output from
could include these lines:testfloat_gen f64_add
On each line, the first two numbers are the operands for the floating-point addition, and the third and fourth numbers are the expected floating-point result (the sum) and the exception flags raised. Exception flags are encoded with one bit per flag as follows:3F90EB5825D6851E C3E0080080000000 C3E0080080000000 01 41E3C00000000000 C182024F8AE474A8 41E377F6C1D46E2D 01 7FD80FFFFFFFFFFF 7FEFFFFFFFFFFF80 7FF0000000000000 05 3FFFED6A25C534BE 3CA1000000020000 3FFFED6A25C534BF 01 ...
bit 0 inexact exception bit 1 underflow exception bit 2 overflow exception bit 3 infinite exception (“divide by zero”) bit 4 invalid exception