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Restore SNAPSHOT version.

1.2.x mergewithmaster

One-hot-encode the cycle number, so that the trial remainder doesn't
depend on the output of a decoder.  For a single-precision divider, this
increases the FF count from 100 to 122, but for a moderate frequency
target, it's roughly area-neutral and leaks less.

Bump build.sbt for next release.

Might do this for other HardFloat modules over time, but this is the one
I need for the time being.

Bump for 1.2-20191106-SNAPSHOT.

Bump master SNAPSHOT version.

Sometimes using the RawFloat version directly is more useful.

For example, when converting from uint128 to float32 (whose max exponent
is 2^127), the unit fails to detect overflow for numbers just under 2^128.

The bug only manifests when the ranges are that close.  If the float has
greater range, or has much smaller range, the bug does not manifest.

Existing RV32 and RV64 cores are unaffected by this bug, because no such
conversions exist in the ISA.

* Update testing infrastructure from chisel 2 to 3.

This requires updates to the test harness, as well as to the driver. Use
verilator for tests. Tests run but are currently failing and I'm not
sure why.

* Use strtoull instead of strtoll

* Fix incorrect outputs

* added detailed algorithm used for sqrt

* fixed wording

* added explanation for division

This reverts commit ca89a808.

See this discussion for an explanation: https://github.com/ucb-bar/berkeley-hardfloat/pull/28

SoftFloat/TestFloat Release 3e.  First, the rounding mode code for 'odd'
rounding is changed from 5 to 6.  Second, conversions to integer now round
to the nearest odd integer instead of rounding to minimum magnitude.

* add small div/sqrt unit

* Chisel3 doesn't permit mixed UInt/SInt muxing/assignment

* Fix control bug in DivSqrtRecFN_small

After an uncommon-case operation, outValid would remain high until
another inValid was presented, instead of going low after one cycle.

integers.

'RoundAnyRawFNToRecFN'.

integer values in module 'DivSqrtRecF64_mulAddZ31'.