Add public decompose operation

[mborland]

Give the user the non normalized representation of the internal value

Closes: #1392

[cppalliance-bot]

An automated preview of the documentation is available at https://1393.decimal.prtest3.cppalliance.org/libs/decimal/doc/html/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-05-18 14:40:54 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.5%. Comparing base (4353200) to head (9afcfbe).
⚠️ Report is 4 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #1393     +/-   ##
=========================================
+ Coverage     98.4%   98.5%   +0.1%     
=========================================
  Files          288     290      +2     
  Lines        22972   23067     +95     
  Branches      1997    1996      -1     
=========================================
+ Hits         22604   22700     +96     
+ Misses         368     367      -1     

Files with missing lines	Coverage Δ
include/boost/decimal/cmath.hpp	100.0% <ø> (ø)
include/boost/decimal/decimal128_t.hpp	95.6% <ø> (ø)
include/boost/decimal/decimal32_t.hpp	95.5% <ø> (ø)
include/boost/decimal/decimal64_t.hpp	94.6% <ø> (ø)
include/boost/decimal/decimal_fast128_t.hpp	96.0% <ø> (ø)
include/boost/decimal/decimal_fast32_t.hpp	97.3% <ø> (ø)
include/boost/decimal/decimal_fast64_t.hpp	97.5% <ø> (ø)
include/boost/decimal/detail/cmath/decompose.hpp	100.0% <100.0%> (ø)
test/test_decompose.cpp	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes

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