v0.8.7 "Signs" - Performance optimizations

This release focuses on performance improvements and bug fixes for issues reported by users and contributors.

Features

• Long array operations such as matrix multiplications can now be interrupted with the EXIT key.

• Eliminate local names from LNAME output. For example, if you perform a sum with a variable named i as an index, no longer report i as being a name used by the expression..

• Implement HEAD and TAIL for text objects.

• Allow constant definitions to contain expressions, which will be fully evaluated when using the →Num. This makes it possible now define constants using other constants, in the spirit of the more recent CODATA recommandations.

• Library management commands Attach, Detach and Libs are now implemented. These commands make it possible to reload a library entry after changing its definition on disk. While they take arguments that are similar to what HP calculators do, they are not interpreting them in the same way due to hardware differences between SwissMicros and HP calculators.

Bug fixes

• Fix hard crash when running some RPL programs using conditional loops, local variables and/or deep recursion. The crash was caused by a non-robust check of whether the call stack needed to grow or shrink, which was replaced with a much more robust check.

• Fixed the precedence of the unary - operator, so that -X^2 now parses correctly (it used to be interpretd as (-X)^2)

• Fix a crash where an error during an array operation could cause a null pointer to be pushed on the stack.

• The test suite now correctly reports error detected while checking the examples in the online help.

• The multi-solver no longer considers the index variable in a sum or product as a variable to solve for. This avoids spurious errors claiming that a solution cannot be found. The same also applies other functions that take a variable name as an argument, such as Root, Integrate or Isolate.

• Fix a crash when comparing unit objects that cannot be converted from one to the other, e.g. comparing 1_m and 1_h.

• Fix the order of commands in the build instructions for Windows.

• Fix the NDupN command to duplicate an object N times. In earlier releases, it was incorrectly duplicating N objects and leaving N on the stack.

• Accept addition and subtraction between a number and a unit object where the unit can be reduced to a number, so that '1+1_km/m' is now a valid expression. A few additional entries in the equation library now work thanks to that fix.

• Avoid a rare crash where the error command would be corrupted when cleaning temporaries.

Improvements

• Performance optimizations for decimal arithmetic, using 25x25 matrix multiplication as a test scenario to optimize. The performance of such multiplication was improved by about one order of magnitude, and is now comparable to DM42 performance. This was achieved in particular by making more aggressive cleanup of temporaries, by reducing the need for garbage collection, by adding a fast-tracked path for arithmetic operations when the types are the same as for the last operation, and by deferring the construction of arrays until the value of all elements are computed.

• Add a few new sanity checks for the runtime when running on the simulator, notably to detect cases where the internal pointers are not in the expected order, and to more precisely report issues if integrity checks fail during garbage collection

• Add locking to the garbage collected pointers list when running on the simulator, in order to improve test stability. Testing on the simulator is the one case where multiple threads may concurently access the pointers list.

• Accelerate the tests that insert large amounts of text from source code, notably the equation parsing tests and the help examples checks. In addition, use a smarter method to insert RPL separators such as [] or '', taking advantage of the fact that they are usually entered in pairs. These two improvements reduce the total runtime of the entire test suite by a factor of more than 4.

• While testing the online help examples, only report the exact section title and not all the section titles that contain the same
  text.

• Systematically strip tags and assignment objects for all arithmetic operations.

• Add a version of the debug_printf that automatically selects where to draw on the screen, and automatically clear what follows the printed text using a gray pattern.

• Render the DB48x TrueType font to bitmap using a more recent version of the FreeType library. This causes minor glyph differences compared to earlier releases. The test suite was adjusted accordingly.

• Remove some of the leftover references to newRPL commands that will not be implemented or make no sense for DB48x. This work is not finished yet. The mechanism to remember which command caused a particular error was also made somewhat more efficient.

• Consolidate the two distinct documentations of the Root command.