09-15-2005
A solution involving portable C eludes me! I naturally rejected the idea of having change() locate its return address on the stack and alter it to step over the i=10 statement. The precise location of the return address and even whether to increment it or decrement it and certainly by how much can vary from system to system. There is really no guarantee that the return address will be stored on the stack or even that there is a stack. I admit that I don't know of any currently marketed unix systems without a stack or that move the PC backwards. But I also don't know of any standard prohibiting them. These days we are in transistion from 32 bit to 64 bit architectures. Most versions of unix currently support executables in either architecture. So the change() function would need to detect the length of the return address as well.
But the other problem that I see with this involves agressive optimization. There is no indication that i is accessible to change() or is otherwise aliased or volatile. So there is no reason that the compiler writer could not legally choose to emit code that operates like...
i=10;
change();
printf("%d",i);
Whether or not that would happen would probably depend on the optimization level selected and the compiler used, and whether or not the resulting executable is intended to interact with a symbolic debugger.
So if you have a portable solution, I would love to see it!
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LEARN ABOUT DEBIAN
freecell-solver-range-parallel-solve
HOOLA(6) Freecell Solver HOOLA(6)
NAME
freecell-solver-range-parallel-solve - The Freecell Solver utility for solving a range of Microsoft Freecell/Freecell Pro Boards
SYNOPSIS
freecell-solver-range-parallel-solve start end print_step [--binary-output-to filename] [--total-iterations-limit limit] [fc-solve
Arguments...]
DESCRIPTION
freecell-solver-range-parallel-solve is a command line application that solves a range of Freecell deals of Microsoft Freecell and Freecell
Pro.
start is the first board to solve; end is the last (inclusive) and print_step is the division of board numbers in which to print a status
message.
Following this three mandatory parameters are several flags specific to the range solve. (refer to the OPTIONS section for more
information)
Afterwards one can give it a fc-solve command line that it will use to solve each board. Refer to the fc-solve(6) man page for information
about its options.
OPTIONS
--total-iterations-limit sets the maximal number of iterations with which to try to solve each deal. After that, the program will give up
and report that the board was intractable.
--binary-output-to sets the filename into which to output the number of iterations it took to solve each board. This file can later be used
with statistical preset optimizers such as those found in the Freecell Solver version control repository.
SEE ALSO
fc-solve(6)
AUTHOR
Shlomi Fish, <http://www.shlomifish.org/> .
Freecell Solver 3.12.0 2012-06-22 HOOLA(6)