On Tue, Jun 14, 2011 at 06:51, jerry DeLisle <jvdeli...@charter.net> wrote: >> It should be easy to implement: >> >> After the switch between F and E editing, we just need to shift the >> decimal point and decrement the exponent. No new rounding is required, >> because we keep the number of significant digits. >> > > OK, after a little bit of experimentation, I have arrived at the updated > patch attached. > > This has been regression tested and passes all test cases I am aware of. I > also have included a new test case gcc/testsuite/gfortran.dg/fmt_g.f90. > > OK for trunk?
I have reviewed your patch, and I noticed that you placed the digit-shifting code quite at the top of output_float(), where the final value of e is not even known. Due to rounding, e can be modified after this point, so your code will generate invalid output in some cases, for example: print "(-2PG0)", nearest(0.1d0, -1.0d0) ! 1.0000000000000000E+001 expected .0099999999999999992E+001 Please put the code where at belongs, after the switch between F and E editing (based on the final value of e). The same applies to the scale factor in general, e.g. print "(-2pg12.3)", 0.096 ! 1.00E+01 expected 0.001E+02 print "(-1pg12.3)", 0.0996 ! 1.00E+00 expected 0.010E+01 print "(-2pg12.3)", 0.09996 ! 1.00E+01 expected 0.100 print "(-1pg12.3)", 0.09996 ! 1.00E+00 expected 0.100 print "(1pg12.3)", 0.099996 ! 1.000E-01 expected 0.100 print "(2pg12.3)", 0.099996 ! 10.00E-02 expected 0.100 print "(-2pg12.3)", 999.6 ! 0.100E+04 expected 0.001E+06 print "(-1pg12.3)", 999.6 ! 0.100E+04 expected 0.010E+05 print "(1pg12.3)", 999.6 ! 0.100E+04 expected 9.996E+02 print "(2pg12.3)", 999.6 ! 0.100E+04 expected 99.96E+01 Please revise your code to fix this. A working approach I have outlined in http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48906#c28 and an (alpha) implementation is here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48906#c31 Thomas
