[GRASS-dev] [bug #4864] (grass) integer division errors

[Glynn Clements]

Request Tracker wrote:

> this bug's URL: http://intevation.de/rt/webrt?serial_num=4864

> Subject: integer division errors
> 
> Hi,
> 
> I've just fixed a bug in the symbol library where:
> 
> float_red = int_red / 255;
> 
> int/int -> int, so the answer was always 0.0 or 1.0. no good.
> 
> grep finds these ones too, maybe some are wrong, some are ok?

They're all okay.

> display/d.his/his.c:            R = R * I / 255;
> display/d.his/his.c:            G = G * I / 255;
> display/d.his/his.c:            B = B * I / 255;
> display/d.his/his.c:            R = 127 + (R - 127) * S / 255 ;
> display/d.his/his.c:            G = 127 + (G - 127) * S / 255 ;
> display/d.his/his.c:            B = 127 + (B - 127) * S / 255 ;
> general/g.pnmcomp/main.c:           *r = (*r * c0 + *p * c1) / 255;
> raster/r.his/his.c:             R = R * I / 255;
> raster/r.his/his.c:             G = G * I / 255;
> raster/r.his/his.c:             B = B * I / 255;
> raster/r.his/his.c:             R = 127 + (R - 127) * S / 255 ;
> raster/r.his/his.c:             G = 127 + (G - 127) * S / 255 ;
> raster/r.his/his.c:             B = 127 + (B - 127) * S / 255 ;
> raster3d/r3.showdspf/togif.c:           val = (nshades*k)/255;
> raster/r.out.tiff/r.out.tiff.c:#define  SCALE(x)        (((x)*((1L<<16)-1))/255)

These are all supposed to produce integer results.

> raster/r.out.vtk/writeascii.c:   fprintf(fp, "%lf %lf %lf \n", r / 255, g / 255, b / 255);
> raster3d/r3.out.vtk/writeVTKData.c:    fprintf(fp, "%.*f ", dp, (value / 255));
> raster3d/r3.out.vtk/writeVTKData.c:    fprintf(fp, "%.*f ", dp, (value / 255));

These all have FP numerators.

-- 
Glynn Clements <glynn at gclements.plus.com>