Using r.mapcalculator in Python console?

Question

I'm trying to use the r.mapcalculator algorithim in a python script, but I'm having problems in using the r.mapcalculator to tranform a raster layer with float values into integers.

Using the processing toolbox of QGIS, the algorithm works flawlessly. However, using the python code below, the values don't get rounded, instead, I only get NaN values.

processing.runalg("grass:r.mapcalculator","D:/OneDrive/reclassified maps/teste.tif", None, None, None, None, None, "round(A)", None, None, "D:/OneDrive/reclassified maps/teste_arredondado.tif")

EDIT: Just solved the problem. The last None parameters cannot be "None". So, for the GRASS_REGION_PARAMETER I used the extent() comand to create a string.

ext = teste.extent()
a = str(ext.xMinimum())
b = str(ext.xMaximum())
c = str(ext.yMinimum())
d = str(ext.yMaximum())
size = a + ',' + b + ',' + c + ',' + d

The last parameter (GRASS_REGION_CELLSIZE_PARAMETER) just input 0. The final form is

processing.runalg("grass:r.mapcalculator", 
teste, None, None, None, None, None, 
"round(A)", size, '0', 
"D:/OneDrive/Doutoramento/GIS/Aveiro Coelho (2005)/reclassified maps/teste_arredondado.tif")

Answer 1

Examining the content of the file .../.qgis2/processing/processing.log after running the processing toolbox command gives you the result:

ALGORITHM|Fri Jan 09 2015   
18:18:40|processing.runalg("grass:r.mapcalculator","/Users/mytiff.tiff",None,None,None,None,None,"round(A)","202086.577,205625.414407,88411.048,90534.3504441",0,"/Users/mytiffr.tiff")

And if you read Using processing algorithms from the console, you can get help with:

import processing
processing.alghelp("grass:r.mapcalculator")
ALGORITHM: r.mapcalculator - Calculate new raster map from a r.mapcalc expression.
amap <parameters>
bmap <parameters>
cmap <parameters>
dmap <parameters>
emap <parameters>
fmap <parameters>
formula <parameters>
GRASS_REGION_PARAMETER <parameters>
GRASS_REGION_CELLSIZE_PARAMETER <parameters>
outfile <outputs>

In your formula, there is no GRASS_REGION_PARAMETER nor GRASS_REGION_CELLSIZE_PARAMETER, fundamental in GRASS GIS (GRASS GIS: r.mapcalc)