pre_mul and cam_mul are in RAW space, these WB multipliers to be applied before color conversion.
rgb_cam is from RAW to 'linear sRGB', so D65.
You can multiply rgb_cam[][] matrix to some adjustment matrix to get other output space (see LibRaw:::convert_to_rgb() source, this function also contains some of correction matrices for Adobe, ProPhoto, WideGamut and XYZ spaces).
pre_mul and cam_mul are in RAW space, these WB multipliers to be applied before color conversion.
rgb_cam is from RAW to 'linear sRGB', so D65.
You can multiply rgb_cam[][] matrix to some adjustment matrix to get other output space (see LibRaw:::convert_to_rgb() source, this function also contains some of correction matrices for Adobe, ProPhoto, WideGamut and XYZ spaces).