For primary sources, I've always thought
Rangācārya, M. (Ed.) The Gaṇita-sāra-sangraha of Mahāvīrācārya with English Translation and Notes Madras Govt. Press, 1912,
to be a brilliantly clear exposition of medieval Indian mathematics.
For a general introduction and orientation, with up-to-date notes and bibliography for further reading, we now have
Plofker, K. Mathematics in India Princeton University Press, 2009.