Keep in mind that these conversions are approximate and may not always be accurate.
IF Sinhala letter IN voiced_consonants THEN map to unvoiced Tamil counterpart IF Sinhala letter has aspiration THEN remove aspiration IF Sinhala vowel == 'æ' THEN replace with 'a' ELSE map via lookup table sinhala to tamil letters
Vowel mapping is straightforward phonetically, but Sinhala has additional vowels (æ, æː) which have no Tamil equivalent and must be approximated (æ → a or ai). Keep in mind that these conversions are approximate