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Diffstat (limited to 'src/exchangedb/exchange_do_amount_specific.sql')
-rw-r--r-- | src/exchangedb/exchange_do_amount_specific.sql | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/src/exchangedb/exchange_do_amount_specific.sql b/src/exchangedb/exchange_do_amount_specific.sql new file mode 100644 index 000000000..9b305a3ec --- /dev/null +++ b/src/exchangedb/exchange_do_amount_specific.sql @@ -0,0 +1,92 @@ +-- +-- This file is part of TALER +-- Copyright (C) 2014--2022 Taler Systems SA +-- +-- TALER is free software; you can redistribute it and/or modify it under the +-- terms of the GNU General Public License as published by the Free Software +-- Foundation; either version 3, or (at your option) any later version. +-- +-- TALER is distributed in the hope that it will be useful, but WITHOUT ANY +-- WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR +-- A PARTICULAR PURPOSE. See the GNU General Public License for more details. +-- +-- You should have received a copy of the GNU General Public License along with +-- TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/> +-- + +-------------------------------------------------------------- +-- Taler amounts and helper functions +------------------------------------------------------------- + +CREATE OR REPLACE FUNCTION amount_normalize( + IN amount taler_amount + ,OUT normalized taler_amount +) +LANGUAGE plpgsql +AS $$ +BEGIN + normalized.val = amount.val + amount.frac / 100000000; + normalized.frac = amount.frac % 100000000; +END $$; + +COMMENT ON FUNCTION amount_normalize + IS 'Returns the normalized amount by adding to the .val the value of (.frac / 100000000) and removing the modulus 100000000 from .frac.'; + +CREATE OR REPLACE FUNCTION amount_add( + IN a taler_amount + ,IN b taler_amount + ,OUT sum taler_amount +) +LANGUAGE plpgsql +AS $$ +BEGIN + sum = (a.val + b.val, a.frac + b.frac); + CALL amount_normalize(sum ,sum); + + IF (sum.val > (1<<52)) + THEN + RAISE EXCEPTION 'addition overflow'; + END IF; +END $$; + +COMMENT ON FUNCTION amount_add + IS 'Returns the normalized sum of two amounts. It raises an exception when the resulting .val is larger than 2^52'; + +CREATE OR REPLACE FUNCTION amount_left_minus_right( + IN l taler_amount + ,IN r taler_amount + ,OUT diff taler_amount + ,OUT ok BOOLEAN +) +LANGUAGE plpgsql +AS $$ +BEGIN + +IF (l.val > r.val) +THEN + ok = TRUE; + IF (l.frac >= r.frac) + THEN + diff.val = l.val - r.val; + diff.frac = l.frac - r.frac; + ELSE + diff.val = l.val - r.val - 1; + diff.frac = l.frac + 100000000 - r.frac; + END IF; +ELSE + IF (l.val = r.val) AND (l.frac >= r.frac) + THEN + diff.val = 0; + diff.frac = l.frac - r.frac; + ok = TRUE; + ELSE + diff = (-1, -1); + ok = FALSE; + END IF; +END IF; + +RETURN; +END $$; + +COMMENT ON FUNCTION amount_left_minus_right + IS 'Subtracts the right amount from the left and returns the difference and TRUE, if the left amount is larger than the right, or an invalid amount and FALSE otherwise.'; |