mod optimisations

[shramee]

Pull Request type

Optimisations for mod arithmetics.

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Mod operations not as fast as they can be.

Issue Number: N/A

What is the new behavior?

⚠️ div_mod test included here is added in PR #238

DIVISION OPTIMISATION (from core::math functions)
// div_mod_test     BEFORE gas usage est.: 97351914
// div_mod_test     BEFORE gas usage est.: 277900

MINOR optimisations (from inline)
// add_mod_1_test   BEFORE gas usage est.: 163180
// add_mod_1_test   AFTER gas usage est.:  159880
// add_mod_2_test   BEFORE gas usage est.: 109020
// add_mod_2_test   AFTER gas usage est.:  106820
// add_mod_p_test   BEFORE gas usage est.: 433980
// add_mod_p_test   AFTER gas usage est.:  425180
// mult_mod_1_test  BEFORE gas usage est.: 455340
// mult_mod_1_test  AFTER gas usage est.:  444940
// mult_mod_2_test  BEFORE gas usage est.: 455340
// mult_mod_2_test  AFTER gas usage est.:  444940
// mult_mod_test    BEFORE gas usage est.: 455340
// mult_mod_test    AFTER gas usage est.:  444940
// sub_mod_1_test   BEFORE gas usage est.: 330380
// sub_mod_1_test   AFTER gas usage est.:  319980
// sub_mod_2_test   BEFORE gas usage est.: 330380
// sub_mod_2_test   AFTER gas usage est.:  319980
// sub_mod_test     BEFORE gas usage est.: 356100
// sub_mod_test     AFTER gas usage est.:  346300

Does this introduce a breaking change?

• Yes
• No

Other information