Function test_extract_window

bitvm/src/bigint/std.rs:965–1000

()

    // test the extract window fn
    #[test]
    fn test_extract_window() {
        let mut prng = ChaCha20Rng::seed_from_u64(8);

        for _ in 0..100 {
            // generate random start_index and window
            let start_index = prng.gen_range(1..=31);
            let window = prng.gen_range(1..=start_index);

            // generate a random u32
            let random_u32: u32 = prng.gen();

            // compute the values by shifting
            let initial_limb = random_u32 >> (32u32 - start_index);
            let expected_window = initial_limb >> (start_index - window);
            let modified_limb = if start_index == window {
                0
            } else {
                (initial_limb << (32u32 - start_index + window)) >> (32u32 - start_index + window)
            };

            let script = script!(
                {initial_limb}

                {extract_digits(start_index,window)}

                {modified_limb}
                OP_EQUALVERIFY

                {expected_window}
                OP_EQUAL
            );

            let res = crate::execute_script(script.clone());
            assert!(res.success);
        }
    }

    // manual test of transform to and from U256.
    #[test]