fix value bit corruption

New benchmarks

test node::redeem::benches::decode_fixed_program          ... bench:      47,575.83 ns/iter (+/- 1,888.92)
test value::benches::bench_value_create_512_256           ... bench:      62,040.00 ns/iter (+/- 684.18)
test value::benches::bench_value_create_512_256_compact   ... bench:       3,091.83 ns/iter (+/- 19.26)
test value::benches::bench_value_create_512_256_padded    ... bench:       3,034.38 ns/iter (+/- 17.38)
test value::benches::bench_value_create_64k               ... bench:     671,748.75 ns/iter (+/- 4,494.75)
test value::benches::bench_value_create_64k_compact       ... bench:      32,111.70 ns/iter (+/- 5,517.22)
test value::benches::bench_value_create_64k_padded        ... bench:      32,177.62 ns/iter (+/- 7,199.71)
test value::benches::bench_value_create_deep_some         ... bench:     401,901.88 ns/iter (+/- 4,945.75)
test value::benches::bench_value_create_deep_some_compact ... bench:     145,748.00 ns/iter (+/- 833.20)
test value::benches::bench_value_create_deep_some_padded  ... bench:       1,205.44 ns/iter (+/- 5.89)
test value::benches::bench_value_create_u2048             ... bench:     482,537.50 ns/iter (+/- 8,726.38)
test value::benches::bench_value_create_u2048_compact     ... bench:       2,169.61 ns/iter (+/- 7.86)
test value::benches::bench_value_create_u2048_padded      ... bench:       2,075.53 ns/iter (+/- 16.34)
test value::benches::bench_value_create_u64               ... bench:          32.03 ns/iter (+/- 0.91)
test value::benches::bench_value_create_u64_compact       ... bench:         162.57 ns/iter (+/- 1.75)
test value::benches::bench_value_create_u64_padded        ... bench:         113.74 ns/iter (+/- 0.67)
test value::benches::bench_value_display_512_256          ... bench:      74,847.14 ns/iter (+/- 1,099.57)
test value::benches::bench_value_display_64k              ... bench:     709,160.00 ns/iter (+/- 12,038.00)
test value::benches::bench_value_display_deep_some        ... bench:      43,401.18 ns/iter (+/- 559.59)
test value::benches::bench_value_display_u2024            ... bench:      44,913.00 ns/iter (+/- 477.15)
test value::benches::bench_value_display_u64              ... bench:         357.24 ns/iter (+/- 7.69)

Author: stringhandler

src/value.rs

@@ -276,14 +276,19 @@ fn right_shift_1(inner: &Arc<[u8]>, bit_offset: usize, new_bit: bool) -> (Arc<[u
     // If the current bit offset is nonzero this is super easy: we just
     // lower the bit offset and call that a fix.
     if bit_offset > 0 {
-        if new_bit {
-            let new_bit_offset = bit_offset - 1;
+        let new_bit_offset = bit_offset - 1;
+        let mask = 1u8 << (7 - new_bit_offset % 8);
+        let current_bit = inner[new_bit_offset / 8] & mask != 0;
+        if current_bit == new_bit {
+            (Arc::clone(inner), new_bit_offset)
+        } else if new_bit {
             let mut bx: Box<[u8]> = inner.as_ref().into();
-            bx[new_bit_offset / 8] |= 1 << (7 - new_bit_offset % 8);
+            bx[new_bit_offset / 8] |= mask;
             (bx.into(), new_bit_offset)
         } else {
-            // ...and if we are inserting a 0 we don't even need to allocate a new [u8]
-            (Arc::clone(inner), bit_offset - 1)
+            let mut bx: Box<[u8]> = inner.as_ref().into();
+            bx[new_bit_offset / 8] &= !mask;
+            (bx.into(), new_bit_offset)
         }
     } else {
         // If the current bit offset is 0, we just shift everything right by 8