(
&mut self,
mut iter: I,
offset: usize,
)
| 719 | /// Callers must ensure that `iter` reports an exact size via `size_hint`. |
| 720 | #[inline] |
| 721 | pub unsafe fn extend_bool_trusted_len<I: Iterator<Item = bool>>( |
| 722 | &mut self, |
| 723 | mut iter: I, |
| 724 | offset: usize, |
| 725 | ) { |
| 726 | let (lower, upper) = iter.size_hint(); |
| 727 | let len = upper.expect("Iterator must have exact size_hint"); |
| 728 | assert_eq!(lower, len, "Iterator must have exact size_hint"); |
| 729 | debug_assert!( |
| 730 | offset <= self.len * 8, |
| 731 | "offset must be <= buffer length in bits" |
| 732 | ); |
| 733 | |
| 734 | if len == 0 { |
| 735 | return; |
| 736 | } |
| 737 | |
| 738 | let start_len = offset; |
| 739 | let end_bit = start_len + len; |
| 740 | |
| 741 | // SAFETY: we will initialize all newly exposed bytes before they are read |
| 742 | let new_len_bytes = bit_util::ceil(end_bit, 8); |
| 743 | if new_len_bytes > self.len { |
| 744 | self.reserve(new_len_bytes - self.len); |
| 745 | // SAFETY: caller will initialize all newly exposed bytes before they are read |
| 746 | unsafe { self.set_len(new_len_bytes) }; |
| 747 | } |
| 748 | |
| 749 | let slice = self.as_slice_mut(); |
| 750 | |
| 751 | let mut bit_idx = start_len; |
| 752 | |
| 753 | // ---- Unaligned prefix: advance to the next 64-bit boundary ---- |
| 754 | let misalignment = bit_idx & 63; |
| 755 | let prefix_bits = if misalignment == 0 { |
| 756 | 0 |
| 757 | } else { |
| 758 | (64 - misalignment).min(end_bit - bit_idx) |
| 759 | }; |
| 760 | |
| 761 | if prefix_bits != 0 { |
| 762 | let byte_start = bit_idx / 8; |
| 763 | let byte_end = bit_util::ceil(bit_idx + prefix_bits, 8); |
| 764 | let bit_offset = bit_idx % 8; |
| 765 | |
| 766 | // Clear any newly-visible bits in the existing partial byte |
| 767 | if bit_offset != 0 { |
| 768 | let keep_mask = (1u8 << bit_offset).wrapping_sub(1); |
| 769 | slice[byte_start] &= keep_mask; |
| 770 | } |
| 771 | |
| 772 | // Zero any new bytes we will partially fill in this prefix |
| 773 | let zero_from = if bit_offset == 0 { |
| 774 | byte_start |
| 775 | } else { |
| 776 | byte_start + 1 |
| 777 | }; |
| 778 | if byte_end > zero_from { |
no test coverage detected