pub fn block_major_patch_index(
patch_row: usize,
patch_col: usize,
grid_w: usize,
merge: usize,
) -> usizeExpand description
2026-09-25: Index of the patch at (patch_row, patch_col) in the
2×2-block-major stream the GLM tower expects.
((h_block * w_blocks + w_block) * merge + row_in_block) * merge + col_in_block. The tower’s 2×2 downsample folds four consecutive tokens
into one block, which is correct only in this order.