term: cache tile attrs in COL_BUF's spare stride bytes (3.5x scroll)

term_write_tilemap's attribute pass ran color_setup - the full Fano
palette walk - for all 360 tiles on every scroll. render_tile already
computes the attr when a tile changes, so store it (COL_BUF + slot*64
+ ACACHE + tcol; the stride's 24 spare bytes were free) and the attr
pass becomes a table read. update_cursor_attr reads the cache too.
term_init now redraws before writing the tilemap so the cache is warm.

Measured entry-to-return with the emulator cycle counter, ANSI test
screen content: term_write_tilemap 723k -> 114k T-cycles (6.3x),
term_scroll 857k -> 248k (3.5x) - a scroll drops from ~12 frames of
guest CPU to ~3.5.

0 files changed, 0 insertions, 0 deletions