From 8da986ea877b07a5eb117446f410f2a7fc8cd9cb Mon Sep 17 00:00:00 2001 From: bfredl Date: Wed, 13 Sep 2023 13:39:18 +0200 Subject: refactor(grid): change schar_T representation to be more compact Previously, a screen cell would occupy 28+4=32 bytes per cell as we always made space for up to MAX_MCO+1 codepoints in a cell. As an example, even a pretty modest 50*80 screen would consume 50*80*2*32 = 256000, i e a quarter megabyte With the factor of two due to the TUI side buffer, and even more when using msg_grid and/or ext_multigrid. This instead stores a 4-byte union of either: - a valid UTF-8 sequence up to 4 bytes - an escape char which is invalid UTF-8 (0xFF) plus a 24-bit index to a glyph cache This avoids allocating space for huge composed glyphs _upfront_, while still keeping rendering such glyphs reasonably fast (1 hash table lookup + one plain index lookup). If the same large glyphs are using repeatedly on the screen, this is still a net reduction of memory/cache consumption. The only case which really gets worse is if you blast the screen full with crazy emojis and zalgo text and even this case only leads to 4 extra bytes per char. When only <= 4-byte glyphs are used, plus the 4-byte attribute code, i e 8 bytes in total there is a factor of four reduction of memory use. Memory which will be quite hot in cache as the screen buffer is scanned over in win_line() buffer text drawing A slight complication is that the representation depends on host byte order. I've tested this manually by compling and running this in qemu-s390x and it works fine. We might add a qemu based solution to CI at some point. --- src/nvim/api/ui.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'src/nvim/api/ui.c') diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c index 70c97be984..0ea2310042 100644 --- a/src/nvim/api/ui.c +++ b/src/nvim/api/ui.c @@ -833,8 +833,7 @@ void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Int bool was_space = false; for (size_t i = 0; i < ncells; i++) { repeat++; - if (i == ncells - 1 || attrs[i] != attrs[i + 1] - || strcmp(chunk[i], chunk[i + 1]) != 0) { + if (i == ncells - 1 || attrs[i] != attrs[i + 1] || chunk[i] != chunk[i + 1]) { if (UI_BUF_SIZE - BUF_POS(data) < 2 * (1 + 2 + sizeof(schar_T) + 5 + 5) + 1) { // close to overflowing the redraw buffer. finish this event, // flush, and start a new "grid_line" event at the current position. @@ -859,7 +858,9 @@ void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Int uint32_t csize = (repeat > 1) ? 3 : ((attrs[i] != last_hl) ? 2 : 1); nelem++; mpack_array(buf, csize); - mpack_str(buf, chunk[i]); + char sc_buf[MAX_SCHAR_SIZE]; + schar_get(sc_buf, chunk[i]); + mpack_str(buf, sc_buf); if (csize >= 2) { mpack_uint(buf, (uint32_t)attrs[i]); if (csize >= 3) { @@ -869,7 +870,7 @@ void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Int data->ncells_pending += MIN(repeat, 2); last_hl = attrs[i]; repeat = 0; - was_space = strequal(chunk[i], " "); + was_space = chunk[i] == schar_from_ascii(' '); } } // If the last chunk was all spaces, add a clearing chunk even if there are @@ -893,8 +894,10 @@ void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Int for (int i = 0; i < endcol - startcol; i++) { remote_ui_cursor_goto(ui, row, startcol + i); remote_ui_highlight_set(ui, attrs[i]); - remote_ui_put(ui, chunk[i]); - if (utf_ambiguous_width(utf_ptr2char((char *)chunk[i]))) { + char sc_buf[MAX_SCHAR_SIZE]; + schar_get(sc_buf, chunk[i]); + remote_ui_put(ui, sc_buf); + if (utf_ambiguous_width(utf_ptr2char(sc_buf))) { data->client_col = -1; // force cursor update } } -- cgit