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/msgpack_rpc/unpacker.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'src/nvim/msgpack_rpc') diff --git a/src/nvim/msgpack_rpc/unpacker.c b/src/nvim/msgpack_rpc/unpacker.c index c3b1022db2..37e32729cc 100644 --- a/src/nvim/msgpack_rpc/unpacker.c +++ b/src/nvim/msgpack_rpc/unpacker.c @@ -9,6 +9,7 @@ #include "mpack/conv.h" #include "nvim/api/private/helpers.h" #include "nvim/ascii.h" +#include "nvim/grid.h" #include "nvim/macros.h" #include "nvim/memory.h" #include "nvim/msgpack_rpc/channel_defs.h" @@ -497,13 +498,13 @@ redo: if (g->icell == g->ncells - 1 && cellsize == 1 && cellbuf[0] == ' ' && repeat > 1) { g->clear_width = repeat; } else { + schar_T sc = schar_from_buf(cellbuf, cellsize); for (int r = 0; r < repeat; r++) { if (g->coloff >= (int)grid_line_buf_size) { p->state = -1; return false; } - memcpy(grid_line_buf_char[g->coloff], cellbuf, cellsize); - grid_line_buf_char[g->coloff][cellsize] = NUL; + grid_line_buf_char[g->coloff] = sc; grid_line_buf_attr[g->coloff++] = g->cur_attr; } } -- cgit