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8da986ea87
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.
65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
#include "nvim/assert.h"
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#include "nvim/map.h"
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#if !defined(KEY_NAME) || !defined(VAL_NAME)
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// Don't error out. it is nice to type-check the file in isolation, in clangd or otherwise
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# define KEY_NAME(x) x##int
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# define VAL_NAME(x) quasiquote(x, ptr_t)
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#endif
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#define MAP_NAME(x) VAL_NAME(KEY_NAME(x))
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#define MAP_TYPE MAP_NAME(Map_)
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#define KEY_TYPE KEY_NAME()
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#define VALUE_TYPE VAL_NAME()
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#define INITIALIZER VAL_NAME(value_init_)
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VALUE_TYPE *MAP_NAME(map_ref_)(MAP_TYPE *map, KEY_TYPE key, KEY_TYPE **key_alloc)
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{
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uint32_t k = KEY_NAME(mh_get_)(&map->set, key);
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if (k == MH_TOMBSTONE) {
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return NULL;
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}
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if (key_alloc) {
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*key_alloc = &map->set.keys[k];
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}
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return &map->values[k];
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}
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VALUE_TYPE *MAP_NAME(map_put_ref_)(MAP_TYPE *map, KEY_TYPE key, KEY_TYPE **key_alloc,
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bool *new_item)
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{
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MHPutStatus status;
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uint32_t k = KEY_NAME(mh_put_)(&map->set, key, &status);
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if (status != kMHExisting) {
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if (status == kMHNewKeyRealloc) {
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map->values = xrealloc(map->values, map->set.h.keys_capacity * sizeof(VALUE_TYPE));
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}
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map->values[k] = INITIALIZER;
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}
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if (new_item) {
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*new_item = (status != kMHExisting);
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}
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if (key_alloc) {
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*key_alloc = &map->set.keys[k];
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}
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return &map->values[k];
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}
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VALUE_TYPE MAP_NAME(map_del_)(MAP_TYPE *map, KEY_TYPE key, KEY_TYPE *key_alloc)
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{
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VALUE_TYPE rv = INITIALIZER;
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uint32_t k = KEY_NAME(mh_delete_)(&map->set, &key);
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if (k == MH_TOMBSTONE) {
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return rv;
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}
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if (key_alloc) {
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*key_alloc = key;
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}
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rv = map->values[k];
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if (k != map->set.h.n_keys) {
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map->values[k] = map->values[map->set.h.n_keys];
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}
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return rv;
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}
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