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good progress on maps

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This commit is contained in:
Ivar Fatland
2026-04-12 10:51:01 +02:00
parent 6aa10199a5
commit 83d66aaf36
4 changed files with 102 additions and 56 deletions
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map.c
+68 -32
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@@ -1,29 +1,29 @@
#include "cig.h"
#include <assert.h>
#define FREE (-1)
#define GRAVESTONE (-2)
#define FLAG_FREE (-1)
#define FLAG_GRAVESTONE (-2)
static inline int mapping_cap(int capacity) {
static inline unsigned int mapping_cap(unsigned int capacity) {
return capacity * 2;
}
typedef struct internal_map_sizes {
int bytes;
int cap_of_items_arr;
int real_cap_of_items_arr;
} internal_map_sizes_t;
internal_map_sizes_t internal_map_sizes(int capacity, int itemsize) {
internal_map_sizes_t internal_map_sizes(unsigned int capacity, unsigned int item_size) {
const size_t cap_of_index_arr =
sizeof(int) * mapping_cap(capacity);
const size_t INC = ALIGN_OF(int);
const size_t SIZE = itemsize * capacity;
const size_t SIZE = item_size * capacity;
const size_t cap_of_items_arr = (SIZE + INC - 1) / INC;
const size_t bytes =
sizeof(map_header_t) + cap_of_items_arr + cap_of_index_arr;
return (internal_map_sizes_t){
.bytes=bytes,
.cap_of_items_arr=cap_of_items_arr,
.real_cap_of_items_arr=cap_of_items_arr,
};
}
@@ -32,7 +32,7 @@ void *map_create_func(
) {
internal_map_sizes_t sizes = internal_map_sizes(
args.initial_capacity,
args.itemsize
args.item_size
);
map_header_t *header =
allocator_alloc_func(
@@ -44,16 +44,16 @@ void *map_create_func(
header->n_items = 0;
header->capacity = args.initial_capacity;
header->itemsize = args.itemsize;
header->keysize = args.keysize;
header->item_size = args.item_size;
header->key_size = args.key_size;
header->allocator = args.allocator;
header->hash = args.hash;
header->equals = args.equals;
header->mapping_arr = (int*) &header->bytes[sizes.cap_of_items_arr];
header->mapping_arr = (int*) &header->bytes[sizes.real_cap_of_items_arr];
header->mapping_capacity = mapping_cap(args.initial_capacity);
for ( int i = 0; i < header->mapping_capacity; i++ ) {
header->mapping_arr[i] = -1;
header->mapping_arr[i] = FLAG_FREE;
}
return header->bytes;
@@ -61,30 +61,42 @@ void *map_create_func(
void *map_grow_func(void *this, const char *file, int line) {
map_header_t *header = PTR_FROM_FIELD_PTR(map_header_t, bytes, this);
int new_size = header->n_items + 1;
int new_n_items = header->n_items + 1;
if (header->capacity < new_size) {
if (header->capacity < new_n_items) {
allocator_t allocator = header->allocator;
int new_capacity = 1;
unsigned int new_capacity = 1;
if (header->capacity > 0) {
new_capacity = header->capacity * 2;
}
internal_map_sizes_t new_size = internal_map_sizes(
new_capacity,
header->itemsize
header->item_size
);
header = allocator_resize_func(allocator, header, new_size.bytes, file, line);
header->mapping_arr = (int*) &header->bytes[new_size.real_cap_of_items_arr];
header->mapping_capacity = mapping_cap(new_capacity);
header->capacity=new_capacity;
static_assert(0, "Overwrite the mapping arr with -1, then iterate"
"through the items arr and find the hashes of the values to populate the"
"mappings");
static_assert(0, "make sure the mapping_arr field is set to the new and"
"correct pointer!");
// first we have to clear the entire mapping array
for ( unsigned int i = 0; i < header->mapping_capacity; i++ ) {
header->mapping_arr[i] = FLAG_FREE;
}
// Then we have to re-hash and map all the items in the existing map.
// The reason for re-hashing is that all hashes are moduloed by the
// size of the mapping array, so the resulting hash will likely change.
for ( unsigned int i = 0; i < header->n_items; i++ ) {
void *pair = &this[i*header->item_size];
// TODO: make the map_pair_hash more private? would be nice to just
// pass in the header, and I don't really think it is needed
// directly by the user of the library.
unsigned int mapping_index = map_pair_hash(this, pair);
header->mapping_arr[mapping_index] = i;
}
}
header->n_items = new_size;
header->n_items = new_n_items;
return header->bytes;
}
@@ -103,12 +115,12 @@ void map_shrink_func(void *this, const char *file, int line) {
static_assert(0, "Hash the key at the removed item to find it in the mapping array, and set it to the gravestone value.");
}
static inline uint32_t fnv_1a(const uint8_t *bytes, const int length) {
uint32_t fnv_1a(const uint8_t *bytes, const unsigned int size) {
// Yanked from: https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
const uint32_t PRIME = 0x01000193;
const uint32_t OFFSET = 0x811c9dc5;
uint32_t hash = OFFSET;
for (int i = 0; i < length; i++) {
for (int i = 0; i < size; i++) {
uint32_t byte = (uint32_t)bytes[i];
hash = hash ^ byte;
hash = hash * PRIME;
@@ -116,12 +128,36 @@ static inline uint32_t fnv_1a(const uint8_t *bytes, const int length) {
return hash;
}
unsigned int map_hash(void *this, void *value) {
static void *internal_cig_key_ptr_from_pair_ptr(void *this, void *pair) {
map_header_t *header = PTR_FROM_FIELD_PTR(map_header_t, bytes, this);
if (header->hash) {
return header->hash(value);
return &pair[header->key_offset];
}
// TODO: just make these internal probably
bool map_pair_key_equals(void *this, void *pair1, void *pair2) {
}
unsigned int map_pair_hash(void *this, void *pair) {
map_header_t *header = PTR_FROM_FIELD_PTR(map_header_t, bytes, this);
void *key = internal_cig_key_ptr_from_pair_ptr(this, pair);
// find the initial index based on hash
uint32_t index;
if (header->hash != NULL) {
index = header->hash(key) % header->mapping_capacity;
} else {
index = fnv_1a(key, header->key_size) % header->mapping_capacity;
}
return (unsigned int) fnv_1a(value, header->keysize) % header->mapping_capacity;
int existing_index = header->mapping_arr[index];
while (!(existing_index == FLAG_FREE || existing_index == FLAG_GRAVESTONE)) {
index = fnv_1a(
(const uint8_t *) &index,
sizeof(index)
) % header->mapping_capacity;
int existing_index = header->mapping_arr[index];
}
return (unsigned int) index;
}
int map_len(void *this) {
@@ -140,6 +176,6 @@ int map_cap(void *this) {
return header->capacity;
}
#undef FREE
#undef GRAVESTONE
#undef FLAG_FREE
#undef FLAG_GRAVESTONE