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#include "memory.h"
#include "pack.h"
#include "plat.h"
#include "str.h"
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#define pack_max_files 4
typedef struct Pack_File {
FILE* handle;
Pack_Entry* entry;
int offset;
} Pack_File;
Pack_Entry* get_pack_table(Pack* p) {
return (Pack_Entry*)(
(char*)&p[1] + pack_max_files * sizeof(Pack_File)
);
}
int get_pack_size(int entry_count) {
return sizeof(Pack) +
pack_max_files * sizeof(Pack_File) +
entry_count * sizeof(Pack_Entry);
}
Pack_Entry* pack_find_entry(Pack* p, const char* name) {
Pack_Entry* tab = get_pack_table(p);
uint32_t hash = hash_string(name);
int idx = (int)(hash % p->file_count), i;
int e = (int)p->file_count;
for (i = 0; i < e; i++) {
Pack_Entry* e = &tab[idx];
if (!e->name[0] || string_equal(name, e->name))
return e;
idx = (int)((idx + 1) % p->file_count);
}
return 0;
}
static void insert_entry(Pack* p, const Pack_Entry* e) {
Pack_Entry* d = pack_find_entry(p, e->name);
assert(d != 0);
if (d->name[0])
print_war("Duplicate entry in %s: %s\n", p->filename, e->name);
*d = *e;
}
static void read_table(Pack* p, FILE* f) {
uint32_t i, e = p->file_count;
Pack_Entry* tab = get_pack_table(p);
for (i = 0; i < e; i++)
tab[i].name[0] = 0;
for (i = 0; i < e; i++) {
Pack_Entry e;
fread(&e, sizeof e, 1, f);
insert_entry(p, &e);
}
}
static void init_files(Pack* p) {
int i;
Pack_File* files = (Pack_File*)&p[1];
for (i = 0; i < pack_max_files; i++) {
files[i].handle = 0;
}
}
Pack* pack_open(const char* filename, Arena* a) {
Pack* p;
char magic[4];
uint32_t entry_count;
FILE* f = fopen(filename, "rb");
if (!f) return 0;
fread(magic, 1, 4, f);
if (
magic[0] != 'P' ||
magic[1] != 'A' ||
magic[2] != 'C' ||
magic[3] != 'K'
) {
fclose(f);
return 0;
}
fread(&entry_count, 4, 1, f);
p = arena_alloc(a, get_pack_size(entry_count));
p->filename = dup_string(a, filename);
p->file_count = entry_count;
init_files(p);
read_table(p, f);
fclose(f);
return p;
}
void pack_close(Pack* p) {
(void)p;
}
Pack_Entry* pack_get_entry(Pack* p, const char* name) {
Pack_Entry* e = pack_find_entry(p, name);
if (!e || e->name[0] == 0) return 0;
return e;
}
static Pack_File* init_handle(
Pack* p,
Pack_File* h,
const char* name
) {
FILE* f;
Pack_Entry* e = pack_find_entry(p, name);
if (!e || !e->name[0]) return 0;
f = fopen(p->filename, "rb");
if (!f) return 0;
h->offset = 0;
h->handle = f;
h->entry = e;
return h;
}
Pack_File* pack_open_file(Pack* p, const char* name) {
int i;
Pack_File* files = (Pack_File*)&p[1];
for (i = 0; i < pack_max_files; i++) {
Pack_File* file = &files[i];
if (!file->handle)
return init_handle(p, file, name);
}
return 0;
}
void pack_close_file(Pack_File* f) {
fclose(f->handle);
f->handle = 0;
}
int pack_read(Pack_File* f, void* buf, int size) {
int diff = (f->offset + size) - f->entry->size;
int read;
if (diff > 0) size -= diff;
fseek(f->handle, f->entry->offset + f->offset, SEEK_SET);
read = fread(buf, 1, size, f->handle);
f->offset += read;
return read;
}
void pack_seek(Pack_File* f, int offset, Seek_Rel rel) {
switch (rel) {
case seek_rel_cur:
f->offset += offset;
break;
case seek_rel_start:
f->offset = offset;
break;
case seek_rel_end:
f->offset = f->entry->size - offset;
break;
}
}
int pack_tell(Pack_File* f) {
return f->offset;
}
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