3 files changed, 210 insertions, 2 deletions

diff --git a/qstd/Makefile b/qstd/Makefile
index 3c4b6a8..c4b088b 100644
--- a/qstd/Makefile
+++ b/qstd/Makefile
@@ -5,7 +5,7 @@ defines = -Dplat_x86 -Dplat_posix -Dallocation_default_alignment=8
 cflags = -std=c90 -pedantic -Wall -Wextra $(DEBUG_COMPILE_FLAG) $(includes) $(defines)
 lflags = $(DEBUG_LINK_FLAG)
 
-objects = plat.o memory.o str.o
+objects = plat.o memory.o str.o pack.o
 
 .PHONY: all clean
 
@@ -17,9 +17,12 @@ memory.o: memory.c memory.h plat.h
 plat.o: plat.c plat.h
 	$(CC) -c $(cflags) plat.c -o plat.o
 
-str.o: str.c str.h
+str.o: str.c str.h memory.h
 	$(CC) -c $(cflags) str.c -o str.o
 
+pack.o: pack.c pack.h str.h plat.h memory.h
+	$(CC) -c $(cflags) pack.c -o pack.o
+
 $(target): $(objects)
 	$(AR) -rcs $(target) $(objects)
 
diff --git a/qstd/pack.c b/qstd/pack.c
new file mode 100644
index 0000000..e9ca0c3
--- /dev/null
+++ b/qstd/pack.c
@@ -0,0 +1,165 @@
+#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);
+}
+
+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;
+}
diff --git a/qstd/pack.h b/qstd/pack.h
new file mode 100644
index 0000000..447cd5b
--- /dev/null
+++ b/qstd/pack.h
@@ -0,0 +1,40 @@
+#ifndef pack_h
+#define pack_h
+
+#include <stdint.h>
+
+struct Arena;
+struct Pack_File;
+
+typedef struct {
+	char name[56];
+	uint32_t offset;
+	uint32_t size;
+} Pack_Entry;
+
+typedef struct Pack {
+	char* filename;
+	uint32_t file_count;
+} Pack;
+
+Pack_Entry* pack_find_entry(Pack* p, const char* name);
+Pack_Entry* get_pack_table(Pack* p);
+int get_pack_size(int entry_count);
+
+Pack* pack_open(const char* filename, struct Arena* a);
+void pack_close(Pack* p);
+Pack_Entry* pack_get_entry(Pack* p, const char* name);
+
+typedef enum {
+	seek_rel_cur,
+	seek_rel_start,
+	seek_rel_end
+} Seek_Rel;
+
+struct Pack_File* pack_open_file(Pack* p, const char* name);
+void pack_close_file(struct Pack_File* h);
+int pack_read(struct Pack_File* f, void* buf, int size);
+void pack_seek(struct Pack_File* f, int offset, Seek_Rel rel);
+int pack_tell(struct Pack_File* f);
+
+#endif