/*
** $Id$
** load bytecodes from files
** See Copyright Notice in lua.h
*/

#include "engine/lua/lauxlib.h"
#include "engine/lua/lfunc.h"
#include "engine/lua/lmem.h"
#include "engine/lua/lstring.h"
#include "engine/lua/lundump.h"

#define	LoadBlock(b,size, Z)	ezread(Z, b, size)
#define	LoadNative(t, Z)		LoadBlock(&t, sizeof(t), Z)
#define doLoadNumber(f, Z)		f = LoadNumber(Z)

static float conv_float(const char *data) {
	const byte *udata = (const byte *)(data);
	byte fdata[4];
	fdata[0] = udata[3];
	fdata[1] = udata[2];
	fdata[2] = udata[1];
	fdata[3] = udata[0];
	return *(const float *)(fdata);
}

static void unexpectedEOZ(ZIO *Z) {
	luaL_verror("unexpected end of file in %s", zname(Z));
}

static int32 ezgetc(ZIO *Z) {
	int32 c = zgetc(Z);
	if (c == EOZ)
		unexpectedEOZ(Z);
	return c;
}

static void ezread(ZIO *Z, void *b, int32 n) {
	int32 r = zread(Z, b, n);
	if (r)
		unexpectedEOZ(Z);
}

static uint16 LoadWord(ZIO *Z) {
	uint16 hi = ezgetc(Z);
	uint16 lo = ezgetc(Z);
	return (hi << 8) | lo;
}

static uint32 LoadLong(ZIO *Z) {
	uint32 hi = LoadWord(Z);
	uint32 lo = LoadWord(Z);
	return (hi << 16) | lo;
}

static float LoadFloat(ZIO *Z) {
	uint32 l = LoadLong(Z);
	return conv_float((const char *)&l);
}

static byte *LoadCode(ZIO *Z) {
	int32 size = LoadLong(Z);
	int32 s = size;
	void* b;
	if (s != size)
		luaL_verror("code too long (%ld bytes) in %s", size, zname(Z));
	b = luaM_malloc(size);
	LoadBlock(b, size, Z);
	return (byte *)b;
}

static TaggedString *LoadTString(ZIO *Z) {
	int32 size = LoadWord(Z);
	int32 i;

	if (size == 0)
		return NULL;
	else {
		char *s = luaL_openspace(size);
		LoadBlock(s, size, Z);
		for (i = 0; i < size; i++)
			s[i] ^= 0xff;
		return luaS_newlstr(s, size - 1);
	}
}

static void LoadLocals(TProtoFunc *tf, ZIO *Z) {
	int32 i, n = LoadWord(Z);
	if (n == 0)
		return;
	tf->locvars = luaM_newvector(n + 1, LocVar);
	for (i = 0; i < n; i++) {
		tf->locvars[i].line = LoadWord(Z);
		tf->locvars[i].varname = LoadTString(Z);
	}
	tf->locvars[i].line = -1;		// flag end of vector
	tf->locvars[i].varname = NULL;
}

static TProtoFunc *LoadFunction(ZIO *Z);

static void LoadConstants(TProtoFunc *tf, ZIO *Z) {
	int32 i, n = LoadWord(Z);
	tf->nconsts = n;
	if (n == 0)
		return;
	tf->consts = luaM_newvector(n, TObject);
	for (i = 0; i < n; i++) {
		TObject *o = tf->consts + i;
		ttype(o) = (lua_Type)-ezgetc(Z);
		switch ((uint32)ttype(o)) {
		case (uint32)-'N':
			ttype(o) = LUA_T_NUMBER;
		case (uint32)LUA_T_NUMBER:
			doLoadNumber(nvalue(o), Z);
			break;
		case (uint32)-'S':
			ttype(o) = LUA_T_STRING;
		case (uint32)LUA_T_STRING:
			tsvalue(o) = LoadTString(Z);
			break;
		case (uint32)-'F':
			ttype(o) = LUA_T_PROTO;
		case (uint32)LUA_T_PROTO:
			break;
		case (uint32)LUA_T_NIL:
			break;
		default:
			luaL_verror("bad constant #%d in %s: type=%d [%s]", i, zname(Z), ttype(o), luaO_typename(o));
			break;
		}
	}
}

static void LoadSubfunctions(TProtoFunc *tf, ZIO *Z) {
	char t;
	do {
		t = ezgetc(Z);
		switch (t) {
		case '#':
			{
				int32 i = LoadWord(Z);
				if (ttype(tf->consts + i) != LUA_T_PROTO)
					luaL_verror("trying to load function into nonfunction constant (type=%d)", ttype(tf->consts + i));
				tfvalue(tf->consts + i) = LoadFunction(Z);
				break;
			}
		case '$':
			break;
		default:
			luaL_verror("invalid subfunction type %c", t);
		}
	} while (t != '$');
}

static TProtoFunc *LoadFunction(ZIO *Z) {
	TProtoFunc *tf = luaF_newproto();
	tf->lineDefined = LoadWord(Z);
	tf->fileName = LoadTString(Z);
	tf->code = LoadCode(Z);
	LoadConstants(tf, Z);
	LoadLocals(tf, Z);
	LoadSubfunctions(tf, Z);

	return tf;
}

static void LoadSignature(ZIO *Z) {
	const char *s = SIGNATURE;

	while (*s && ezgetc(Z) == *s)
		++s;
	if (*s)
		luaL_verror("bad signature in %s", zname(Z));
}

static void LoadHeader(ZIO *Z) {
	int32 version, id, sizeofR;
#if 0
	real f = (real)-TEST_NUMBER;
	real tf = (real)TEST_NUMBER;
#endif
	LoadSignature(Z);
	version = ezgetc(Z);
	if (version > VERSION)
		luaL_verror("%s too new: version=0x%02x; expected at most 0x%02x", zname(Z), version, VERSION);
	if (version < VERSION0)			// check last major change
		luaL_verror("%s too old: version=0x%02x; expected at least 0x%02x", zname(Z), version, VERSION0);
	sizeofR = ezgetc(Z);			// test number representation
	id = ezgetc(Z);
	if (id != ID_NUMBER || sizeofR != sizeof(real)) {
		luaL_verror("unknown number signature in %s: read 0x%02x%02x; expected 0x%02x%02x", 
				zname(Z), id, sizeofR, ID_NUMBER, sizeof(real));
	}
#if 0
	doLoadNumber(f, Z);
	if (f != tf) // LUA_NUMBER
		luaL_verror("unknown number representation in %s: read " NUMBER_FMT "; expected " NUMBER_FMT, zname(Z), f, tf);
#endif
	ezgetc(Z);
	ezgetc(Z);
	ezgetc(Z);
}

static TProtoFunc *LoadChunk(ZIO *Z) {
	LoadHeader(Z);
	return LoadFunction(Z);
}

/*
** load one chunk from a file or buffer
** return main if ok and NULL at EOF
*/
TProtoFunc *luaU_undump1(ZIO *Z) {
	int32 c = zgetc(Z);
	if (c == ID_CHUNK)
		return LoadChunk(Z);
	else if (c != EOZ)
		luaL_verror("%s is not a Lua binary file", zname(Z));
	return NULL;
}