lua和C交互, 以数组传递参数, 自测成功

C代码: 参考 第28章

//-------- Array Begin --------------------------------------------------------------------
//C语言不允许大小为0的数组，这个1只是一个占位符, newarray 中重新给数组分配空间
typedef struct NumArray {
	size_t size;
	double values[1];
} NumArray;

static NumArray *checkarray (lua_State *L) {
	void *ud = luaL_checkudata(L, 1, "LuaBook.array");
	luaL_argcheck(L, ud != NULL, 1, "`array' expected");
	return (NumArray *)ud;
}

static double *getelem (lua_State *L) {
	NumArray *a = checkarray(L);
	int index = luaL_checkint(L, 2);
	luaL_argcheck(L, 1 <= index && index <= a->size, 2, "index out of range");
	/* return element address */
	return &a->values[index - 1];
}

static int newarray (lua_State *L) {
	int n = luaL_checkint(L, 1);
	//由于原始的结构中已经包含了一个元素的空间, 因此实际分配时从n中减去1
	size_t nbytes = sizeof(NumArray) + (n - 1)*sizeof(double);
	NumArray *a = (NumArray *)lua_newuserdata(L, nbytes);

	luaL_getmetatable(L, "LuaBook.array");
  lua_setmetatable(L, -2);
	a->size = n;

	return 1;  /* new userdatum is already on the stack */
}

static int setarray (lua_State *L) {
#if 0
	NumArray *a = (NumArray *)lua_touserdata(L, 1);
	int index = luaL_checkint(L, 2);
	double value = luaL_checknumber(L, 3);

	luaL_argcheck(L, a != NULL, 1, "`array' expected");
	luaL_argcheck(L, 1 <= index && index <= a->size, 2, "index out of range");
	a->values[index-1] = value;

#else
	double newvalue = luaL_checknumber(L, 3);
  *getelem(L) = newvalue;
#endif

	return 0;
}

static int getarray (lua_State *L) {
#if 0
	NumArray *a = (NumArray *)lua_touserdata(L, 1);
	int index = luaL_checkint(L, 2);
	luaL_argcheck(L, a != NULL, 1, "'array' expected");
	luaL_argcheck(L, 1 <= index && index <= a->size, 2, "index out of range");
	lua_pushnumber(L, a->values[index-1]);

#else
	lua_pushnumber(L, *getelem(L));
#endif

	return 1;
}

static int getsize (lua_State *L) {
#if 0
	NumArray *a = (NumArray *)lua_touserdata(L, 1);
	luaL_argcheck(L, a != NULL, 1, "`array' expected");

#else
	NumArray *a = checkarray(L);
#endif

	lua_pushnumber(L, a->size);

	return 1;
}

static const struct luaL_reg arraylib [] = {
    {"new", newarray},
    {"set", setarray},
    {"get", getarray},
    {"size", getsize},
    {NULL, NULL}
};

int luaopen_array (lua_State *L) {
	luaL_newmetatable(L, "LuaBook.array");
  luaL_openlib(L, "array", arraylib, 0);

  //用传统的 a[] 来操作数组,
  /* now the stack has the metatable at index 1 and 'array' at index 2 */
  lua_pushstring(L, "__index");
  lua_pushstring(L, "get");
  lua_gettable(L, 2); /* get array.get */
  lua_settable(L, 1); /* metatable.__index = array.get */

  lua_pushstring(L, "__newindex");
  lua_pushstring(L, "set");
  lua_gettable(L, 2); /* get array.set */
  lua_settable(L, 1); /* metatable.__newindex = array.set */

  return 1;
}
//-------- Array End ------------------------------------------------------------

//--- lua中以字符串长度参数
static int crc8_hex(lua_State *L)
{
	u8 ucRet;
	size_t Len;
	short n = lua_gettop(L);	//参数个数
	char *pcStr;
	char pcTmp[3];

	pcStr = lua_tolstring(L, 1, &Len);	//获取第一个字符串参数
	lua_pop(L, 1);
	//pcStr = lua_tostring(L, 1);
	//DEBUGP("C:crc8-->argument %d, Len = %d, Data = %s, ", n, Len, pcStr);

	ucRet = CheckCRC8(pcStr, Len/2, 'H');

	sprintf(pcTmp, "%02X", ucRet);
	lua_pushstring(L, (const char *)pcTmp);		//返回值压栈
	//STACK_LIST(L);

	return 1;	//返回参数个数
}

//--- lua中以数组传递参数
static int crc8(lua_State *L)
{
	u8 ucret, ucdata[200];
	size_t len, i;
	char pctmp[3];

	NumArray *a = checkarray(L);
	len = lua_tonumber(L, 2);
	lua_pop(L, 2);

	for(i=0; ivalues[i];
		DEBUGP("%02X ", ucdata[i]);
	}
	ucret = CheckCRC8(ucdata, len, '0');

	sprintf(pctmp, "%02X", ucret);
	lua_pushstring(L, (const char *)pctmp);		//返回值压栈
	STACK_LIST(L);

	return 1;	//返回参数个数
}

---

lua代码:

-- 数组测试
alen = 100
a = array.new(alen)

alen = 6 --有效数组长度,
for i=1,alen do
a[i] = 0xf0 + i
end

str = "array = "
for i=1,alen do
str = str .. string.format("%02X", a[i])
end
print(str)

ret = owlib.crc8(a, alen) --传递有效长度
print("crc8 = 0x" .. ret)