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Update the luaval_to_int32 conversional function to get correct value

This commit is contained in:
samuele3hu 2015-01-16 09:50:22 +08:00
parent 8f8194fbc8
commit 4601331dee
1 changed files with 16 additions and 1 deletions
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17
cocos/scripting/lua-bindings/manual/LuaBasicConversions.cpp
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@ -121,7 +121,22 @@ bool luaval_to_int32(lua_State* L,int lo,int* outValue, const char* funcName)
if (ok)
{
*outValue = (int)(unsigned int)lua_tonumber(L, lo);
/**
When we want to convert the number value from the Lua to int, we would call lua_tonumber to implement.It would
experience two phase conversion: int -> double, double->int.But,for the 0x80000000 which the min value of int, the
int cast may return an undefined result,like 0x7fffffff.So we must use the (int)(unsigned int)lua_tonumber() to get
predictable results for 0x80000000.In this place,we didn't use lua_tointeger, because it may produce differen results
depending on the compiler,e.g:for iPhone4s,it also get wrong value for 0x80000000.
*/
unsigned int estimateValue = (unsigned int)lua_tonumber(L, lo);
if (estimateValue == std::numeric_limits<int>::min())
{
*outValue = (int)estimateValue;
}
else
{
*outValue = (int)lua_tonumber(L, lo);
}
}
return ok;