Remove superfluous data copying in MSG_ReadDeltaPlayerstate

[Caball009]

The intention of this issue is only to remove a few instances of unnecessary data copying which should not change how the game functions.

The purpose of function MSG_ReadDeltaPlayerstate is to take an old playerState_s struct, copy it and apply a delta update (from serialized data) to it and store the result in a new playerState_s struct.

The first thing the function does is making a copy here; it makes a complete copy of old to new:

KisakCOD/src/qcommon/msg_mp.cpp

Line 1595 in ad50220

memcpy((unsigned __int8 *)to, (unsigned __int8 *)from, sizeof(playerState_s));

That means that the following partial copies are unnecessary (from top to bottom):

1. KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1624 to 1632 in ad50220

   	j = LastChangedField;
   	fielda = (NetField *)&playerStateFields[LastChangedField];
   	while (j < numPlayerStateFields)
   	{
   	v19 = (int *)((char *)&from->commandTime + fielda->offset);
   	*(int *)((char *)&to->commandTime + fielda->offset) = *v19;
   	++j;
   	++fielda;
   	}

   
   --

2. KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1649 to 1659 in ad50220

   	to->origin[0] = from->origin[0];
   	to->origin[1] = from->origin[1];
   	to->origin[2] = from->origin[2];
   	to->velocity[0] = from->velocity[0];
   	to->velocity[1] = from->velocity[1];
   	to->velocity[2] = from->velocity[2];
   	to->bobCycle = from->bobCycle;
   	to->movementDir = from->movementDir;
   	to->viewangles[0] = from->viewangles[0];
   	to->viewangles[1] = from->viewangles[1];
   	to->viewangles[2] = from->viewangles[2];

   
   --

3. KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1721 to 1727 in ad50220

   	MSG_ReadDeltaFields(
   	msg,
   	time,
   	(char *)&from->objective[j],
   	(char *)&to->objective[j],
   	numObjectiveFields,
   	objectiveFields);

   
   

   KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1763 to 1764 in ad50220

   	for (ia = 0; ia < numFields; ++ia)
   	*(unsigned int *)&to[stateFields[ia].offset] = *(unsigned int *)&from[stateFields[ia].offset];

   
   --

4. KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1732 to 1733 in ad50220

   	MSG_ReadDeltaHudElems(msg, time, from->hud.archival, to->hud.archival, 31);
   	MSG_ReadDeltaHudElems(msg, time, from->hud.current, to->hud.current, 31);

   
   

   KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1788 to 1792 in ad50220

   	while (j < numHudElemFields)
   	{
   	*(&to[i].type + hudElemFields[j].offset) = *(&from[i].type + hudElemFields[j].offset);
   	++j;
   	}

   
   --
   The second one is debatable and may depend on how the corresponding server side code works. It's possible that those fields were updated here below, but then it doesn't make sense that the server would expect the client to also use its own values for these fields.
   

   KisakCOD/src/qcommon/msg_mp.cpp

   Lines 1614 to 1617 in ad50220

   	if (predictedFieldsIgnoreXor && lc && field->changeHints == 3)
   	MSG_ReadDeltaField(msg, time, (char *)from, (char *)to, field, print, 1);
   	else
   	MSG_ReadDeltaField(msg, time, (char *)from, (char *)to, field, print, 0);

[LWSS]

Hey, I took a pass at this (above linked commit), let me know what you think.

It kinda looks to me as though the memcpy was added later on as a "fk it". It's probably better to get rid of the extra logic anyway.

I want to leave all the functions with MSG_ since they increment the msg bit count.

[LWSS]

actually this is in idtech3: https://github.com/grayj/Jedi-Academy/blob/d71d53e8ecc1edd300c7a9dd22b8fbc39c095423/code/qcommon/msg.cpp#L1136

interesting to see

[Caball009]

I left a couple of comments.

The current memcpy is quite large, about 12K bytes. It's possible to reduce this by 75% or more, but it'd require tracking in a separate variable how many of the hud elements are used. They take up a lot of space but are barely used most of the time. Might be something to look into in the future if you care about that.

EDIT: About the size of playerState_s, what also doesn't help is that the setup for (de)serialization assumes that the variables (those that are in the netfields) are at least 4 bytes. Even though some variables don't need to hold more data than a single byte, they can't be (without padding) because the (de)serialization would crash and burn.

[Caball009]

If it helps, you might want to have a look at the code here: https://github.com/Iswenzz/CoD4-DM1/blob/bb43514ee4675f2c090f6f8686b314d71b780989/src/Demo/Demo.cpp#L1004

[LWSS]

yeah that looks cool, we can clean this up a bit more later, I haven't started cleaning up the codebase file-by-file yet but will eventually