From dcd2cabc9492a9d4929025e520157c1fa596a26f Mon Sep 17 00:00:00 2001
From: havoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Mon, 28 Jul 2003 23:47:05 +0000
Subject: [PATCH] added code for protocol 4, not hooked up or tested

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@3346 d7cf8633-e32d-0410-b094-e92efae38249
---
 protocol.c | 715 +++++++++++++++++++++++++++++++++++------------------
 protocol.h |  50 ++++
 2 files changed, 521 insertions(+), 244 deletions(-)

diff --git a/protocol.c b/protocol.c
index c24fea97..bd8b4f90 100644
--- a/protocol.c
+++ b/protocol.c
@@ -9,6 +9,261 @@ void ClearStateToDefault(entity_state_t *s)
 	s->glowcolor = 254;
 }
 
+void EntityState_Write(entity_state_t *ent, sizebuf_t *msg, entity_state_t *delta)
+{
+	int bits;
+	vec3_t org, deltaorg;
+	if (ent->active)
+	{
+		bits = 0;
+		VectorCopy(ent->origin, org);
+		VectorCopy(delta->origin, deltaorg);
+		if (ent->flags & RENDER_LOWPRECISION)
+		{
+			if (org[0] > 0)
+				org[0] = (int) (org[0] + 0.5f);
+			else
+				org[0] = (int) (org[0] - 0.5f);
+			if (org[1] > 0)
+				org[1] = (int) (org[1] + 0.5f);
+			else
+				org[1] = (int) (org[1] - 0.5f);
+			if (org[2] > 0)
+				org[2] = (int) (org[2] + 0.5f);
+			else
+				org[2] = (int) (org[2] - 0.5f);
+		}
+		if (delta->flags & RENDER_LOWPRECISION)
+		{
+			if (deltaorg[0] > 0)
+				deltaorg[0] = (int) (deltaorg[0] + 0.5f);
+			else
+				deltaorg[0] = (int) (deltaorg[0] - 0.5f);
+			if (deltaorg[1] > 0)
+				deltaorg[1] = (int) (deltaorg[1] + 0.5f);
+			else
+				deltaorg[1] = (int) (deltaorg[1] - 0.5f);
+			if (deltaorg[2] > 0)
+				deltaorg[2] = (int) (deltaorg[2] + 0.5f);
+			else
+				deltaorg[2] = (int) (deltaorg[2] - 0.5f);
+		}
+		if (fabs(org[0] - deltaorg[0]) > 0.01f)
+			bits |= E_ORIGIN1;
+		if (fabs(org[1] - deltaorg[1]) > 0.01f)
+			bits |= E_ORIGIN2;
+		if (fabs(org[2] - deltaorg[2]) > 0.01f)
+			bits |= E_ORIGIN3;
+		if ((qbyte) (ent->angles[0] * (256.0f / 360.0f)) != (qbyte) (delta->angles[0] * (256.0f / 360.0f)))
+			bits |= E_ANGLE1;
+		if ((qbyte) (ent->angles[1] * (256.0f / 360.0f)) != (qbyte) (delta->angles[1] * (256.0f / 360.0f)))
+			bits |= E_ANGLE2;
+		if ((qbyte) (ent->angles[2] * (256.0f / 360.0f)) != (qbyte) (delta->angles[2] * (256.0f / 360.0f)))
+			bits |= E_ANGLE3;
+		if ((ent->modelindex ^ delta->modelindex) & 0x00FF)
+			bits |= E_MODEL1;
+		if ((ent->modelindex ^ delta->modelindex) & 0xFF00)
+			bits |= E_MODEL2;
+		if ((ent->frame ^ delta->frame) & 0x00FF)
+			bits |= E_FRAME1;
+		if ((ent->frame ^ delta->frame) & 0xFF00)
+			bits |= E_FRAME2;
+		if ((ent->effects ^ delta->effects) & 0x00FF)
+			bits |= E_EFFECTS1;
+		if ((ent->effects ^ delta->effects) & 0xFF00)
+			bits |= E_EFFECTS2;
+		if (ent->colormap != delta->colormap)
+			bits |= E_COLORMAP;
+		if (ent->skin != delta->skin)
+			bits |= E_SKIN;
+		if (ent->alpha != delta->alpha)
+			bits |= E_ALPHA;
+		if (ent->scale != delta->scale)
+			bits |= E_SCALE;
+		if (ent->glowsize != delta->glowsize)
+			bits |= E_GLOWSIZE;
+		if (ent->glowcolor != delta->glowcolor)
+			bits |= E_GLOWCOLOR;
+		if (ent->flags != delta->flags)
+			bits |= E_FLAGS;
+		if (ent->tagindex != delta->tagindex || ent->tagentity != delta->tagentity)
+			bits |= E_TAGATTACHMENT;
+
+		if (bits) // don't send anything if it hasn't changed
+		{
+			if (bits & 0xFF000000)
+				bits |= E_EXTEND3;
+			if (bits & 0x00FF0000)
+				bits |= E_EXTEND2;
+			if (bits & 0x0000FF00)
+				bits |= E_EXTEND1;
+
+			MSG_WriteShort(msg, ent->number);
+			MSG_WriteByte(msg, bits & 0xFF);
+			if (bits & E_EXTEND1)
+			{
+				MSG_WriteByte(msg, (bits >> 8) & 0xFF);
+				if (bits & E_EXTEND2)
+				{
+					MSG_WriteByte(msg, (bits >> 16) & 0xFF);
+					if (bits & E_EXTEND3)
+						MSG_WriteByte(msg, (bits >> 24) & 0xFF);
+				}
+			}
+			// LordHavoc: have to write flags first, as they can modify protocol
+			if (bits & E_FLAGS)
+				MSG_WriteByte(msg, ent->flags);
+			if (ent->flags & RENDER_LOWPRECISION)
+			{
+				if (bits & E_ORIGIN1)
+					MSG_WriteShort(msg, org[0]);
+				if (bits & E_ORIGIN2)
+					MSG_WriteShort(msg, org[1]);
+				if (bits & E_ORIGIN3)
+					MSG_WriteShort(msg, org[2]);
+			}
+			else
+			{
+				if (bits & E_ORIGIN1)
+					MSG_WriteFloat(msg, org[0]);
+				if (bits & E_ORIGIN2)
+					MSG_WriteFloat(msg, org[1]);
+				if (bits & E_ORIGIN3)
+					MSG_WriteFloat(msg, org[2]);
+			}
+			if (bits & E_ANGLE1)
+				MSG_WriteAngle(msg, ent->angles[0]);
+			if (bits & E_ANGLE2)
+				MSG_WriteAngle(msg, ent->angles[1]);
+			if (bits & E_ANGLE3)
+				MSG_WriteAngle(msg, ent->angles[2]);
+			if (bits & E_MODEL1)
+				MSG_WriteByte(msg, ent->modelindex & 0xFF);
+			if (bits & E_MODEL2)
+				MSG_WriteByte(msg, (ent->modelindex >> 8) & 0xFF);
+			if (bits & E_FRAME1)
+				MSG_WriteByte(msg, ent->frame & 0xFF);
+			if (bits & E_FRAME2)
+				MSG_WriteByte(msg, (ent->frame >> 8) & 0xFF);
+			if (bits & E_EFFECTS1)
+				MSG_WriteByte(msg, ent->effects & 0xFF);
+			if (bits & E_EFFECTS2)
+				MSG_WriteByte(msg, (ent->effects >> 8) & 0xFF);
+			if (bits & E_COLORMAP)
+				MSG_WriteByte(msg, ent->colormap);
+			if (bits & E_SKIN)
+				MSG_WriteByte(msg, ent->skin);
+			if (bits & E_ALPHA)
+				MSG_WriteByte(msg, ent->alpha);
+			if (bits & E_SCALE)
+				MSG_WriteByte(msg, ent->scale);
+			if (bits & E_GLOWSIZE)
+				MSG_WriteByte(msg, ent->glowsize);
+			if (bits & E_GLOWCOLOR)
+				MSG_WriteByte(msg, ent->glowcolor);
+			if (bits & E_TAGATTACHMENT)
+			{
+				MSG_WriteShort(msg, ent->tagentity);
+				MSG_WriteByte(msg, ent->tagindex);
+			}
+		}
+	}
+	else if (!delta->active)
+		MSG_WriteShort(msg, ent->number | 0x8000);
+}
+
+void EntityState_Read(entity_state_t *e, entity_state_t *delta, int number)
+{
+	int bits;
+	memcpy(e, delta, sizeof(*e));
+	e->active = true;
+	e->time = cl.mtime[0];
+	e->number = number;
+
+	bits = MSG_ReadByte();
+	if (bits & E_EXTEND1)
+	{
+		bits |= MSG_ReadByte() << 8;
+		if (bits & E_EXTEND2)
+		{
+			bits |= MSG_ReadByte() << 16;
+			if (bits & E_EXTEND3)
+				bits |= MSG_ReadByte() << 24;
+		}
+	}
+
+	if (dpprotocol == DPPROTOCOL_VERSION2)
+	{
+		if (bits & E_ORIGIN1)
+			e->origin[0] = (signed short) MSG_ReadShort();
+		if (bits & E_ORIGIN2)
+			e->origin[1] = (signed short) MSG_ReadShort();
+		if (bits & E_ORIGIN3)
+			e->origin[2] = (signed short) MSG_ReadShort();
+	}
+	else
+	{
+		if (bits & E_FLAGS)
+			e->flags = MSG_ReadByte();
+		if (e->flags & RENDER_LOWPRECISION || dpprotocol == DPPROTOCOL_VERSION2)
+		{
+			if (bits & E_ORIGIN1)
+				e->origin[0] = (signed short) MSG_ReadShort();
+			if (bits & E_ORIGIN2)
+				e->origin[1] = (signed short) MSG_ReadShort();
+			if (bits & E_ORIGIN3)
+				e->origin[2] = (signed short) MSG_ReadShort();
+		}
+		else
+		{
+			if (bits & E_ORIGIN1)
+				e->origin[0] = MSG_ReadFloat();
+			if (bits & E_ORIGIN2)
+				e->origin[1] = MSG_ReadFloat();
+			if (bits & E_ORIGIN3)
+				e->origin[2] = MSG_ReadFloat();
+		}
+	}
+	if (bits & E_ANGLE1)
+		e->angles[0] = MSG_ReadAngle();
+	if (bits & E_ANGLE2)
+		e->angles[1] = MSG_ReadAngle();
+	if (bits & E_ANGLE3)
+		e->angles[2] = MSG_ReadAngle();
+	if (bits & E_MODEL1)
+		e->modelindex = (e->modelindex & 0xFF00) | (unsigned int) MSG_ReadByte();
+	if (bits & E_MODEL2)
+		e->modelindex = (e->modelindex & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
+	if (bits & E_FRAME1)
+		e->frame = (e->frame & 0xFF00) | (unsigned int) MSG_ReadByte();
+	if (bits & E_FRAME2)
+		e->frame = (e->frame & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
+	if (bits & E_EFFECTS1)
+		e->effects = (e->effects & 0xFF00) | (unsigned int) MSG_ReadByte();
+	if (bits & E_EFFECTS2)
+		e->effects = (e->effects & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
+	if (bits & E_COLORMAP)
+		e->colormap = MSG_ReadByte();
+	if (bits & E_SKIN)
+		e->skin = MSG_ReadByte();
+	if (bits & E_ALPHA)
+		e->alpha = MSG_ReadByte();
+	if (bits & E_SCALE)
+		e->scale = MSG_ReadByte();
+	if (bits & E_GLOWSIZE)
+		e->glowsize = MSG_ReadByte();
+	if (bits & E_GLOWCOLOR)
+		e->glowcolor = MSG_ReadByte();
+	if (dpprotocol == DPPROTOCOL_VERSION2)
+		if (bits & E_FLAGS)
+			e->flags = MSG_ReadByte();
+	if (bits & E_TAGATTACHMENT)
+	{
+		e->tagentity = MSG_ReadShort();
+		e->tagindex = MSG_ReadByte();
+	}
+}
+
 // (server) clears the database to contain no frames (thus delta compression compresses against nothing)
 void EntityFrame_ClearDatabase(entity_database_t *d)
 {
@@ -133,8 +388,7 @@ void EntityFrame_AddFrame(entity_database_t *d, entity_frame_t *f)
 static entity_frame_t deltaframe; // FIXME?
 void EntityFrame_Write(entity_database_t *d, entity_frame_t *f, sizebuf_t *msg)
 {
-	int i, onum, bits, number;
-	float org[3], deltaorg[3];
+	int i, onum, number;
 	entity_frame_t *o = &deltaframe;
 	entity_state_t *ent, *delta, baseline;
 
@@ -171,158 +425,7 @@ void EntityFrame_Write(entity_database_t *d, entity_frame_t *f, sizebuf_t *msg)
 			// delta from baseline
 			delta = &baseline;
 		}
-		bits = 0;
-		VectorCopy(ent->origin, org);
-		VectorCopy(delta->origin, deltaorg);
-		if (ent->flags & RENDER_LOWPRECISION)
-		{
-			if (org[0] > 0)
-				org[0] = (int) (org[0] + 0.5f);
-			else
-				org[0] = (int) (org[0] - 0.5f);
-			if (org[1] > 0)
-				org[1] = (int) (org[1] + 0.5f);
-			else
-				org[1] = (int) (org[1] - 0.5f);
-			if (org[2] > 0)
-				org[2] = (int) (org[2] + 0.5f);
-			else
-				org[2] = (int) (org[2] - 0.5f);
-		}
-		if (delta->flags & RENDER_LOWPRECISION)
-		{
-			if (deltaorg[0] > 0)
-				deltaorg[0] = (int) (deltaorg[0] + 0.5f);
-			else
-				deltaorg[0] = (int) (deltaorg[0] - 0.5f);
-			if (deltaorg[1] > 0)
-				deltaorg[1] = (int) (deltaorg[1] + 0.5f);
-			else
-				deltaorg[1] = (int) (deltaorg[1] - 0.5f);
-			if (deltaorg[2] > 0)
-				deltaorg[2] = (int) (deltaorg[2] + 0.5f);
-			else
-				deltaorg[2] = (int) (deltaorg[2] - 0.5f);
-		}
-		if (fabs(org[0] - deltaorg[0]) > 0.01f)
-			bits |= E_ORIGIN1;
-		if (fabs(org[1] - deltaorg[1]) > 0.01f)
-			bits |= E_ORIGIN2;
-		if (fabs(org[2] - deltaorg[2]) > 0.01f)
-			bits |= E_ORIGIN3;
-		if ((qbyte) (ent->angles[0] * (256.0f / 360.0f)) != (qbyte) (delta->angles[0] * (256.0f / 360.0f)))
-			bits |= E_ANGLE1;
-		if ((qbyte) (ent->angles[1] * (256.0f / 360.0f)) != (qbyte) (delta->angles[1] * (256.0f / 360.0f)))
-			bits |= E_ANGLE2;
-		if ((qbyte) (ent->angles[2] * (256.0f / 360.0f)) != (qbyte) (delta->angles[2] * (256.0f / 360.0f)))
-			bits |= E_ANGLE3;
-		if ((ent->modelindex ^ delta->modelindex) & 0x00FF)
-			bits |= E_MODEL1;
-		if ((ent->modelindex ^ delta->modelindex) & 0xFF00)
-			bits |= E_MODEL2;
-		if ((ent->frame ^ delta->frame) & 0x00FF)
-			bits |= E_FRAME1;
-		if ((ent->frame ^ delta->frame) & 0xFF00)
-			bits |= E_FRAME2;
-		if ((ent->effects ^ delta->effects) & 0x00FF)
-			bits |= E_EFFECTS1;
-		if ((ent->effects ^ delta->effects) & 0xFF00)
-			bits |= E_EFFECTS2;
-		if (ent->colormap != delta->colormap)
-			bits |= E_COLORMAP;
-		if (ent->skin != delta->skin)
-			bits |= E_SKIN;
-		if (ent->alpha != delta->alpha)
-			bits |= E_ALPHA;
-		if (ent->scale != delta->scale)
-			bits |= E_SCALE;
-		if (ent->glowsize != delta->glowsize)
-			bits |= E_GLOWSIZE;
-		if (ent->glowcolor != delta->glowcolor)
-			bits |= E_GLOWCOLOR;
-		if (ent->flags != delta->flags)
-			bits |= E_FLAGS;
-		if (ent->tagindex != delta->tagindex || ent->tagentity != delta->tagentity)
-			bits |= E_TAGATTACHMENT;
-
-		if (bits) // don't send anything if it hasn't changed
-		{
-			if (bits & 0xFF000000)
-				bits |= E_EXTEND3;
-			if (bits & 0x00FF0000)
-				bits |= E_EXTEND2;
-			if (bits & 0x0000FF00)
-				bits |= E_EXTEND1;
-
-			MSG_WriteShort(msg, number);
-			MSG_WriteByte(msg, bits & 0xFF);
-			if (bits & E_EXTEND1)
-			{
-				MSG_WriteByte(msg, (bits >> 8) & 0xFF);
-				if (bits & E_EXTEND2)
-				{
-					MSG_WriteByte(msg, (bits >> 16) & 0xFF);
-					if (bits & E_EXTEND3)
-						MSG_WriteByte(msg, (bits >> 24) & 0xFF);
-				}
-			}
-			// LordHavoc: have to write flags first, as they can modify protocol
-			if (bits & E_FLAGS)
-				MSG_WriteByte(msg, ent->flags);
-			if (ent->flags & RENDER_LOWPRECISION)
-			{
-				if (bits & E_ORIGIN1)
-					MSG_WriteShort(msg, org[0]);
-				if (bits & E_ORIGIN2)
-					MSG_WriteShort(msg, org[1]);
-				if (bits & E_ORIGIN3)
-					MSG_WriteShort(msg, org[2]);
-			}
-			else
-			{
-				if (bits & E_ORIGIN1)
-					MSG_WriteFloat(msg, org[0]);
-				if (bits & E_ORIGIN2)
-					MSG_WriteFloat(msg, org[1]);
-				if (bits & E_ORIGIN3)
-					MSG_WriteFloat(msg, org[2]);
-			}
-			if (bits & E_ANGLE1)
-				MSG_WriteAngle(msg, ent->angles[0]);
-			if (bits & E_ANGLE2)
-				MSG_WriteAngle(msg, ent->angles[1]);
-			if (bits & E_ANGLE3)
-				MSG_WriteAngle(msg, ent->angles[2]);
-			if (bits & E_MODEL1)
-				MSG_WriteByte(msg, ent->modelindex & 0xFF);
-			if (bits & E_MODEL2)
-				MSG_WriteByte(msg, (ent->modelindex >> 8) & 0xFF);
-			if (bits & E_FRAME1)
-				MSG_WriteByte(msg, ent->frame & 0xFF);
-			if (bits & E_FRAME2)
-				MSG_WriteByte(msg, (ent->frame >> 8) & 0xFF);
-			if (bits & E_EFFECTS1)
-				MSG_WriteByte(msg, ent->effects & 0xFF);
-			if (bits & E_EFFECTS2)
-				MSG_WriteByte(msg, (ent->effects >> 8) & 0xFF);
-			if (bits & E_COLORMAP)
-				MSG_WriteByte(msg, ent->colormap);
-			if (bits & E_SKIN)
-				MSG_WriteByte(msg, ent->skin);
-			if (bits & E_ALPHA)
-				MSG_WriteByte(msg, ent->alpha);
-			if (bits & E_SCALE)
-				MSG_WriteByte(msg, ent->scale);
-			if (bits & E_GLOWSIZE)
-				MSG_WriteByte(msg, ent->glowsize);
-			if (bits & E_GLOWCOLOR)
-				MSG_WriteByte(msg, ent->glowcolor);
-			if (bits & E_TAGATTACHMENT)
-			{
-				MSG_WriteShort(msg, ent->tagentity);
-				MSG_WriteByte(msg, ent->tagindex);
-			}
-		}
+		EntityState_Write(ent, msg, delta);
 	}
 	for (;onum < o->numentities;onum++)
 	{
@@ -336,9 +439,9 @@ void EntityFrame_Write(entity_database_t *d, entity_frame_t *f, sizebuf_t *msg)
 static entity_frame_t framedata; // FIXME?
 void EntityFrame_Read(entity_database_t *d)
 {
-	int number, removed, bits;
+	int number, removed;
 	entity_frame_t *f = &framedata, *delta = &deltaframe;
-	entity_state_t *e, baseline, *old, *oldend;
+	entity_state_t *e, baseline, *old, *oldend, *edelta;
 
 	ClearStateToDefault(&baseline);
 
@@ -393,100 +496,15 @@ void EntityFrame_Read(entity_database_t *d)
 			if (old < oldend && old->number == number)
 			{
 				// delta from old entity
-				memcpy(e, old++, sizeof(*e));
+				edelta = old++;
 			}
 			else
 			{
 				// delta from baseline
-				memcpy(e, &baseline, sizeof(*e));
+				edelta = &baseline;
 			}
 
-			e->active = true;
-			e->time = cl.mtime[0];
-			e->number = number;
-
-			bits = MSG_ReadByte();
-			if (bits & E_EXTEND1)
-			{
-				bits |= MSG_ReadByte() << 8;
-				if (bits & E_EXTEND2)
-				{
-					bits |= MSG_ReadByte() << 16;
-					if (bits & E_EXTEND3)
-						bits |= MSG_ReadByte() << 24;
-				}
-			}
-
-			if (dpprotocol == DPPROTOCOL_VERSION2)
-			{
-				if (bits & E_ORIGIN1)
-					e->origin[0] = (signed short) MSG_ReadShort();
-				if (bits & E_ORIGIN2)
-					e->origin[1] = (signed short) MSG_ReadShort();
-				if (bits & E_ORIGIN3)
-					e->origin[2] = (signed short) MSG_ReadShort();
-			}
-			else
-			{
-				if (bits & E_FLAGS)
-					e->flags = MSG_ReadByte();
-				if (e->flags & RENDER_LOWPRECISION || dpprotocol == DPPROTOCOL_VERSION2)
-				{
-					if (bits & E_ORIGIN1)
-						e->origin[0] = (signed short) MSG_ReadShort();
-					if (bits & E_ORIGIN2)
-						e->origin[1] = (signed short) MSG_ReadShort();
-					if (bits & E_ORIGIN3)
-						e->origin[2] = (signed short) MSG_ReadShort();
-				}
-				else
-				{
-					if (bits & E_ORIGIN1)
-						e->origin[0] = MSG_ReadFloat();
-					if (bits & E_ORIGIN2)
-						e->origin[1] = MSG_ReadFloat();
-					if (bits & E_ORIGIN3)
-						e->origin[2] = MSG_ReadFloat();
-				}
-			}
-			if (bits & E_ANGLE1)
-				e->angles[0] = MSG_ReadAngle();
-			if (bits & E_ANGLE2)
-				e->angles[1] = MSG_ReadAngle();
-			if (bits & E_ANGLE3)
-				e->angles[2] = MSG_ReadAngle();
-			if (bits & E_MODEL1)
-				e->modelindex = (e->modelindex & 0xFF00) | (unsigned int) MSG_ReadByte();
-			if (bits & E_MODEL2)
-				e->modelindex = (e->modelindex & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
-			if (bits & E_FRAME1)
-				e->frame = (e->frame & 0xFF00) | (unsigned int) MSG_ReadByte();
-			if (bits & E_FRAME2)
-				e->frame = (e->frame & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
-			if (bits & E_EFFECTS1)
-				e->effects = (e->effects & 0xFF00) | (unsigned int) MSG_ReadByte();
-			if (bits & E_EFFECTS2)
-				e->effects = (e->effects & 0x00FF) | ((unsigned int) MSG_ReadByte() << 8);
-			if (bits & E_COLORMAP)
-				e->colormap = MSG_ReadByte();
-			if (bits & E_SKIN)
-				e->skin = MSG_ReadByte();
-			if (bits & E_ALPHA)
-				e->alpha = MSG_ReadByte();
-			if (bits & E_SCALE)
-				e->scale = MSG_ReadByte();
-			if (bits & E_GLOWSIZE)
-				e->glowsize = MSG_ReadByte();
-			if (bits & E_GLOWCOLOR)
-				e->glowcolor = MSG_ReadByte();
-			if (dpprotocol == DPPROTOCOL_VERSION2)
-				if (bits & E_FLAGS)
-					e->flags = MSG_ReadByte();
-			if (bits & E_TAGATTACHMENT)
-			{
-				e->tagentity = MSG_ReadShort();
-				e->tagindex = MSG_ReadByte();
-			}
+			EntityState_Read(e, edelta, number);
 		}
 	}
 	while (old < oldend)
@@ -511,3 +529,212 @@ int EntityFrame_MostRecentlyRecievedFrameNum(entity_database_t *d)
 		return -1;
 }
 
+
+
+
+
+
+static int EntityFrame4_SV_ChooseCommitToReplace(entity_database4_t *d)
+{
+	int i, best, bestframenum;
+	best = 0;
+	bestframenum = d->commit[0].framenum;
+	for (i = 0;i < MAX_ENTITY_HISTORY;i++)
+	{
+		if (!d->commit[i].numentities)
+			return i;
+		if (bestframenum > d->commit[i].framenum)
+		{
+			bestframenum = d->commit[i].framenum;
+			best = i;
+		}
+	}
+	return best;
+}
+
+static entity_state_t *EntityFrame4_GetReferenceEntity(entity_database4_t *d, int number)
+{
+	if (d->maxreferenceentities <= number)
+	{
+		int oldmax = d->maxreferenceentities;
+		entity_state_t *oldentity = d->referenceentity;
+		d->maxreferenceentities = (number + 15) & ~7;
+		d->referenceentity = Mem_Alloc(d->mempool, d->maxreferenceentities * sizeof(*d->referenceentity));
+		if (oldentity)
+		{
+			memcpy(d->referenceentity, oldentity, oldmax * sizeof(*d->referenceentity));
+			Mem_Free(oldentity);
+		}
+		// clear the newly created entities
+		for (;oldmax < d->maxreferenceentities;oldmax++)
+			ClearStateToDefault(d->referenceentity + oldmax);
+	}
+	return d->referenceentity + number;
+}
+
+static void EntityFrame4_AddCommitEntity(entity_database4_t *d, entity_state_t *s)
+{
+	// resize commit's entity list if full
+	if (d->currentcommit->maxentities <= d->currentcommit->numentities)
+	{
+		entity_state_t *oldentity = d->currentcommit->entity;
+		d->currentcommit->maxentities += 8;
+		d->currentcommit->entity = Mem_Alloc(d->mempool, d->currentcommit->maxentities * sizeof(*d->currentcommit->entity));
+		if (oldentity)
+		{
+			memcpy(d->currentcommit->entity, oldentity, d->currentcommit->numentities * sizeof(*d->currentcommit->entity));
+			Mem_Free(oldentity);
+		}
+	}
+	d->currentcommit->entity[d->currentcommit->numentities++] = *s;
+}
+
+entity_database4_t *EntityFrame4_AllocDatabase(mempool_t *pool)
+{
+	entity_database4_t *d;
+	d = Mem_Alloc(pool, sizeof(*d));
+	d->mempool = pool;
+	d->referenceframenum = -1;
+	return d;
+}
+
+void EntityFrame4_FreeDatabase(entity_database4_t *d)
+{
+	int i;
+	for (i = 0;i < MAX_ENTITY_HISTORY;i++)
+		if (d->commit[i].entity)
+			Mem_Free(d->commit[i].entity);
+	if (d->referenceentity)
+		Mem_Free(d->referenceentity);
+	Mem_Free(d);
+}
+
+void EntityFrame4_ResetDatabase(entity_database4_t *d)
+{
+	int i;
+	d->referenceframenum = -1;
+	for (i = 0;i < MAX_ENTITY_HISTORY;i++)
+		d->commit[i].numentities = 0;
+}
+
+void EntityFrame4_AckFrame(entity_database4_t *d, int framenum)
+{
+	int i, foundit = false;
+	// check if client is requesting no delta compression
+	if (framenum == -1)
+	{
+		EntityFrame4_ResetDatabase(d);
+		return;
+	}
+	for (i = 0;i < MAX_ENTITY_HISTORY;i++)
+	{
+		if (d->commit[i].numentities && d->commit[i].framenum <= framenum)
+		{
+			if (d->commit[i].framenum == framenum)
+			{
+				// apply commit to database
+				d->referenceframenum = d->commit[i].framenum;
+				while (d->commit[i].numentities--)
+					*EntityFrame4_GetReferenceEntity(d, d->commit[i].entity[d->commit[i].numentities].number) = d->commit[i].entity[d->commit[i].numentities];
+				foundit = true;
+			}
+			d->commit[i].numentities = 0;
+			d->commit[i].framenum = -1;
+		}
+	}
+	if (!foundit)
+		Con_DPrintf("EntityFrame4_AckFrame: frame %i not found in database, expect glitches!\n", framenum);
+}
+
+void EntityFrame4_SV_WriteFrame_Begin(entity_database4_t *d, sizebuf_t *msg, int framenum)
+{
+	d->currentcommit = d->commit + EntityFrame4_SV_ChooseCommitToReplace(d);
+	d->currentcommit->numentities = 0;
+	d->currentcommit->framenum = framenum;
+	MSG_WriteByte(msg, svc_entities);
+	MSG_WriteLong(msg, d->referenceframenum);
+	MSG_WriteLong(msg, d->currentcommit->framenum);
+}
+
+int EntityFrame4_SV_WriteFrame_Entity(entity_database4_t *d, sizebuf_t *msg, int maxbytes, entity_state_t *s)
+{
+	qbyte data[128];
+	sizebuf_t buf;
+	entity_state_t *e;
+	// prepare the buffer
+	memset(&buf, 0, sizeof(buf));
+	buf.data = data;
+	buf.maxsize = sizeof(data);
+	// make the message
+	e = EntityFrame4_GetReferenceEntity(d, s->number);
+	if (s->active)
+	{
+		// entity exists, send an update
+		EntityState_Write(s, &buf, e);
+	}
+	else if (e->active)
+	{
+		// entity used to exist but doesn't anymore, send remove
+		MSG_WriteShort(&buf, s->number | 0x8000);
+	}
+	// if the message is empty, skip out now
+	if (!buf.cursize)
+		return true;
+	// if the commit is full, we're done
+	if (msg->cursize + buf.cursize + 2 >= min(msg->maxsize, maxbytes))
+		return false;
+	// add the entity to the commit
+	EntityFrame4_AddCommitEntity(d, s);
+	// write the message to the packet
+	SZ_Write(msg, buf.data, buf.cursize);
+	// carry on
+	return true;
+}
+
+void EntityFrame4_SV_WriteFrame_End(entity_database4_t *d, sizebuf_t *msg)
+{
+	// remove world message (invalid, and thus a good terminator)
+	MSG_WriteShort(msg, 0x8000);
+	// just to be sure
+	d->currentcommit = NULL;
+}
+
+void EntityFrame4_CL_ReadFrame(entity_database4_t *d)
+{
+	int i, n, number, referenceframenum, framenum;
+	referenceframenum = MSG_ReadLong();
+	framenum = MSG_ReadLong();
+	EntityFrame4_AckFrame(d, referenceframenum);
+	for (i = 0;i < MAX_ENTITY_HISTORY;i++)
+		if (!d->commit[i].numentities)
+			break;
+	if (i < MAX_ENTITY_HISTORY)
+	{
+		d->currentcommit = d->commit + i;
+		d->currentcommit->framenum = framenum;
+		d->currentcommit->numentities = 0;
+	}
+	else
+	{
+		Con_Printf("EntityFrame4_CL_ReadFrame: error while decoding frame %i: database full, resetting, expect glitches!!\n", framenum);
+		d->currentcommit = NULL;
+		EntityFrame4_ResetDatabase(d);
+	}
+	while((n = MSG_ReadShort()) != 0x8000)
+	{
+		number = n & 0x7FFF;
+		cl_entities[number].state_previous = cl_entities[number].state_current;
+		if (number & 0x8000)
+		{
+			ClearStateToDefault(&cl_entities[number].state_current);
+			cl_entities[number].state_current.active = false;
+			cl_entities[number].state_current.number = number;
+		}
+		else
+			EntityState_Read(&cl_entities[number].state_current, EntityFrame4_GetReferenceEntity(d, number), number);
+		if (d->currentcommit)
+			EntityFrame4_AddCommitEntity(d, &cl_entities[number].state_current);
+	}
+	d->currentcommit = NULL;
+}
+
diff --git a/protocol.h b/protocol.h
index 0256ea3d..3950fa49 100644
--- a/protocol.h
+++ b/protocol.h
@@ -506,5 +506,55 @@ void EntityFrame_Read(entity_database_t *d);
 // (client) returns the frame number of the most recent frame recieved
 int EntityFrame_MostRecentlyRecievedFrameNum(entity_database_t *d);
 
+typedef struct entity_database4_commit_s
+{
+	// frame number this commit represents
+	int framenum;
+	// number of entities in entity[] array
+	int numentities;
+	// maximum number of entities in entity[] array (dynamic resizing)
+	int maxentities;
+	entity_state_t *entity;
+}
+entity_database4_commit_t;
+
+typedef struct entity_database4_s
+{
+	// what mempool to use for allocations
+	mempool_t *mempool;
+	// reference frame
+	int referenceframenum;
+	// reference entities array is resized according to demand
+	int maxreferenceentities;
+	// array of states for entities, these are indexable by their entity number (yes there are gaps)
+	entity_state_t *referenceentity;
+	// commits waiting to be applied to the reference database when confirmed
+	// (commit[i]->numentities == 0 means it is empty)
+	entity_database4_commit_t commit[MAX_ENTITY_HISTORY];
+	// used only while building a commit
+	entity_database4_commit_t *currentcommit;
+}
+entity_database4_t;
+
+// allocate a database
+entity_database4_t *EntityFrame4_AllocDatabase(mempool_t *pool);
+// free a database
+void EntityFrame4_FreeDatabase(entity_database4_t *d);
+// reset a database (resets compression but does not reallocate anything)
+void EntityFrame4_ResetDatabase(entity_database4_t *d);
+// updates database to account for a frame-received acknowledgment
+void EntityFrame4_AckFrame(entity_database4_t *d, int framenum);
+
+// begin writing a frame
+void EntityFrame4_SV_WriteFrame_Begin(entity_database4_t *d, sizebuf_t *msg, int framenum);
+// write an entity in the frame
+// returns false if full
+int EntityFrame4_SV_WriteFrame_Entity(entity_database4_t *d, sizebuf_t *msg, int maxbytes, entity_state_t *s);
+// end writing a frame
+void EntityFrame4_SV_WriteFrame_End(entity_database4_t *d, sizebuf_t *msg);
+
+// reads a frame from the network stream
+void EntityFrame4_CL_ReadFrame(entity_database4_t *d);
+
 #endif
 
-- 
2.39.2