From 1aee560d866744cac71c39e81d02a4483e8d107f Mon Sep 17 00:00:00 2001
From: Barry Harris <44396066+barry65536@users.noreply.github.com>
Date: Mon, 21 Jan 2013 15:31:18 +0000
Subject: [PATCH] Optimise TC0100SCN char layer

---
 src/burn/drv/taito/tc0100scn.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/burn/drv/taito/tc0100scn.cpp b/src/burn/drv/taito/tc0100scn.cpp
index 90eac0176..a910363de 100644
--- a/src/burn/drv/taito/tc0100scn.cpp
+++ b/src/burn/drv/taito/tc0100scn.cpp
@@ -380,8 +380,12 @@ void TC0100SCNRenderCharLayer(INT32 Chip)
 		Rows = 32;
 	}
 	
-	GfxDecode(256, 2, 8, 8, TC0100SCNPlaneOffsets, TC0100SCNXOffsets, TC0100SCNYOffsets, 0x80, (UINT8*)CharRam, TC0100SCNChars[Chip]);
+	if (TC0100SCNCharRamUpdate[Chip]) {
+		GfxDecode(256, 2, 8, 8, TC0100SCNPlaneOffsets, TC0100SCNXOffsets, TC0100SCNYOffsets, 0x80, (UINT8*)CharRam, TC0100SCNChars[Chip]);
+		TC0100SCNCharRamUpdate[Chip] = 0;
+	}
 	
+	// we could use TC0100SCNCharLayerUpdate to render to a temp buffer, but since there is no row/col scroll here, it would probably be slower
 	for (my = 0; my < Rows; my++) {
 		for (mx = 0; mx < Columns; mx++) {
 			Attr = BURN_ENDIAN_SWAP_INT16(VideoRam[TileIndex]);
@@ -489,6 +493,8 @@ void TC0100SCNReset()
 		TC0100SCNDblWidth[i] = 0;
 		TC0100SCNBgLayerUpdate[i] = 1;
 		TC0100SCNFgLayerUpdate[i] = 1;
+		TC0100SCNCharLayerUpdate[i] = 1;
+		TC0100SCNCharRamUpdate[i] = 1;
 	}
 }
 
@@ -519,6 +525,8 @@ void TC0100SCNInit(INT32 Chip, INT32 nNumTiles, INT32 xOffset, INT32 yOffset, IN
 	TC0100SCNPaletteOffset[Chip] = 0;
 	TC0100SCNFgLayerUpdate[Chip] = 1;
 	TC0100SCNBgLayerUpdate[Chip] = 1;
+	TC0100SCNCharLayerUpdate[Chip] = 1;
+	TC0100SCNCharRamUpdate[Chip] = 1;
 	
 	if (!TC0100SCNClipWidth[Chip] || !TC0100SCNClipHeight[Chip]) bprintf(PRINT_IMPORTANT, _T("TC0100SCNInit called before GenericTilesInit\n"));
 	
@@ -584,6 +592,8 @@ void TC0100SCNExit()
 		TC0100SCNPaletteOffset[i] = 0;
 		TC0100SCNBgLayerUpdate[i] = 0;
 		TC0100SCNFgLayerUpdate[i] = 0;
+		TC0100SCNCharLayerUpdate[i] = 0;
+		TC0100SCNCharRamUpdate[i] = 0;
 	}
 	
 	TC0100SCNNum = 0;