diff --git a/Makefile.mingw b/Makefile.mingw
index 8ea1c471b..9200f0949 100644
--- a/Makefile.mingw
+++ b/Makefile.mingw
@@ -7,7 +7,7 @@
 # Where did you install the FMOD API to? Change this line so that the build process can find it.
 FMODDIR = "c:/program files/fmodapi375win"
 
-ifeq ($(findstring msys,$(shell sh --version 2>nul)),msys)
+ifeq ($(findstring msys,$(shell sh --version 2>nul)),msys)
   WINCMD=0
 else
   WINCMD=1
diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 69cdf4b4e..af2594224 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,3 +1,17 @@
+February 26, 2008
+- Added an assembly version of rt_shaded4cols, since that's the main decal
+  drawing function. The most improvement came from being able to turn some
+  constant variables into immediate values with self-modifying code, but I
+  also managed to reorder it to make it a little faster. It's about 9% faster
+  than VC++'s code and 19% faster than GCC's code. That's not a huge
+  improvement (for VC++), but at least it's measurable.
+- Removed the solid fill "optimization" from rt_shaded4cols(), because in my
+  testing, it didn't help any and in fact, hurt just a little bit.
+- In the name of simplification, all the rt_tlate* drawers were changed to do
+  the translation in one step and the drawing in another. This lets me call
+  the untranslated drawer to do the real drawing instead of mostly duplicating
+  them. Performance wise, there is practically no difference from before.
+
 February 25, 2008 (Changes by Graf Zahl)
 - Fixed: The DECORATE expression evaluator's random function could produce
   incorrect results for ranges > 255. Changed so that FRandom's default
diff --git a/src/r_draw.cpp b/src/r_draw.cpp
index 7c61b1f8c..acb5413a9 100644
--- a/src/r_draw.cpp
+++ b/src/r_draw.cpp
@@ -80,6 +80,7 @@ int				detailyshift;		// [RH] Y shift for vertical detail level
 extern "C" void STACK_ARGS DoubleHoriz_MMX (int height, int width, BYTE *dest, int pitch);
 extern "C" void STACK_ARGS DoubleHorizVert_MMX (int height, int width, BYTE *dest, int pitch);
 extern "C" void STACK_ARGS DoubleVert_ASM (int height, int width, BYTE *dest, int pitch);
+extern "C" void R_SetupShadedCol();
 #endif
 
 // [RH] Pointers to the different column drawers.
@@ -94,7 +95,7 @@ void (*R_DrawSpan)(void);
 void (*R_DrawSpanMasked)(void);
 void (*R_DrawSpanTranslucent)(void);
 void (*R_DrawSpanMaskedTranslucent)(void);
-void (*rt_map4cols)(int,int,int);
+void (STACK_ARGS *rt_map4cols)(int,int,int);
 
 //
 // R_DrawColumn
@@ -2270,6 +2271,7 @@ ESPSResult R_SetPatchStyle (FRenderStyle style, fixed_t alpha, int translation,
 		{
 			dc_colormap += fixedlightlev;
 		}
+		R_SetupShadedCol();
 		return r_columnmethod ? DoDraw1 : DoDraw0;
 	}
 
diff --git a/src/r_draw.h b/src/r_draw.h
index 7193bfe30..23ec1b74b 100644
--- a/src/r_draw.h
+++ b/src/r_draw.h
@@ -106,47 +106,59 @@ void R_DrawMaskedColumnHoriz (const BYTE *column, const FTexture::Span *spans);
 void R_InitColumnDrawers ();
 
 // [RH] Moves data from the temporary buffer to the screen.
+extern "C"
+{
 void rt_copy1col_c (int hx, int sx, int yl, int yh);
-void rt_copy4cols_c (int sx, int yl, int yh);
-void rt_map1col_c (int hx, int sx, int yl, int yh);
-void rt_map4cols_c (int sx, int yl, int yh);
-void rt_add1col (int hx, int sx, int yl, int yh);
-void rt_add4cols (int sx, int yl, int yh);
-void rt_tlate1col (int hx, int sx, int yl, int yh);
-void rt_tlate4cols (int sx, int yl, int yh);
-void rt_tlateadd1col (int hx, int sx, int yl, int yh);
-void rt_tlateadd4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_copy4cols_c (int sx, int yl, int yh);
+
 void rt_shaded1col (int hx, int sx, int yl, int yh);
-void rt_shaded4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_shaded4cols_c (int sx, int yl, int yh);
+void STACK_ARGS rt_shaded4cols_asm (int sx, int yl, int yh);
+
+void rt_map1col_c (int hx, int sx, int yl, int yh);
+void rt_add1col (int hx, int sx, int yl, int yh);
 void rt_addclamp1col (int hx, int sx, int yl, int yh);
-void rt_addclamp4cols (int sx, int yl, int yh);
-void rt_tlateaddclamp1col (int hx, int sx, int yl, int yh);
-void rt_tlateaddclamp4cols (int sx, int yl, int yh);
 void rt_subclamp1col (int hx, int sx, int yl, int yh);
-void rt_subclamp4cols (int sx, int yl, int yh);
-void rt_tlatesubclamp1col (int hx, int sx, int yl, int yh);
-void rt_tlatesubclamp4cols (int sx, int yl, int yh);
 void rt_revsubclamp1col (int hx, int sx, int yl, int yh);
-void rt_revsubclamp4cols (int sx, int yl, int yh);
+
+void rt_tlate1col (int hx, int sx, int yl, int yh);
+void rt_tlateadd1col (int hx, int sx, int yl, int yh);
+void rt_tlateaddclamp1col (int hx, int sx, int yl, int yh);
+void rt_tlatesubclamp1col (int hx, int sx, int yl, int yh);
 void rt_tlaterevsubclamp1col (int hx, int sx, int yl, int yh);
-void rt_tlaterevsubclamp4cols (int sx, int yl, int yh);
 
-extern "C" void rt_copy1col_asm (int hx, int sx, int yl, int yh);
-extern "C" void rt_copy4cols_asm (int sx, int yl, int yh);
-extern "C" void rt_map1col_asm (int hx, int sx, int yl, int yh);
-extern "C" void rt_map4cols_asm1 (int sx, int yl, int yh);
-extern "C" void rt_map4cols_asm2 (int sx, int yl, int yh);
+void STACK_ARGS rt_map4cols_c (int sx, int yl, int yh);
+void STACK_ARGS rt_add4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_addclamp4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_subclamp4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_revsubclamp4cols (int sx, int yl, int yh);
 
-extern void (*rt_map4cols)(int sx, int yl, int yh);
+void STACK_ARGS rt_tlate4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_tlateadd4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_tlateaddclamp4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_tlatesubclamp4cols (int sx, int yl, int yh);
+void STACK_ARGS rt_tlaterevsubclamp4cols (int sx, int yl, int yh);
+
+void rt_copy1col_asm (int hx, int sx, int yl, int yh);
+void rt_map1col_asm (int hx, int sx, int yl, int yh);
+
+void STACK_ARGS rt_copy4cols_asm (int sx, int yl, int yh);
+void STACK_ARGS rt_map4cols_asm1 (int sx, int yl, int yh);
+void STACK_ARGS rt_map4cols_asm2 (int sx, int yl, int yh);
+}
+
+extern void (STACK_ARGS *rt_map4cols)(int sx, int yl, int yh);
 
 #ifdef USEASM
 #define rt_copy1col		rt_copy1col_asm
 #define rt_copy4cols	rt_copy4cols_asm
 #define rt_map1col		rt_map1col_asm
+#define rt_shaded4cols	rt_shaded4cols_asm
 #else
 #define rt_copy1col		rt_copy1col_c
 #define rt_copy4cols	rt_copy4cols_c
 #define rt_map1col		rt_map1col_c
+#define rt_shaded4cols	rt_shaded4cols_c
 #endif
 
 void rt_draw4cols (int sx);
diff --git a/src/r_drawt.cpp b/src/r_drawt.cpp
index 5880fa7ce..49e30016c 100644
--- a/src/r_drawt.cpp
+++ b/src/r_drawt.cpp
@@ -102,7 +102,7 @@ void rt_copy1col_c (int hx, int sx, int yl, int yh)
 }
 
 // Copies all four spans to the screen starting at sx.
-void rt_copy4cols_c (int sx, int yl, int yh)
+void STACK_ARGS rt_copy4cols_c (int sx, int yl, int yh)
 {
 	int *source;
 	int *dest;
@@ -170,7 +170,7 @@ void rt_map1col_c (int hx, int sx, int yl, int yh)
 }
 
 // Maps all four spans to the screen starting at sx.
-void rt_map4cols_c (int sx, int yl, int yh)
+void STACK_ARGS rt_map4cols_c (int sx, int yl, int yh)
 {
 	BYTE *colormap;
 	BYTE *source;
@@ -214,63 +214,106 @@ void rt_map4cols_c (int sx, int yl, int yh)
 }
 #endif	/* !USEASM */
 
+void rt_Translate1col(const BYTE *translation, int hx, int yl, int yh)
+{
+	int count = yh - yl + 1;
+	BYTE *source = &dc_temp[yl*4 + hx];
+
+	// Things we do to hit the compiler's optimizer with a clue bat:
+	// 1. Parallelism is explicitly spelled out by using a separate
+	//    C instruction for each assembly instruction. GCC lets me
+	//    have four temporaries, but VC++ spills to the stack with
+	//    more than two. Two is probably optimal, anyway.
+	// 2. The results of the translation lookups are explicitly
+	//    stored in byte-sized variables. This causes the VC++ code
+	//    to use byte mov instructions in most cases; for apparently
+	//    random reasons, it will use movzx for some places. GCC
+	//    ignores this and uses movzx always.
+
+	// Do 8 rows at a time.
+	for (int count8 = count >> 3; count8; --count8)
+	{
+		int c0, c1;
+		BYTE b0, b1;
+
+		c0 = source[0];			c1 = source[4];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[0] = b0;			source[4] = b1;
+
+		c0 = source[8];			c1 = source[12];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[8] = b0;			source[12] = b1;
+
+		c0 = source[16];		c1 = source[20];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[16] = b0;		source[20] = b1;
+
+		c0 = source[24];		c1 = source[28];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[28] = b0;		source[28] = b1;
+
+		source += 32;
+	}
+	// Finish by doing 1 row at a time.
+	for (count &= 7; count; --count, source++)
+	{
+		source[0] = translation[source[0]];
+	}
+}
+
+void rt_Translate4cols(const BYTE *translation, int yl, int yh)
+{
+	int count = yh - yl + 1;
+	BYTE *source = &dc_temp[yl*4];
+	int c0, c1;
+	BYTE b0, b1;
+
+	// Do 2 rows at a time.
+	for (int count8 = count >> 1; count8; --count8)
+	{
+		c0 = source[0];			c1 = source[1];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[0] = b0;			source[1] = b1;
+
+		c0 = source[2];			c1 = source[3];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[2] = b0;			source[3] = b1;
+
+		c0 = source[4];			c1 = source[5];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[4] = b0;			source[5] = b1;
+
+		c0 = source[6];			c1 = source[7];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[6] = b0;			source[7] = b1;
+
+		source += 8;
+	}
+	// Do the final row if count was odd.
+	if (count & 1)
+	{
+		c0 = source[0];			c1 = source[1];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[0] = b0;			source[1] = b1;
+
+		c0 = source[2];			c1 = source[3];
+		b0 = translation[c0];	b1 = translation[c1];
+		source[2] = b0;			source[3] = b1;
+	}
+}
+
 // Translates one span at hx to the screen at sx.
 void rt_tlate1col (int hx, int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	translation = dc_translation;
-	colormap = dc_colormap;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4 + hx];
-	pitch = dc_pitch;
-
-	do {
-		*dest = colormap[translation[*source]];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate1col(dc_translation, hx, yl, yh);
+	rt_map1col(hx, sx, yl, yh);
 }
 
 // Translates all four spans to the screen starting at sx.
-void rt_tlate4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_tlate4cols (int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	translation = dc_translation;
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	colormap = dc_colormap;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4];
-	pitch = dc_pitch;
-	
-	do {
-		dest[0] = colormap[translation[source[0]]];
-		dest[1] = colormap[translation[source[1]]];
-		dest[2] = colormap[translation[source[2]]];
-		dest[3] = colormap[translation[source[3]]];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate4cols(dc_translation, yl, yh);
+	rt_map4cols(sx, yl, yh);
 }
 
 // Adds one span at hx to the screen at sx without clamping.
@@ -308,7 +351,7 @@ void rt_add1col (int hx, int sx, int yl, int yh)
 }
 
 // Adds all four spans to the screen starting at sx without clamping.
-void rt_add4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_add4cols (int sx, int yl, int yh)
 {
 	BYTE *colormap;
 	BYTE *source;
@@ -366,95 +409,15 @@ void rt_add4cols (int sx, int yl, int yh)
 // Translates and adds one span at hx to the screen at sx without clamping.
 void rt_tlateadd1col (int hx, int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	translation = dc_translation;
-	colormap = dc_colormap;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4 + hx];
-	pitch = dc_pitch;
-
-	do {
-		DWORD fg = colormap[translation[*source]];
-		DWORD bg = *dest;
-
-		fg = fg2rgb[fg];
-		bg = bg2rgb[bg];
-		fg = (fg+bg) | 0x1f07c1f;
-		*dest = RGB32k[0][0][fg & (fg>>15)];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate1col(dc_translation, hx, yl, yh);
+	rt_add1col(hx, sx, yl, yh);
 }
 
 // Translates and adds all four spans to the screen starting at sx without clamping.
-void rt_tlateadd4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_tlateadd4cols (int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	translation = dc_translation;
-	colormap = dc_colormap;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4];
-	pitch = dc_pitch;
-	
-	do {
-		DWORD fg = colormap[translation[source[0]]];
-		DWORD bg = dest[0];
-		fg = fg2rgb[fg];
-		bg = bg2rgb[bg];
-		fg = (fg+bg) | 0x1f07c1f;
-		dest[0] = RGB32k[0][0][fg & (fg>>15)];
-
-		fg = colormap[translation[source[1]]];
-		bg = dest[1];
-		fg = fg2rgb[fg];
-		bg = bg2rgb[bg];
-		fg = (fg+bg) | 0x1f07c1f;
-		dest[1] = RGB32k[0][0][fg & (fg>>15)];
-
-
-		fg = colormap[translation[source[2]]];
-		bg = dest[2];
-		fg = fg2rgb[fg];
-		bg = bg2rgb[bg];
-		fg = (fg+bg) | 0x1f07c1f;
-		dest[2] = RGB32k[0][0][fg & (fg>>15)];
-
-		fg = colormap[translation[source[3]]];
-		bg = dest[3];
-		fg = fg2rgb[fg];
-		bg = bg2rgb[bg];
-		fg = (fg+bg) | 0x1f07c1f;
-		dest[3] = RGB32k[0][0][fg & (fg>>15)];
-
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate4cols(dc_translation, yl, yh);
+	rt_add4cols(sx, yl, yh);
 }
 
 // Shades one span at hx to the screen at sx.
@@ -489,9 +452,8 @@ void rt_shaded1col (int hx, int sx, int yl, int yh)
 }
 
 // Shades all four spans to the screen starting at sx.
-void rt_shaded4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_shaded4cols_c (int sx, int yl, int yh)
 {
-	BYTE fill;
 	DWORD *fgstart;
 	BYTE *colormap;
 	BYTE *source;
@@ -509,66 +471,73 @@ void rt_shaded4cols (int sx, int yl, int yh)
 	dest = ylookup[yl] + sx + dc_destorg;
 	source = &dc_temp[yl*4];
 	pitch = dc_pitch;
-	{
-		DWORD val = fgstart[64<<8] | 0x1f07c1f;
-		fill = RGB32k[0][0][val & (val>>15)];
-	}
-	
+
+	// 107.1, 108.4, 118.2/117.7, 119.4
 	do {
-		DWORD val = colormap[source[0]];
-		DWORD fg;
-		if (val < 64)
-		{
-			fg = fgstart[val<<8];
-			val = (Col2RGB8[64-val][dest[0]] + fg) | 0x1f07c1f;
-			dest[0] = RGB32k[0][0][val & (val>>15)];
-		}
-		else
-		{
-			dest[0] = fill;
-		}
+		DWORD val;
+		
+		val = colormap[source[0]];
+		val = (Col2RGB8[64-val][dest[0]] + fgstart[val<<8]) | 0x1f07c1f;
+		dest[0] = RGB32k[0][0][val & (val>>15)];
 
 		val = colormap[source[1]];
-		if (val < 64)
-		{
-			fg = fgstart[val<<8];
-			val = (Col2RGB8[64-val][dest[1]] + fg) | 0x1f07c1f;
-			dest[1] = RGB32k[0][0][val & (val>>15)];
-		}
-		else
-		{
-			dest[1] = fill;
-		}
+		val = (Col2RGB8[64-val][dest[1]] + fgstart[val<<8]) | 0x1f07c1f;
+		dest[1] = RGB32k[0][0][val & (val>>15)];
 
 		val = colormap[source[2]];
-		if (val < 64)
-		{
-			fg = fgstart[val<<8];
-			val = (Col2RGB8[64-val][dest[2]] + fg) | 0x1f07c1f;
-			dest[2] = RGB32k[0][0][val & (val>>15)];
-		}
-		else
-		{
-			dest[2] = fill;
-		}
+		val = (Col2RGB8[64-val][dest[2]] + fgstart[val<<8]) | 0x1f07c1f;
+		dest[2] = RGB32k[0][0][val & (val>>15)];
 
 		val = colormap[source[3]];
-		if (val < 64)
-		{
-			fg = fgstart[val<<8];
-			val = (Col2RGB8[64-val][dest[3]] + fg) | 0x1f07c1f;
-			dest[3] = RGB32k[0][0][val & (val>>15)];
-		}
-		else
-		{
-			dest[3] = fill;
-		}
+		val = (Col2RGB8[64-val][dest[3]] + fgstart[val<<8]) | 0x1f07c1f;
+		dest[3] = RGB32k[0][0][val & (val>>15)];
 
 		source += 4;
 		dest += pitch;
 	} while (--count);
 }
 
+#if 0
+static DWORD t_fgstart[1];
+static BYTE t_colormap[1];
+
+void STACK_ARGS rt_shaded4cols_t (int sx, int yl, int yh)
+{
+	BYTE *source;
+	BYTE *dest;
+	int count;
+
+	count = yh-yl;
+	if (count < 0)
+		return;
+	count++;
+
+	dest = ylookup[yl] + sx + dc_destorg;
+	source = &dc_temp[yl*4];
+
+	do {
+		DWORD val, val2;
+		
+		val = t_colormap[source[0]];
+		val2 = t_colormap[source[1]];
+		val = (Col2RGB8[64-val][dest[0]] + t_fgstart[val<<8]) | 0x1f07c1f;
+		val2 = (Col2RGB8[64-val2][dest[1]] + t_fgstart[val2<<8]) | 0x1f07c1f;
+		dest[0] = RGB32k[0][0][val & (val>>15)];
+		dest[1] = RGB32k[0][0][val2 & (val2>>15)];
+
+		val = t_colormap[source[2]];
+		val2 = t_colormap[source[3]];
+		val = (Col2RGB8[64-val][dest[2]] + t_fgstart[val<<8]) | 0x1f07c1f;
+		val2 = (Col2RGB8[64-val2][dest[3]] + t_fgstart[val2<<8]) | 0x1f07c1f;
+		dest[2] = RGB32k[0][0][val & (val>>15)];
+		dest[3] = RGB32k[0][0][val2 & (val2>>15)];
+
+		source += 4;
+		dest += 320;
+	} while (--count);
+}
+#endif
+
 // Adds one span at hx to the screen at sx with clamping.
 void rt_addclamp1col (int hx, int sx, int yl, int yh)
 {
@@ -606,7 +575,7 @@ void rt_addclamp1col (int hx, int sx, int yl, int yh)
 }
 
 // Adds all four spans to the screen starting at sx with clamping.
-void rt_addclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_addclamp4cols (int sx, int yl, int yh)
 {
 	BYTE *colormap;
 	BYTE *source;
@@ -672,105 +641,15 @@ void rt_addclamp4cols (int sx, int yl, int yh)
 // Translates and adds one span at hx to the screen at sx with clamping.
 void rt_tlateaddclamp1col (int hx, int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4 + hx];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = fg2rgb[colormap[translation[*source]]] + bg2rgb[*dest];
-		DWORD b = a;
-
-		a |= 0x01f07c1f;
-		b &= 0x40100400;
-		a &= 0x3fffffff;
-		b = b - (b >> 5);
-		a |= b;
-		*dest = RGB32k[0][0][(a>>15) & a];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate1col(dc_translation, hx, yl, yh);
+	rt_addclamp1col(hx, sx, yl, yh);
 }
 
 // Translates and adds all four spans to the screen starting at sx with clamping.
-void rt_tlateaddclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_tlateaddclamp4cols (int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = fg2rgb[colormap[translation[source[0]]]] + bg2rgb[dest[0]];
-		DWORD b = a;
-
-		a |= 0x01f07c1f;
-		b &= 0x40100400;
-		a &= 0x3fffffff;
-		b = b - (b >> 5);
-		a |= b;
-		dest[0] = RGB32k[0][0][(a>>15) & a];
-
-		a = fg2rgb[colormap[translation[source[1]]]] + bg2rgb[dest[1]];
-		b = a;
-		a |= 0x01f07c1f;
-		b &= 0x40100400;
-		a &= 0x3fffffff;
-		b = b - (b >> 5);
-		a |= b;
-		dest[1] = RGB32k[0][0][(a>>15) & a];
-
-		a = fg2rgb[colormap[translation[source[2]]]] + bg2rgb[dest[2]];
-		b = a;
-		a |= 0x01f07c1f;
-		b &= 0x40100400;
-		a &= 0x3fffffff;
-		b = b - (b >> 5);
-		a |= b;
-		dest[2] = RGB32k[0][0][(a>>15) & a];
-
-		a = fg2rgb[colormap[translation[source[3]]]] + bg2rgb[dest[3]];
-		b = a;
-		a |= 0x01f07c1f;
-		b &= 0x40100400;
-		a &= 0x3fffffff;
-		b = b - (b >> 5);
-		a |= b;
-		dest[3] = RGB32k[0][0][(a>>15) & a];
-
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate4cols(dc_translation, yl, yh);
+	rt_addclamp4cols(sx, yl, yh);
 }
 
 // Subtracts one span at hx to the screen at sx with clamping.
@@ -809,7 +688,7 @@ void rt_subclamp1col (int hx, int sx, int yl, int yh)
 }
 
 // Subtracts all four spans to the screen starting at sx with clamping.
-void rt_subclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_subclamp4cols (int sx, int yl, int yh)
 {
 	BYTE *colormap;
 	BYTE *source;
@@ -871,100 +750,15 @@ void rt_subclamp4cols (int sx, int yl, int yh)
 // Translates and subtracts one span at hx to the screen at sx with clamping.
 void rt_tlatesubclamp1col (int hx, int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4 + hx];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = (fg2rgb[colormap[translation[*source]]] | 0x40100400) - bg2rgb[*dest];
-		DWORD b = a;
-
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		*dest = RGB32k[0][0][(a>>15) & a];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate1col(dc_translation, hx, yl, yh);
+	rt_subclamp1col(hx, sx, yl, yh);
 }
 
 // Translates and subtracts all four spans to the screen starting at sx with clamping.
-void rt_tlatesubclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_tlatesubclamp4cols (int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = (fg2rgb[colormap[translation[source[0]]]] | 0x40100400) - bg2rgb[dest[0]];
-		DWORD b = a;
-
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[0] = RGB32k[0][0][(a>>15) & a];
-
-		a = (fg2rgb[colormap[translation[source[1]]]] | 0x40100400) - bg2rgb[dest[1]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[1] = RGB32k[0][0][(a>>15) & a];
-
-		a = (fg2rgb[colormap[translation[source[2]]]] | 0x40100400) - bg2rgb[dest[2]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[2] = RGB32k[0][0][(a>>15) & a];
-
-		a = (fg2rgb[colormap[translation[source[3]]]] | 0x40100400) - bg2rgb[dest[3]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[3] = RGB32k[0][0][(a>>15) & a];
-
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate4cols(dc_translation, yl, yh);
+	rt_subclamp4cols(sx, yl, yh);
 }
 
 // Subtracts one span at hx from the screen at sx with clamping.
@@ -1003,7 +797,7 @@ void rt_revsubclamp1col (int hx, int sx, int yl, int yh)
 }
 
 // Subtracts all four spans from the screen starting at sx with clamping.
-void rt_revsubclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_revsubclamp4cols (int sx, int yl, int yh)
 {
 	BYTE *colormap;
 	BYTE *source;
@@ -1065,104 +859,19 @@ void rt_revsubclamp4cols (int sx, int yl, int yh)
 // Translates and subtracts one span at hx from the screen at sx with clamping.
 void rt_tlaterevsubclamp1col (int hx, int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4 + hx];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = (bg2rgb[dest[0]] | 0x40100400) - fg2rgb[colormap[translation[source[0]]]];
-		DWORD b = a;
-
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		*dest = RGB32k[0][0][(a>>15) & a];
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate1col(dc_translation, hx, yl, yh);
+	rt_revsubclamp1col(hx, sx, yl, yh);
 }
 
 // Translates and subtracts all four spans from the screen starting at sx with clamping.
-void rt_tlaterevsubclamp4cols (int sx, int yl, int yh)
+void STACK_ARGS rt_tlaterevsubclamp4cols (int sx, int yl, int yh)
 {
-	BYTE *translation;
-	BYTE *colormap;
-	BYTE *source;
-	BYTE *dest;
-	int count;
-	int pitch;
-
-	count = yh-yl;
-	if (count < 0)
-		return;
-	count++;
-
-	DWORD *fg2rgb = dc_srcblend;
-	DWORD *bg2rgb = dc_destblend;
-	dest = ylookup[yl] + sx + dc_destorg;
-	source = &dc_temp[yl*4];
-	pitch = dc_pitch;
-	colormap = dc_colormap;
-	translation = dc_translation;
-
-	do {
-		DWORD a = (bg2rgb[dest[0]] | 0x40100400) - fg2rgb[colormap[translation[source[0]]]];
-		DWORD b = a;
-
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[0] = RGB32k[0][0][(a>>15) & a];
-
-		a = (bg2rgb[dest[1]] | 0x40100400) - fg2rgb[colormap[translation[source[1]]]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[1] = RGB32k[0][0][(a>>15) & a];
-
-		a = (bg2rgb[dest[2]] | 0x40100400) - fg2rgb[colormap[translation[source[2]]]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[2] = RGB32k[0][0][(a>>15) & a];
-
-		a = (bg2rgb[dest[3]] | 0x40100400) - fg2rgb[colormap[translation[source[3]]]];
-		b = a;
-		b &= 0x40100400;
-		b = b - (b >> 5);
-		a &= b;
-		a |= 0x01f07c1f;
-		dest[3] = RGB32k[0][0][(a>>15) & a];
-
-		source += 4;
-		dest += pitch;
-	} while (--count);
+	rt_Translate4cols(dc_translation, yl, yh);
+	rt_revsubclamp4cols(sx, yl, yh);
 }
 
 // Copies all spans in all four columns to the screen starting at sx.
-// sx should be longword-aligned.
+// sx should be dword-aligned.
 void rt_draw4cols (int sx)
 {
 	int x, bad;
diff --git a/src/r_main.cpp b/src/r_main.cpp
index bd15a101a..9ca9c4231 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -205,7 +205,7 @@ void (*spanfunc) (void);
 void (*hcolfunc_pre) (void);
 void (*hcolfunc_post1) (int hx, int sx, int yl, int yh);
 void (*hcolfunc_post2) (int hx, int sx, int yl, int yh);
-void (*hcolfunc_post4) (int sx, int yl, int yh);
+void (STACK_ARGS *hcolfunc_post4) (int sx, int yl, int yh);
 
 cycle_t WallCycles, PlaneCycles, MaskedCycles, WallScanCycles;
 
diff --git a/src/r_main.h b/src/r_main.h
index abecbd971..fdb3b636f 100644
--- a/src/r_main.h
+++ b/src/r_main.h
@@ -147,7 +147,7 @@ extern void 			(*spanfunc) (void);
 extern void (*hcolfunc_pre) (void);
 extern void (*hcolfunc_post1) (int hx, int sx, int yl, int yh);
 extern void (*hcolfunc_post2) (int hx, int sx, int yl, int yh);
-extern void (*hcolfunc_post4) (int sx, int yl, int yh);
+extern void (STACK_ARGS *hcolfunc_post4) (int sx, int yl, int yh);
 
 
 //
diff --git a/src/tmap.nas b/src/tmap.nas
index e03df7163..259f5e6a6 100644
--- a/src/tmap.nas
+++ b/src/tmap.nas
@@ -55,6 +55,7 @@ EXTERN CPU
 
 EXTERN dc_pitch
 EXTERN dc_colormap
+EXTERN dc_color
 EXTERN dc_iscale
 EXTERN dc_texturefrac
 EXTERN dc_source
@@ -68,6 +69,9 @@ EXTERN dc_destorg
 EXTERN dc_ctspan
 EXTERN dc_temp
 
+EXTERN Col2RGB8
+EXTERN RGB32k
+
 EXTERN ds_xstep
 EXTERN ds_ystep
 EXTERN ds_colormap
@@ -94,6 +98,7 @@ EXTERN _CPU
 
 EXTERN _dc_pitch
 EXTERN _dc_colormap
+EXTERN _dc_color
 EXTERN _dc_iscale
 EXTERN _dc_texturefrac
 EXTERN _dc_source
@@ -107,6 +112,9 @@ EXTERN _dc_destorg
 EXTERN _dc_ctspan
 EXTERN _dc_temp
 
+EXTERN _Col2RGB8
+EXTERN _RGB32k
+
 EXTERN _ds_xstep
 EXTERN _ds_ystep
 EXTERN _ds_colormap
@@ -131,6 +139,7 @@ GLOBAL _ds_curcolormap
 
 %define dc_pitch	_dc_pitch
 %define dc_colormap	_dc_colormap
+%define dc_color	_dc_color
 %define dc_iscale	_dc_iscale
 %define dc_texturefrac	_dc_texturefrac
 %define dc_source	_dc_source
@@ -141,6 +150,9 @@ GLOBAL _ds_curcolormap
 %define dc_dest		_dc_dest
 %define dc_destorg	_dc_destorg
 
+%define Col2RGB8	_Col2RGB8
+%define RGB32k		_RGB32k
+
 %define dc_ctspan	_dc_ctspan
 %define dc_temp		_dc_temp
 
@@ -1476,10 +1488,121 @@ _rt_map4cols_asm2:
 	pop	ebx
 	ret	4
 
+	align 16
+
+GLOBAL rt_shaded4cols_asm
+GLOBAL _rt_shaded4cols_asm
+
+rt_shaded4cols_asm:
+_rt_shaded4cols_asm:
+		mov		ecx,[esp+8]
+		push	ebp
+		mov		ebp,[esp+16]
+		sub		ebp,ecx
+		js		near s4nil
+		mov		eax,[ylookup+ecx*4]
+		add		eax,[dc_destorg]				; eax = destination
+		push	ebx
+		push	esi
+		inc		ebp								; ebp = count
+		add		eax,[esp+16]
+		push	edi
+		lea		esi,[dc_temp+ecx*4]				; esi = source
+
+		align	16
+
+s4loop:	movzx	edx,byte [esi]
+		movzx	ecx,byte [esi+1]
+s4cm1:	movzx	edx,byte [SPACEFILLER4+edx]		; colormap
+s4cm2:	movzx	edi,byte [SPACEFILLER4+ecx]		; colormap
+		shl		edx,8
+		movzx	ebx,byte [eax]
+		shl		edi,8
+		movzx	ecx,byte [eax+1]
+		sub		ebx,edx
+		sub		ecx,edi
+		mov		ebx,[Col2RGB8+0x10000+ebx*4]
+		mov		ecx,[Col2RGB8+0x10000+ecx*4]
+s4fg1:	add		ebx,[SPACEFILLER4+edx*4]
+s4fg2:	add		ecx,[SPACEFILLER4+edi*4]
+		or		ebx,0x1f07c1f
+		or		ecx,0x1f07c1f
+		mov		edx,ebx
+		shr		ebx,15
+		mov		edi,ecx
+		shr		ecx,15
+		and		edx,ebx
+		and		ecx,edi
+		mov		bl,[RGB32k+edx]
+		movzx	edx,byte [esi+2]
+		mov		bh,[RGB32k+ecx]
+		movzx	ecx,byte [esi+3]
+		mov		[eax],bl
+		mov		[eax+1],bh
+
+s4cm3:	movzx	edx,byte [SPACEFILLER4+edx]		; colormap
+s4cm4:	movzx	edi,byte [SPACEFILLER4+ecx]		; colormap
+		shl		edx,8
+		movzx	ebx,byte [eax+2]
+		shl		edi,8
+		movzx	ecx,byte [eax+3]
+		sub		ebx,edx
+		sub		ecx,edi
+		mov		ebx,[Col2RGB8+0x10000+ebx*4]
+		mov		ecx,[Col2RGB8+0x10000+ecx*4]
+s4fg3:	add		ebx,[SPACEFILLER4+edx*4]
+s4fg4:	add		ecx,[SPACEFILLER4+edi*4]
+		or		ebx,0x1f07c1f
+		or		ecx,0x1f07c1f
+		mov		edx,ebx
+		shr		ebx,15
+		mov		edi,ecx
+		shr		ecx,15
+		and		edx,ebx
+		and		ecx,edi
+s4p:	add		eax,320							; pitch
+		add		esi,4
+		mov		bl,[RGB32k+edx]
+		mov		bh,[RGB32k+ecx]
+s4p2:	mov		[eax-320+2],bl
+s4p3:	mov		[eax-320+3],bh
+		dec		ebp
+		jne		s4loop
+
+		pop		edi
+		pop		esi
+		pop		ebx
+s4nil:	pop		ebp
+		ret
+
+		align 16
+
 ;************************
 
 	SECTION .text
 
+GLOBAL	R_SetupShadedCol
+GLOBAL	_R_SetupShadedCol
+GLOBAL	@R_SetupShadedCol@0
+
+# Patch the values of dc_colormap and dc_color into the shaded column drawer.
+
+R_SetupShadedCol:
+_R_SetupShadedCol:
+@R_SetupShadedCol@0:
+		mov		eax,[dc_colormap]
+		mov		[s4cm1+3],eax
+		mov		[s4cm2+3],eax
+		mov		[s4cm3+3],eax
+		mov		[s4cm4+3],eax
+		mov		eax,[dc_color]
+		lea		eax,[Col2RGB8+eax*4]
+		mov		[s4fg1+3],eax
+		mov		[s4fg2+3],eax
+		mov		[s4fg3+3],eax
+		mov		[s4fg4+3],eax
+		ret
+
 EXTERN setvlinebpl_
 EXTERN setpitch3
 
@@ -1490,11 +1613,19 @@ GLOBAL	ASM_PatchPitch
 ASM_PatchPitch:
 _ASM_PatchPitch:
 @ASM_PatchPitch@0:
-	mov	eax,[dc_pitch]
-	mov	[rdcp1+2],eax
-	mov	[rdcp2+2],eax
-	mov	[rdcp3+2],eax
-	call	setpitch3
-	jmp	setvlinebpl_
+		mov		eax,[dc_pitch]
+		mov		[rdcp1+2],eax
+		mov		[rdcp2+2],eax
+		mov		[rdcp3+2],eax
+		mov		[s4p+1],eax
+		mov		ecx,eax
+		neg		ecx
+		inc		ecx
+		inc		ecx
+		mov		[s4p2+2],ecx
+		inc		ecx
+		mov		[s4p3+2],ecx
+		call	setpitch3
+		jmp		setvlinebpl_