Add screen wipe segue.

Backported from https://github.com/next-hack/nRF52840Doom

GBADoom.pro

@@ -177,6 +177,6 @@ win32-msvc* {
 #    LIBS += $$PWD/codeprophet.lib
 #    QMAKE_CXXFLAGS += /GH /Gh
 #    QMAKE_CFLAGS += /GH /Gh
-     QMAKE_CFLAGS += /fsanitize=address
-     QMAKE_CXXFLAGS += /fsanitize=address
+#     QMAKE_CFLAGS += /fsanitize=address
+#     QMAKE_CXXFLAGS += /fsanitize=address
 }

Makefile

@@ -27,13 +27,25 @@ INCLUDES	:= include
 DATA		:= data
 MUSIC		:= music
 
+#---------------------------------------------------------------------------------
+# Disable LTO for IWRAM
+#---------------------------------------------------------------------------------
+%.iwram.o: %.iwram.cpp
+	$(SILENTMSG) $(notdir $<)
+	$(SILENTCMD)$(CXX) -MMD -MP -MF $(DEPSDIR)/$*.iwram.d $(CXXFLAGS) -fno-lto -marm -c $< -o $@ $(ERROR_FILTER)
+
+#---------------------------------------------------------------------------------
+%.iwram.o: %.iwram.c
+	$(SILENTMSG) $(notdir $<)
+	$(SILENTCMD)$(CC) -MMD -MP -MF $(DEPSDIR)/$*.iwram.d $(CFLAGS) -fno-lto -marm -c $< -o $@ $(ERROR_FILTER)
+
 #---------------------------------------------------------------------------------
 # options for code generation
 #---------------------------------------------------------------------------------
 ARCH	:=	-mthumb -mthumb-interwork
 
-CFLAGS	:=	-g -Wall -O3 -fgcse-after-reload\
-		-mcpu=arm7tdmi -mtune=arm7tdmi\
+CFLAGS	:=	-g -Wall -O3 -fgcse-after-reload -gdwarf-4\
+                -mcpu=arm7tdmi -mtune=arm7tdmi -flto\
 		$(ARCH)
 
 CFLAGS	+=	$(INCLUDE)

include/f_wipe.h

@@ -38,6 +38,7 @@
  * SCREEN WIPE PACKAGE
  */
 
+void wipe_initMelt();
 int wipe_ScreenWipe (int ticks);
 int wipe_StartScreen(void);
 int wipe_EndScreen  (void);

include/global_data.h

@@ -163,7 +163,7 @@ boolean         castdeath;
 //f_wipe.c
 //******************************************************************************
 
-int wipe_tick;
+short y_lookup[SCREENWIDTH];
 
 //******************************************************************************
 //g_game.c

include/i_system_e32.h

@@ -34,6 +34,8 @@ void I_Quit_e32();
 
 unsigned short* I_GetBackBuffer();
 
+unsigned short* I_GetFrontBuffer();
+
 #ifdef __cplusplus
 }
 #endif

source/d_main.c

@@ -135,6 +135,8 @@ static void D_Wipe(void)
 	boolean done;
 	int wipestart = I_GetTime () - 1;
 
+    wipe_initMelt();
+
 	do
 	{
 		int nowtime, tics;
@@ -147,7 +149,7 @@ static void D_Wipe(void)
 		wipestart = nowtime;
 		done = wipe_ScreenWipe(tics);
 
-		I_UpdateNoBlit();
+        I_UpdateNoBlit();
 		M_Drawer();                   // menu is drawn even on top of wipes
 
 	} while (!done);

source/f_wipe.c

@@ -32,6 +32,8 @@
  *-----------------------------------------------------------------------------
  */
 
+//Most of this code is backported from https://github.com/next-hack/nRF52840Doom
+
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -44,6 +46,8 @@
 #include "m_random.h"
 #include "f_wipe.h"
 #include "global_data.h"
+#include "i_system_e32.h"
+
 
 #ifdef __arm__
     #include <gba.h>
@@ -55,59 +59,101 @@
 
 int wipe_StartScreen(void)
 {
-    _g->wipe_tick = 0;
     return 0;
 }
 
 int wipe_EndScreen(void)
 {
-    _g->wipe_tick = 0;
     return 0;
 }
 
-// killough 3/5/98: reformatted and cleaned up
-int wipe_ScreenWipe(int ticks)
+// oh man, why aren't you commenting anything ?
+// 2021-08-08 next-hack: commented and modified to use the dual buffer.
+static int wipe_doMelt(int ticks)
 {
-    unsigned int wipepos;
+    boolean done = true;
 
-    //Do a pageflip on the 16th tick.
-    boolean pageflip = (_g->wipe_tick < 16) &&  (_g->wipe_tick + ticks >= 16);
+    unsigned short* backbuffer = I_GetBackBuffer();
+    unsigned short* frontbuffer = I_GetFrontBuffer();
 
-    _g->wipe_tick += ticks;
-
-    int wipeticks = _g->wipe_tick;
-
-    if(wipeticks >= 32)
-    {
-        wipeticks = 32;
-        wipepos = 0;
-    }
-    else if(wipeticks < 16)
-    {
-        wipepos = wipeticks;
-    }
-    else //16->31
+    while (ticks--)
     {
-        wipepos = 31 - wipeticks;
+        for (int i = 0; i < SCREENWIDTH; i++)
+        {
+            if (_g->y_lookup[i] < 0)
+            {
+                _g->y_lookup[i]++;
+                done = false;
+                continue;
+            }
+
+            // scroll down columns, which are still visible
+            if (_g->y_lookup[i] < SCREENHEIGHT)
+            {
+                /* cph 2001/07/29 -
+                 *  The original melt rate was 8 pixels/sec, i.e. 25 frames to melt
+                 *  the whole screen, so make the melt rate depend on SCREENHEIGHT
+                 *  so it takes no longer in high res
+                 */
+                int dy = (_g->y_lookup[i] < 16) ? _g->y_lookup[i] + 1 : SCREENHEIGHT / 25;
+                // At most dy shall be so that the column is shifted by SCREENHEIGHT (i.e. just
+                // invisible)
+                if (_g->y_lookup[i] + dy >= SCREENHEIGHT)
+                    dy = SCREENHEIGHT - _g->y_lookup[i];
+
+                unsigned short* s = &frontbuffer[i] + ((SCREENHEIGHT - dy - 1) * SCREENPITCH);
+
+                unsigned short* d = &frontbuffer[i] + ((SCREENHEIGHT - 1) * SCREENPITCH);
+
+                // scroll down the column. Of course we need to copy from the bottom... up to
+                // SCREENHEIGHT - yLookup - dy
+
+                for (int j = SCREENHEIGHT - _g->y_lookup[i] - dy; j; j--)
+                {
+                    *d = *s;
+                    d += -SCREENPITCH;
+                    s += -SCREENPITCH;
+                }
+
+                // copy new screen. We need to copy only between y_lookup and + dy y_lookup
+                s = &backbuffer[i] +  _g->y_lookup[i] * SCREENPITCH;
+                d = &frontbuffer[i] + _g->y_lookup[i] * SCREENPITCH;
+
+                for (int j = 0 ; j < dy; j++)
+                {
+                    *d = *s;
+                    d += SCREENPITCH;
+                    s += SCREENPITCH;
+                }
+
+                _g->y_lookup[i] += dy;
+                done = false;
+            }
+        }
     }
+    return done;
+}
 
-#ifdef __arm__
-    REG_BLDCNT = 0xc4;
-    REG_BLDY = wipepos;
-
-    VBlankIntrWait();
-#endif
+void wipe_initMelt()
+{
+    // setup initial column positions (y<0 => not ready to scroll yet)
+    _g->y_lookup[0] = -(M_Random() % 16);
+    for (int i = 1; i < SCREENWIDTH; i++)
+    {
+        int r = (M_Random() % 3) - 1;
 
-    if(pageflip)
-         I_FinishUpdate();
+        _g->y_lookup[i] = _g->y_lookup[i - 1] + r;
 
-    if(wipeticks >= 32)
-    {
-#ifdef __arm__
-        REG_BLDCNT = 0;
-#endif
-        return 1;
+        if (_g->y_lookup[i] > 0)
+            _g->y_lookup[i] = 0;
+        else if (_g->y_lookup[i] == -16)
+            _g->y_lookup[i] = -15;
     }
+}
 
-    return 0;
+
+int wipe_ScreenWipe(int ticks)
+{
+    // do a piece of wipe-in
+    return wipe_doMelt(ticks);
 }

source/i_system_e32.cpp

@@ -38,6 +38,7 @@ unsigned char* thearray = NULL;
 int thesize;
 
 unsigned short backbuffer[120 *160];
+unsigned short frontbuffer[120 *160];
 
 //**************************************************************************************
 
@@ -82,6 +83,11 @@ unsigned short* I_GetBackBuffer()
     return &backbuffer[0];
 }
 
+unsigned short* I_GetFrontBuffer()
+{
+    return &frontbuffer[0];
+}
+
 //**************************************************************************************
 
 void I_CreateWindow_e32()

source/i_system_gba.cpp

@@ -248,6 +248,16 @@ unsigned short* I_GetBackBuffer()
 
 //**************************************************************************************
 
+unsigned short* I_GetFrontBuffer()
+{
+    if(REG_DISPCNT & DCNT_PAGE)
+        return (unsigned short*)VID_PAGE2;
+
+    return (unsigned short*)VID_PAGE1;
+}
+
+//**************************************************************************************
+
 void I_CreateWindow_e32()
 {