From 913ac3558234fb137c604362b9e861529d74d1d1 Mon Sep 17 00:00:00 2001
From: Lephenixnoir <sebastien.michelland@protonmail.com>
Date: Thu, 30 Sep 2021 11:44:07 +0200
Subject: [PATCH] Emulate PRAM and the secondary VRAM layout

---
 cgdoom/cgdoom.c     | 15 ++++++++-------
 cgdoom/i_system.c   | 14 ++------------
 src-cg/platform.h   |  9 +++++++++
 src-sdl2/emul.c     |  4 +++-
 src-sdl2/platform.h | 10 ++++++++++
 5 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/cgdoom/cgdoom.c b/cgdoom/cgdoom.c
index 8a3b0de..58df167 100644
--- a/cgdoom/cgdoom.c
+++ b/cgdoom/cgdoom.c
@@ -524,7 +524,7 @@ int main(void)
 	if (!strcmp(wads[choice].name, "doomu4.wad"))
 		CGD_SingleEpisodeUltimate = 4;
 
-	uintptr_t secondary_vram = ((uintptr_t)GetSecondaryVRAMAddress() | 3) + 1;
+	uintptr_t secondary_vram = ((uintptr_t)GetSecondaryVRAMAddress() + 3) & -4;
 	SaveVRAMBuffer = (void *)secondary_vram;
 
 	/* fx-CG 50 / Graph 90+E: RAM starts at 0x0c000000 in physical memory */
@@ -534,6 +534,8 @@ int main(void)
 	if(CGD_2MBLineMemory)
 		CGD_2MBLineMemory = FindZeroedMemory((void *)0xac200000);
 
+	void *PRAM0_alloc_start = PRAM0_START;
+
 	/* Remember WAD file name for saves and loads */
 	static char wad_name[32] = { 0 };
 	for (int i = 0; wads[choice].name[i] != '.'; i++)
@@ -564,7 +566,7 @@ int main(void)
 		#endif /* FLASH_INDEX */
 
 		time = RTC_GetTicks();
-		gWADMap.mTable = (void *)0xfe200000; /* PRAM0 */
+		gWADMap.mTable = PRAM0_START;
 		int fd = Bfile_OpenFile_OS(wads[choice].path, 0, 0);
 		int size = CreateFileMapping(fd, &gWADMap);
 		Bfile_CloseFile_OS(fd);
@@ -605,13 +607,12 @@ int main(void)
 			GetKey(&key);
 		}
 
-		/* Initialize the PRAM allocator */
-		void *PRAM0_start = (void *)0xfe200000;
-		void *PRAM0_end   = (void *)0xfe228000;
-		PRAM0_start += gWADMap.miItemCount * sizeof(FileMappingItem);
-		CGD_PRAM_Init(PRAM0_start, PRAM0_end);
+		PRAM0_alloc_start += gWADMap.miItemCount * sizeof(FileMappingItem);
 	}
 
+	/* Initialize the PRAM allocator */
+	CGD_PRAM_Init(PRAM0_alloc_start, PRAM0_END);
+
 	memset(VRAM, 0, WIDTH*HEIGHT*2);
 	D_DoomMain();
 
diff --git a/cgdoom/i_system.c b/cgdoom/i_system.c
index 361baed..3795afb 100644
--- a/cgdoom/i_system.c
+++ b/cgdoom/i_system.c
@@ -67,16 +67,6 @@ byte* I_ZoneBase (int*	size, int i)
     return NULL;
 }
 
-byte *I_ScreenBase(int screen)
-{
-    if (screen == 0 || screen == 1 || screen == 2 || screen == 3)
-        return malloc(320 * 200);
-    if (screen == 4)
-        return malloc(320 * 32);
-
-    return NULL;
-}
-
 #else /* fx-CG build */
 
 /* On the calculator, scrap every possible bit of RAM */
@@ -114,6 +104,8 @@ byte* I_ZoneBase (int*  size, int i)
     return NULL;
 }
 
+#endif
+
 byte *I_ScreenBase(int screen)
 {
     /* The primary/secondary VRAM covers 384*216*2 = 162 kiB:
@@ -141,8 +133,6 @@ byte *I_ScreenBase(int screen)
     return NULL;
 }
 
-#endif
-
 //
 // I_Init
 // Initialize machine state
diff --git a/src-cg/platform.h b/src-cg/platform.h
index b89747d..7bcf8b4 100644
--- a/src-cg/platform.h
+++ b/src-cg/platform.h
@@ -50,6 +50,15 @@
    disable.) */
 #define CGDOOM_DIRECT_R61524
 
+//---
+// Memory layout
+//---
+
+/* PRAM0 is an area of SPU2 memory that supports only 32-bit access. It is used
+   for the file mapping and some allocations; see <cgdoom-alloc.h>. */
+#define PRAM0_START ((void *)0xfe200000)
+#define PRAM0_END   ((void *)0xfe228000)
+
 //---
 // Memory distribution
 //---
diff --git a/src-sdl2/emul.c b/src-sdl2/emul.c
index 949d682..3b4d2e0 100644
--- a/src-sdl2/emul.c
+++ b/src-sdl2/emul.c
@@ -8,6 +8,8 @@
 SDL_Window *window = NULL;
 SDL_Surface *VRAM_RGB888 = NULL;
 
+char _PRAM0[160*1024];
+
 /* Rendering system emulation. */
 
 uint16_t _VRAM[WIDTH * HEIGHT];
@@ -334,7 +336,7 @@ int Bfile_FindNext(int fd, uint16_t *found, void *fileinfo0)
 		return -16;
 
 	const char *name = glob->gl_pathv[*pos];
-	Bfile_StrToName_ncpy(found, name, strlen(name));
+	Bfile_StrToName_ncpy(found, name, strlen(name)+1);
 	(*pos)++;
 
 	Bfile_FileInfo *fileinfo = fileinfo0;
diff --git a/src-sdl2/platform.h b/src-sdl2/platform.h
index 50a22a3..389651a 100644
--- a/src-sdl2/platform.h
+++ b/src-sdl2/platform.h
@@ -8,6 +8,16 @@
 #include <stdint.h>
 #include "keyboard.hpp"
 
+//---
+// Memory layout
+//---
+
+extern char _PRAM0[160*1024];
+#define PRAM0_START ((void *)_PRAM0)
+#define PRAM0_END ((void *)_PRAM0 + sizeof _PRAM0)
+
+#define CGDOOM_SCREENS_BASE SaveVRAMBuffer
+
 //---
 // fx-CG-specific functions not defined on emulator
 //---