From a8c2fdb172772d88d157d5edbcd0d493244b0873 Mon Sep 17 00:00:00 2001
From: viciious <vluchits@gmail.com>
Date: Fri, 27 Sep 2024 22:19:21 +0300
Subject: [PATCH] Support recording demos to SRAM

---
 d_main.c  | 11 ++++++++---
 doomdef.h | 11 +++++++++++
 g_game.c  | 18 +++++++++++++++---
 m_main.c  |  5 +++++
 marsnew.c | 30 ++++++++++++++++++++++++++++++
 5 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/d_main.c b/d_main.c
index 2bda46126..f3beb364a 100644
--- a/d_main.c
+++ b/d_main.c
@@ -431,7 +431,14 @@ int MiniLoop ( void (*start)(void),  void (*stop)(void)
 		gamevbls += vblsinframe;
 
 		if (demorecording)
-			*demo_p++ = buttons;
+		{
+#ifdef MARS_USE_SRAM_DEMO
+			I_WriteU32SRAM((intptr_t)demo_p, buttons);
+#else
+			*demo_p = buttons;
+#endif
+			demo_p++;
+		}
 		
 		if ((demorecording || demoplayback) && (buttons & BT_PAUSE) )
 		{
@@ -950,8 +957,6 @@ D_printf ("DM_Main\n");
 
 /*	while (1)	RunDemo ("DEMO1"); */
 
-/*G_RecordDemo ();	// set startmap and startskill */
-
 /*	MiniLoop (F_Start, F_Stop, F_Ticker, F_Drawer, UpdateBuffer); */
 
 /*G_InitNew (startskill, startmap, gt_deathmatch, false); */
diff --git a/doomdef.h b/doomdef.h
index 63f8e851b..e1412eb38 100644
--- a/doomdef.h
+++ b/doomdef.h
@@ -26,6 +26,12 @@
 #endif
 #endif
 
+#define MARS_USE_SRAM_DEMO
+#define MARS_SRAM_DEMO_OFS 0x800
+#if defined(MARS_USE_SRAM_DEMO) && !defined(MARS)
+#undef MARS_USE_SRAM_DEMO
+#endif
+
 typedef unsigned short pixel_t;
 
 #ifdef MARS
@@ -1254,6 +1260,11 @@ void I_SetCDFileCache(int length);
 void *I_GetCDFileCache(int length);
 int I_ReadCDDirectory(const char *path);
 
+uint8_t I_ReadSRAM(int offset);
+void I_WriteSRAM(int offset, int val);
+uint32_t I_ReadU32SRAM(int offset);
+void I_WriteU32SRAM(int offset, uint32_t val);
+
 /*================= */
 /*TLS */
 /*================= */
diff --git a/g_game.c b/g_game.c
index 55b734c55..1564ffc8f 100644
--- a/g_game.c
+++ b/g_game.c
@@ -602,6 +602,8 @@ void G_RunGame (void)
 				I_NetStop();
 			if (startsave != -1)
 				G_LoadGame(startsave);
+			else if (demorecording)
+				G_RecordDemo();	// set startmap and startskill
 			else
 				G_InitNew(startskill, startmap, starttype, startsplitscreen);
 			continue;
@@ -733,18 +735,28 @@ int G_PlayDemoPtr (unsigned *demo)
 
 void G_RecordDemo (void)
 {
+#ifdef MARS_USE_SRAM_DEMO
+	demo_p = demobuffer = (void *)MARS_SRAM_DEMO_OFS;
+
+	I_WriteU32SRAM((intptr_t)demo_p, startskill);
+	demo_p++;
+
+	I_WriteU32SRAM((intptr_t)demo_p, startmap);
+	demo_p++;
+#else
 	demo_p = demobuffer = Z_Malloc (0x8000, PU_STATIC);
-	
+
 	*demo_p++ = startskill;
 	*demo_p++ = startmap;
-	
+#endif
+
 	G_InitNew (startskill, startmap, gt_single, false);
 	demorecording = true; 
 	MiniLoop (P_Start, P_Stop, P_Ticker, P_Drawer, P_Update);
 	demorecording = false;
 
 #ifdef MARS
-	I_Error("%d %p", demo_p - demobuffer, demobuffer);
+	I_Error("%d %p", (intptr_t)demo_p - (intptr_t)demobuffer, demobuffer);
 #endif
 
 	D_printf ("w %x,%x",demobuffer,demo_p);
diff --git a/m_main.c b/m_main.c
index 5974630e9..5ab884abb 100644
--- a/m_main.c
+++ b/m_main.c
@@ -398,6 +398,11 @@ int M_Ticker (void)
 			startskill = playerskill;	/* set skill level */
 			starttype = currentplaymode;	/* set play type */
 			startsplitscreen = currentgametype == mi_splitscreen;
+			if ((ticrealbuttons & (BT_Y|BT_MODE)) == (BT_Y|BT_MODE))
+			{
+				// hold Y and MODE to begin recording a demo
+				demorecording = true;
+			}
 			return ga_startnew;		/* done with menu */
 		}
 
diff --git a/marsnew.c b/marsnew.c
index eba55c5b8..23b699520 100644
--- a/marsnew.c
+++ b/marsnew.c
@@ -1262,3 +1262,33 @@ int I_ReadCDDirectory(const char *path)
 {
 	return Mars_MCDReadDirectory(path);
 }
+
+uint8_t I_ReadU8SRAM(int offset)
+{
+	uint8_t c;
+	Mars_ReadSRAM(&c, offset, 1);
+	return c;
+}
+
+void I_WriteU8SRAM(int offset, int val)
+{
+	uint8_t c = val & 0xff;
+	Mars_WriteSRAM(&c, offset, 1);
+}
+
+uint32_t I_ReadU32SRAM(int offset)
+{
+	uint8_t c[4];
+	Mars_ReadSRAM(c, offset, 4);
+	return (c[0] << 24) | (c[1] << 16) | (c[2] << 8) | c[3];
+}
+
+void I_WriteU32SRAM(int offset, uint32_t val)
+{
+	uint8_t c[4];
+	c[0] = (val >> 24) & 0xff;
+	c[1] = (val >> 16) & 0xff;
+	c[2] = (val >>  8) & 0xff;
+	c[3] = (val >>  0) & 0xff;
+	Mars_WriteSRAM(c, offset, 4);
+}