From d5e434c684f36200fca0f4505bc4885b9fdd9c66 Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Fri, 20 Nov 2020 02:34:07 -0800
Subject: [PATCH] GB: Fix CGB-to-DMG switchover

---
 .../misc/boot_hwio-C/xbaseline_0000.png         | Bin 846 -> 827 bytes
 src/gb/gb.c                                     |  11 ++++++-----
 src/gb/io.c                                     |   6 +++++-
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/cinema/gb/mooneye-gb/misc/boot_hwio-C/xbaseline_0000.png b/cinema/gb/mooneye-gb/misc/boot_hwio-C/xbaseline_0000.png
index cb37cb619c559ad7defcd227f00231c8a4e60760..fb836d344a281e22ec87159031e82cd3d3f6b310 100644
GIT binary patch
delta 549
zcmV+=0^0q~2D=83B!2=)L_t(|obB4%lA<sG08y~`|6gVvoQf%O58!A|pC?zDaA{%H
zu<rZ5uIs+<OC&tAu50{!yjXZCJXskhET0`AT}3*0I)1vktfBQbhpLQo*wf0$o#R|$
zOII1MFC6ZAxzgkMx=Zhj(tuZ)8~nLDhqp`V&nv@DzrE%>!hZ_F4)m-nEPvRz(m2n5
z#(!0E_`~##6*M<;XuX|V^&BnTo^<)r^V!2Yv{OU2@F;t&t_Vl%@F%5lF4_9#l{R(N
zdb4lbp)<I0cyB+0M^_WlW>1dn^*pE_@xuaV@(iuFDV)J4Hz~f<zrj|2Ic!Jze^2%j
zeTiEKpA#R4>3>bS^@Byp`_=^T&M;T`zAe^}M|%-{GXujJ7|y_O28J^*oPpsC47V-S
zdClxBUOJx`7RZhhztl4?+cVGFKNDOZr*o+9_4`|Nb|>R`q0%f$&+JNRez)@5Y;)G7
ze_C_sd7jsV|MNk1?k|15w0!e6kIo}|)nr5ec2d>O;D3s{&y2gr!FLTBAF|Hh5pm)C
zt|lBW(M#d#+Ihc6cASa%-R9@Gt1jK=hx%|%7sB~H7_RXtI{VU_Z~UC*_uwV`(9!&H
zBYylR_ZH3ZQ}j0XJ@s4oJ@|E3C32rVgCFs4RsUzV|Br2{eoy_tTa-2A(?2EYB)<p4
n85qvMaFdq;p_8BjWETAZi`EV9etPDc00000NkvXXu0mjf)!QO(

delta 563
zcmV-30?hrp2F?bMB!3l2L_t(|obB4tcB(KG08w!9|G&(Auq)+~<Rk&KGR}T#Ee3Fa
zs$pK&b)M&SU8jxo$UM*6$G3~6KcxqQanka|5%N{!gXiPtt1B8>Z*!<%oZX%VBM0O3
zY{rl!UuC|&X1UtW@w#hAMs2{W92@+(JG;ZB_Vi%b`0%=Xe}5lo1!)I*R*;sT{@<C}
zIL}|V&#KuyF+Z@9=0*;!w{xqWqvhL^FJF87^5ZqOq@Rk{>Ogwcc2B8|bMhrlgO3h)
z)q0Bu?$8<h{<>2-gP%sPSGAL)cs)<zSA4g?nLI=5ZAxeG$xYf`>fd0A|D3iX|KC%*
zL|@{igCDbf9e)mQQv7aox6D=k;G%I~e{zjI>3&<RA&>SVx-$dA85qvMa0Z4mFr0zm
z3=FqS;k;&X7OyscIW&2kFP|3ZnP=^v3696<9O}M)zKbsI<aS=DHjC0TyHcCq4ZfRg
z&eHTxYYsim^E=`H{GmAamp@)xzImHR=PP^Fm+$@CNq-fc!GTww8Lu7(-!*Bx$vS^W
z#D(*_I$(c^o+?+@&ig%z;~bdZZN88Do>TB7rwify91PcZ7hU|*;roi;tah{5SA7ni
zcmG_6Zc)C`EiA9T*ZN~E$3Cat%R6s!`!v6IRZ{o4c)r5+G4R-aSH;`yueur+EmQb8
z^#gBF?hO~z9i6whuWvuV@%$W<VFJXHpaMr0_Ye027Vd~!4gLTC002ovPDHLkV1hqL
BEA0RP

diff --git a/src/gb/gb.c b/src/gb/gb.c
index 9c13b795b..998505c04 100644
--- a/src/gb/gb.c
+++ b/src/gb/gb.c
@@ -489,11 +489,6 @@ void GBSkipBIOS(struct GB* gb) {
 	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
 	int nextDiv = 0;
 
-	if (gb->model >= GB_MODEL_CGB && !(cart->cgb & 0x80)) {
-		gb->model = GB_MODEL_DMG;
-		GBVideoDisableCGB(&gb->video);
-	}
-
 	switch (gb->model) {
 	case GB_MODEL_AUTODETECT: // Silence warnings
 		gb->model = GB_MODEL_DMG;
@@ -559,6 +554,12 @@ void GBSkipBIOS(struct GB* gb) {
 			cpu->e = 0x08;
 			cpu->l = 0x7C;
 			gb->timer.internalDiv = 0x260;
+			gb->model = GB_MODEL_DMG;
+			gb->memory.io[GB_REG_KEY1] = 0xFF;
+			gb->memory.io[GB_REG_BCPS] = 0x88; // Faked writing 4 BG palette entries
+			gb->memory.io[GB_REG_OCPS] = 0x90; // Faked writing 8 OBJ palette entries
+			gb->memory.io[GB_REG_SVBK] = 0xFF;
+			GBVideoDisableCGB(&gb->video);
 		}
 		nextDiv = 0xC;
 		break;
diff --git a/src/gb/io.c b/src/gb/io.c
index e46e50412..612e4d819 100644
--- a/src/gb/io.c
+++ b/src/gb/io.c
@@ -214,7 +214,11 @@ void GBIOReset(struct GB* gb) {
 		GBIOWrite(gb, GB_REG_HDMA3, 0xFF);
 		GBIOWrite(gb, GB_REG_HDMA4, 0xFF);
 		gb->memory.io[GB_REG_HDMA5] = 0xFF;
-	} else if (gb->model & GB_MODEL_SGB) {
+	} else {
+		memset(&gb->memory.io[GB_REG_KEY0], 0xFF, GB_REG_PCM34 - GB_REG_KEY0);
+	}
+
+	if (gb->model & GB_MODEL_SGB) {
 		GBIOWrite(gb, GB_REG_JOYP, 0xFF);
 	}
 	GBIOWrite(gb, GB_REG_IE, 0x00);