From 049834434967f33d137fdc91d2d36641379cf252 Mon Sep 17 00:00:00 2001
From: Lephe <sebastien.michelland@protonmail.com>
Date: Sun, 31 May 2020 22:26:30 +0200
Subject: [PATCH] periodic check of SH3 compatibility

---
 include/gint/hardware.h |  5 +++--
 src/core/exch.c         | 14 ++++++++++++--
 src/core/exch.s         | 22 ++++++++++++++++++++--
 src/core/hardware.c     |  2 +-
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/include/gint/hardware.h b/include/gint/hardware.h
index 18d1d1f..f77ee4c 100644
--- a/include/gint/hardware.h
+++ b/include/gint/hardware.h
@@ -24,7 +24,8 @@
 extern uint32_t gint[HW_KEYS];
 
 /* MPU detection macros, with a faster version on fx-CG 50 and a generic
-   dual-platform version for libraries. */
+   dual-platform version for libraries.
+   Warning: this macro is also used hardcoded in exch.s. */
 
 #if defined(FX9860G) || (!defined(FX9860G) && !defined(FXCG50))
 #define isSH3() (gint[HWMPU] & 1)
@@ -75,7 +76,7 @@ void hw_detect(void);
 #define HWMPU_UNKNOWN  0
 /* Used on original fx-9860G, SH-3-based */
 #define HWMPU_SH7337   1
-/* Used on recent fx-9860G derivates such as the fx-9750G II, and also on the
+/* Used on recent fx-9860G derivatives such as the fx-9750G II, and also on the
    fx-CG 10/20/50. SH-4A-based */
 #define HWMPU_SH7305   2
 /* Used on the fx-9860G II, SH-3-based */
diff --git a/src/core/exch.c b/src/core/exch.c
index 54d044c..a1e9871 100644
--- a/src/core/exch.c
+++ b/src/core/exch.c
@@ -11,8 +11,18 @@
 /* gint_panic_default(): Default panic handler */
 GNORETURN static void gint_default_panic(GUNUSED uint32_t code)
 {
-	uint32_t TEA = *(volatile uint32_t *)0xff00000c;
-	uint32_t TRA = *(volatile uint32_t *)0xff000020 >> 2;
+	uint32_t TEA, TRA;
+
+	if(isSH3())
+	{
+		TEA = *(volatile uint32_t *)0xfffffffc;
+		TRA = *(volatile uint32_t *)0xffffffd0 >> 2;
+	}
+	else
+	{
+		TEA = *(volatile uint32_t *)0xff00000c;
+		TRA = *(volatile uint32_t *)0xff000020 >> 2;
+	}
 
 	uint32_t PC;
 	__asm__("stc spc, %0" : "=r"(PC));
diff --git a/src/core/exch.s b/src/core/exch.s
index a2f8105..c5539db 100644
--- a/src/core/exch.s
+++ b/src/core/exch.s
@@ -4,10 +4,21 @@
 
 _gint_exch_tlbh:
 	sts.l	pr, @-r15
+	stc.l	gbr, @-r15
+	sts.l	mach, @-r15
+	sts.l	macl, @-r15
 	mov.l	r8, @-r15
 
-	mov.l	.expevt, r8
+	/* Get the first word of the gint hardware array (HWMPU). If it has the
+	   last bit set, we're SH3 */
+	mov.l	.gint, r0
+	mov.l	@r0, r0
+	tst	#1, r0
+	mov.l	.expevt_sh4, r8
+	bt	catch
+	mov.l	.expevt_sh3, r8
 
+catch:
 	/* Panic if the catcher is NULL */
 	mov.l	.catcher, r0
 	mov.l	@r0, r0
@@ -39,14 +50,21 @@ panic:
 
 end:
 	mov.l	@r15+, r8
+	lds.l	@r15+, macl
+	lds.l	@r15+, mach
+	ldc.l	@r15+, gbr
 	lds.l	@r15+, pr
 	rte
 	nop
 
 .align 4
 
-.expevt:
+.gint:
+	.long	_gint
+.expevt_sh4:
 	.long	0xff000024
+.expevt_sh3:
+	.long	0xffffffd4
 .catcher:
 	.long	_gint_exc_catcher
 .panic:
diff --git a/src/core/hardware.c b/src/core/hardware.c
index 1e75a39..6457a9e 100644
--- a/src/core/hardware.c
+++ b/src/core/hardware.c
@@ -101,7 +101,7 @@ void hw_detect(void)
 	/* Will be detected later on */
 	gint[HWURAM] = -1;
 	/* Traditionally 4 MiB, Graph 35+E II has 8 MiB */
-	gint[HWROM]  = (gint[HWCALC] == HWCALC_G35PE2) ? (4 << 20) : (8 << 20);
+	gint[HWROM]  = (gint[HWCALC] == HWCALC_G35PE2) ? (8 << 20) : (4 << 20);
 }
 
 #endif /* FX9860G and platform-agnostic */