exc: add exception handlers, use them in the DMA

This change introduces exception handlers that default to a fatal error
with an on-screen description of the exception and some debugging
information.

It also adds the dprint() function as a definitely-needed helper and
removes bootlog_unmapped() by using the exception handler for the fatal
error display. (Also printf() is now required in all gint add-ins; this
is sad, but space is not as much of a constraint as debugging.)

Finally, the exception handler is used to handle an interrupt which is
an exception in practice, the DMA address error. On fx-CG 50, additional
DMA-related information is displayed on the screen. This is left out on
fx-9860G as there is not enough space.

TODO

@@ -1,7 +1,7 @@
 Crucial, missing things.
 ! core:      the four basic memory functions
-! core:      build an exception handler and a TLB miss handler
-! core:      gint_switch() (driver contexts on stack; arbitrary code?)
+! core:      gint_switch() with driver contexts on stack and arbitrary code
+! core:      use gint_switch() to handle TLB misses
 ! bopti:     fxcg50 version
 ! syscalls:  fxcg50 BFile calls
 
@@ -10,10 +10,11 @@ Tests to run.
 * topti:     all charsets
 
 Complementary elements on existing code.
+* gray:      find good values for more models than the Graph 35+E II
 * render:    get rid of GINT_NEED_VRAM and #define vram gint_vram if you need
 * dma:       dma_memcpy() and dma_memset(), possibly requiring alignment
-* core:      use topti in the error message for missing mappings
 * core:      find the #ifdef FX9860G|FXCG50 that have a cross-platform def
+* core:      try to leave add-in without reset in case of fatal exception
 * topti:     support Unicode fonts
 * hardware:  fill in the HWMEM_FITTLB flag
 * keyboard:  think of extended functions

fx9860g.ld

@@ -55,6 +55,10 @@ SECTIONS
 	} > rom
 
 	.text : {
+		_gint_exch_tlbh_start = . ;
+		*(.gint.exch_tlbh);
+		_gint_exch_tlbh_size = ABSOLUTE(. - _gint_exch_tlbh_start);
+
 		*(.text .text.*)
 		*(C P)
 	} > rom

fxcg50.ld

@@ -49,6 +49,10 @@ SECTIONS
 		*(.dtors .dtors.*)
 		_etors = . ;
 
+		_gint_exch_tlbh_start = . ;
+		*(.gint.exch_tlbh);
+		_gint_exch_tlbh_size = ABSOLUTE(. - _gint_exch_tlbh_start);
+
 		*(.text .text.*)
 	} > rom
 

include/core/bootlog.h

@@ -11,12 +11,6 @@
    Called when RAM sections have been wiped and copied */
 void bootlog_loaded(void);
 
-/* bootlog_unmapped() - ROM mapping stage failed
-   Called if not enough ROM pages have been mapped.
-   @rom  Amount of mapped ROM, in bytes
-   @size Minimum mapping required */
-void bootlog_unmapped(int rom, int size);
-
 /* bootlog_mapped() - ROM mapping stage
    Called after all ROM pages have been traversed. All of them may not have
    been mapped.
@@ -37,7 +31,6 @@ void bootlog_driver_summary(void);
 /* All these functions are enabled only if GINT_BOOT_LOG is defined */
 #ifndef GINT_BOOT_LOG
   #define bootlog_loaded(...)
-  #define bootlog_unmapped(...)
   #define bootlog_mapped(...)
   #define bootlog_kernel(...)
   #define bootlog_driver(...)

include/core/setup.h

@@ -20,4 +20,12 @@
    Returns the previous VBR address. */
 uint32_t gint_setvbr(uint32_t vbr, void (*configure)(void));
 
+/* gint_exch_tlbh(): Exception and TLB miss handler */
+void gint_exch_tlbh(void);
+
+/* gint_inth_7705(): SH7705 exception handler */
+void gint_inth_7705(void);
+/* gint_inth_7305(): SH7305 exception handler */
+void gint_inth_7305(void);
+
 #endif /* GINT_CORE_SETUP */

include/gint/display.h

@@ -199,6 +199,11 @@ void dsize(const char *str, font_t const * font, int *w, int *h);
            fxcg50:  Any R5G6B5 color, or C_NONE */
 void dtext(int x, int y, const char *str, int fg, int bg);
 
+/* dprint(): Display a formatted string
+   Much like dtext(), but accepts printf-like formats with arguments. See
+   <gint/std/stdio.h> for a detailed view of what this format supports. */
+void dprint(int x, int y, int fg, int bg, char const *format, ...);
+
 //---
 //	Image rendering (bopti)
 //---

include/gint/dma.h

@@ -79,4 +79,19 @@ void dma_transfer_noint(int channel, dma_size_t size, uint blocks,
 	void const *src, dma_address_t src_mode,
 	void *dst, dma_address_t dst_mode);
 
+//---
+//	DMA-based memory manipulation functions
+//---
+
+/* dma_memset(): Fast 32-aligned memset
+   This function is your typical memset, except that the destination and size
+   must be 32-aligned, and that the pattern is 4 bytes instead of one. It is
+   replicated to 32 bytes then used to fill the destination area. This 4-byte
+   fixed size may be lifted in future versions.
+
+   @dst      Destination address (32-aligned)
+   @pattern  4-byte pattern to fill @dst
+   @size     Sie of destination area (32-aligned) */
+void *dma_memset(void *dst, uint32_t pattern, size_t size);
+
 #endif /* GINT_DMA */

include/gint/exc.h

@@ -0,0 +1,21 @@
+//---
+//	gint:exc - Exception handling
+//
+//	This small module is used to display exceptions and configure when the
+//	exception handler displays these messages. This is for advanced users
+//	only!
+//---
+
+#ifndef GINT_EXC
+#define GINT_EXC
+
+/* gint_exc(): Exception handler fatal error message
+   Displays a full-screen fatal error message from an exception event code.
+   Some custom event codes are also used for library failure. This function is
+   typically called by exception handlers and returns after a dupdate_noint().
+   You probably want to soft-lock or quit the add-in after calling it. */
+void gint_exc(uint32_t code);
+
+/* TODO: Add functions to disable fatal errors for some exceptions */
+
+#endif /* GINT_EXC */

src/core/bootlog.c

@@ -117,14 +117,6 @@ void bootlog_mapped(int rom, GUNUSED int ram)
 	dupdate();
 }
 
-/* bootlog_unmapped() - ROM mapping stage failure */
-void bootlog_unmapped(int rom, int size)
-{
-	print(1, 6, "MMU: add-in too large");
-	print(1, 7, "%8x < %8x", rom, size);
-	dupdate();
-}
-
 /* bootlog_kernel() - gint loading stage */
 void bootlog_kernel(void)
 {

src/core/exch.S

@@ -1,26 +0,0 @@
-/*
-**	gint:core:exch - Exception handlers
-*/
-
-.global _exch_entry_7305
-
-#ifdef FX9860G
-.global _exch_entry_7705
-#endif
-
-.section .gint.blocks, "ax"
-.align 4
-
-/* SH7305-TYPE DEBUG EXCEPTION HANDLER */
-
-_exch_entry_7705:
-_exch_entry_7305:
-	mov.l	1f, r0
-	mov.l	@r0, r4
-
-	rte
-	nop
-
-	.zero 20
-
-1:	.long	0xff000024

src/core/exch.c

@@ -0,0 +1,98 @@
+#define GINT_NEED_VRAM
+#include <gint/display.h>
+#include <gint/exc.h>
+#include <gint/defs/attributes.h>
+
+#define dprint(x, y, ...) dprint(x, y, C_BLACK, C_NONE, __VA_ARGS__)
+#define dtext(x, y, str)  dtext (x, y, str, C_BLACK, C_NONE)
+
+/* gint_exc(): Exception handler fatal error message */
+void gint_exc(GUNUSED uint32_t code)
+{
+	uint32_t TEA = *(volatile uint32_t *)0xff00000c;
+	uint32_t TRA = *(volatile uint32_t *)0xff000020 >> 2;
+
+	uint32_t PC;
+	__asm__("stc spc, %0" : "=r"(PC));
+
+	dfont(NULL);
+	dclear(C_WHITE);
+
+	#ifdef FX9860G
+	dtext(1, 0, "Exception! (SysERROR)");
+	for(int i = 0; i < 32; i++) vram[i] = ~vram[i];
+
+	char const *name = "";
+	if(code == 0x040) name = "TLB miss read";
+	if(code == 0x060) name = "TLB miss write";
+	if(code == 0x0e0) name = "Read address error";
+	if(code == 0x100) name = "Write address error";
+	if(code == 0x160) name = "Unconditional trap";
+	if(code == 0x180) name = "Illegal instruction";
+	if(code == 0x1a0) name = "Illegal delay slot";
+
+	/* Custom gint codes for convenience */
+	if(code == 0x1020) name = "DMA address error";
+	if(code == 0x1040) name = "Add-in too large";
+
+	if(name[0]) dtext(1, 9, name);
+	else dprint(1, 9, "%03x", code);
+
+	dprint(1, 17, " PC :%08x", PC);
+	dprint(1, 25, "TEA :%08x", TEA);
+	dprint(1, 33, "TRA :%08x", TRA);
+
+	dtext(1, 49, "The add-in crashed.");
+	dtext(1, 57, "Please reset the calc");
+	#endif
+
+	#ifdef FXCG50
+	dtext(6, 3, "An exception occured! (System ERROR)");
+
+	uint32_t *long_vram = (void *)vram;
+	for(int i = 0; i < 198 * 16; i++) long_vram[i] = ~long_vram[i];
+
+	char const *name = "";
+	if(code == 0x040) name = "TLB miss (nonexisting address) on read";
+	if(code == 0x060) name = "TLB miss (nonexisting address) on write";
+	if(code == 0x0e0) name = "Read address error (probably alignment)";
+	if(code == 0x100) name = "Write address error (probably alignment)";
+	if(code == 0x160) name = "Unconditional trap";
+	if(code == 0x180) name = "Illegal instruction";
+	if(code == 0x1a0) name = "Illegal delay slot instruction";
+
+	/* Custom gint codes for convenience */
+	if(code == 0x1020) name = "DMA address error";
+	if(code == 0x1040) name = "Add-in not fully mapped (too large)";
+
+	dprint(6, 25, "%03x %s", code, name);
+
+	dtext(6, 45, "PC");
+	dprint(38, 45, "= %08x", PC);
+	dtext(261, 45, "(Error location)");
+
+	dtext(6, 60, "TEA");
+	dprint(38, 60, "= %08x", TEA);
+	dtext(234, 60, "(Offending address)");
+
+	dtext(6, 75, "TRA");
+	dprint(38, 75, "= %#x", TRA);
+	dtext(281, 75, "(Trap number)");
+
+	dtext(6, 95,  "An unrecoverable error ocurred in the add-in.");
+	dtext(6, 108, "Please press the RESET button to restart the");
+	dtext(6, 121, "calculator.");
+	#endif
+
+	dupdate_noint();
+}
+
+/* gint_exch_tlbh(): Exception and TLB miss handler */
+__attribute__((interrupt_handler)) GSECTION(".gint.exch_tlbh") GALIGNED(4)
+void gint_exch_tlbh(void)
+{
+	uint32_t EXPEVT = *(volatile uint32_t *)0xff000024;
+
+	gint_exc(EXPEVT);
+	while(1);
+}

src/core/inth.S

@@ -5,10 +5,10 @@
 **	blocks depending on its configuration.
 */
 
-.global _inth_entry_7305
+.global _gint_inth_7305
 
 #ifdef FX9860G
-.global _inth_entry_7705
+.global _gint_inth_7705
 #endif
 
 .section .gint.blocks, "ax"
@@ -36,7 +36,7 @@
 /* SH7305-TYPE DEBUG INTERRUPT HANDLER - 26 BYTES */
 
 #if 0
-_inth_entry_7305:
+_gint_inth_7305:
 	mov.l	1f, r0
 	mov.l	@r0, r4
 
@@ -56,7 +56,7 @@ _inth_entry_7305:
 
 /* SH7305-TYPE INTERRUPT HANDLER ENTRY - 20 BYTES */
 
-_inth_entry_7305:
+_gint_inth_7305:
 	/* Get the event code from the INTEVT register */
 	mov.l	1f, r0
 	mov.l	@r0, r0
@@ -78,7 +78,7 @@ _inth_entry_7305:
 
 /* SH7705-TYPE INTERRUT HANDLER ENTRY - 32 BYTES */
 
-_inth_entry_7705:
+_gint_inth_7705:
 	/* Get the event code from the INTEVT2 register */
 	mov.l	1f, r0
 	mov.l	@r0, r0		/* r0 = old_code */

src/core/setup.c

@@ -13,6 +13,8 @@
 extern char gint_vbr;
 /* System's VBR address */
 GBSS static uint32_t system_vbr;
+/* Size of exception and TLB handler */
+extern char gint_exch_tlbh_size;
 /* Driver table */
 extern gint_driver_t bdrv, edrv;
 
@@ -67,11 +69,13 @@ static void lock(void)
 void gint_install(void)
 {
 	/* VBR address, provided by the linker script */
-	uint32_t vbr = (uint32_t)&gint_vbr;
+	void *vbr = (void *)&gint_vbr;
 
 	/* Event handler entry points */
-	void *exch_entry;
-	void *inth_entry;
+	void *inth_entry = isSH3() ? gint_inth_7705 : gint_inth_7305;
+
+	/* Size of the exception and TLB handlers */
+	uint32_t exch_tlbh_size = (uint32_t)&gint_exch_tlbh_size;
 
 	/* First save the hardware configuration. This step is crucial because
 	   we don't want the system to find out about us directly manipulating
@@ -79,28 +83,12 @@ void gint_install(void)
 	gint_ctx_save(&sys_ctx);
 
 	/* Load the event handler entry points into memory */
-	/* TODO: Load an exception handler and a TLB miss handler */
-
-	if(isSH3())
-	{
-		extern void exch_entry_7705(void);
-		extern void inth_entry_7705(void);
-		exch_entry = exch_entry_7705;
-		inth_entry = inth_entry_7705;
-	}
-	else
-	{
-		extern void exch_entry_7305(void);
-		extern void inth_entry_7305(void);
-		exch_entry = exch_entry_7305;
-		inth_entry = inth_entry_7305;
-	}
-
-	memcpy((void *)(vbr + 0x100), exch_entry, 32);
-	memcpy((void *)(vbr + 0x600), inth_entry, 32);
+	memcpy(vbr + 0x100, gint_exch_tlbh, exch_tlbh_size);
+	memcpy(vbr + 0x400, gint_exch_tlbh, exch_tlbh_size);
+	memcpy(vbr + 0x600, inth_entry, 32);
 
 	/* Time to switch VBR and roll! */
-	system_vbr = gint_setvbr(vbr, lock);
+	system_vbr = gint_setvbr((uint32_t)vbr, lock);
 }
 
 /* unlock() - unlock interrupts, restoring system settings */

src/core/start.c

@@ -9,6 +9,7 @@
 #include <gint/drivers.h>
 #include <gint/gint.h>
 #include <gint/hardware.h>
+#include <gint/exc.h>
 
 /* Symbols provided by the linker script. For sections:
    - l* represents the load address (source address in ROM)
@@ -135,7 +136,7 @@ int start(int isappli, int optnum)
 	/* Cancel add-in execution if not all pages are mapped */
 	if(rom < (uint32_t)&srom)
 	{
-		bootlog_unmapped(rom, (uint32_t)&srom);
+		gint_exc(0x1040);
 		while(1);
 		return 1;
 	}

src/dma/dma.c

@@ -6,6 +6,8 @@
 #include <gint/dma.h>
 #include <gint/drivers.h>
 #include <gint/clock.h>
+#include <gint/display.h>
+#include <gint/exc.h>
 
 #define DMA SH7305_DMA
 #define INTC SH7305_INTC
@@ -150,6 +152,34 @@ void dma_transfer_noint(int channel, dma_size_t size, uint blocks,
 	DMA.OR.NMIF = 0;
 }
 
+//---
+//	Address error handler
+//---
+
+/* gint_dma_ae(): DMA Address Error handler */
+void gint_dma_ae(void)
+{
+	gint_exc(0x1020);
+
+	#ifdef FXCG50
+	dprint(6, 141, C_BLACK, C_NONE,
+		"SAR0: %08x   DAR0: %08x   TCR0: %08x",
+		DMA.DMA0.SAR, DMA.DMA0.DAR, DMA.DMA0.TCR);
+	dprint(6, 154, C_BLACK, C_NONE,
+		"CHCR0: %08x", DMA.DMA0.CHCR);
+	dprint(6, 167, C_BLACK, C_NONE,
+		"SAR1: %08x   DAR1: %08x   TCR1: %08x",
+		DMA.DMA1.SAR, DMA.DMA1.DAR, DMA.DMA1.TCR);
+	dprint(6, 180, C_BLACK, C_NONE,
+		"CHCR1: %08x", DMA.DMA1.CHCR);
+	dprint(6, 193, C_BLACK, C_NONE,
+		"DMAOR: %04x", DMA.OR);
+	dupdate_noint();
+	#endif
+
+	while(1);
+}
+
 //---
 //	Initialization
 //---

src/dma/inth.s

@@ -46,4 +46,4 @@ _inth_dma_ae:
 
 	.zero 14
 
-1:	.long _dma_address_error
+1:	.long _gint_dma_ae

src/dma/memset.c

@@ -1,11 +1,12 @@
 #include <gint/dma.h>
 
-/* dma_memset(): Fast memset for highly-aligned addresses */
-void dma_memset(void *dst, uint32_t l, size_t size)
+/* dma_memset(): Fast 32-aligned memset */
+void *dma_memset(void *dst, uint32_t l, size_t size)
 {
 	/* TODO: Use a proper IL memory allocation scheme */
 	uint32_t *IL = (void *)0xe5200000;
 	for(int i = 0; i < 8; i++) IL[i] = l;
 
 	dma_transfer_noint(1, DMA_32B, size >> 5, IL, DMA_FIXED, dst, DMA_INC);
+	return dst;
 }

src/render/dprint.c

@@ -0,0 +1,15 @@
+#include <gint/display.h>
+#include <gint/std/stdio.h>
+
+/* dprint(): Display a formatted string */
+void dprint(int x, int y, int fg, int bg, char const *format, ...)
+{
+	char str[256];
+	va_list args;
+
+	va_start(args, format);
+	vsnprintf(str, 256, format, args);
+	va_end(args);
+
+	dtext(x, y, str, fg, bg);
+}