Fixes Gameboy output

* Fixes Gameboy output
* Documentation changes for Gameboy
* Gameboy example now works

3 files changed, 77 insertions, 57 deletions

diff --git a/src/Makefile b/src/Makefile
index 6ac1bdf..baadcb4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -79,14 +79,14 @@ clean:
 alias.o: alias.c global.h basetype.h util.h state.h alias.h
 casm.o: casm.c global.h basetype.h util.h state.h expr.h label.h macro.h \
  cmd.h parse.h codepage.h stack.h listing.h alias.h output.h rawout.h \
- specout.h t64out.h zx81out.h z80.h 6502.h gbcpu.h
+ specout.h t64out.h zx81out.h gbout.h z80.h 6502.h gbcpu.h
 codepage.o: codepage.c global.h basetype.h util.h state.h codepage.h \
  parse.h cmd.h
 expr.o: expr.c global.h basetype.h util.h state.h expr.h label.h
 gbcpu.o: gbcpu.c global.h basetype.h util.h state.h expr.h label.h \
  parse.h cmd.h codepage.h varchar.h gbcpu.h
-gbout.o: gbout.c global.h basetype.h util.h state.h codepage.h parse.h \
- cmd.h gbout.h
+gbout.o: gbout.c global.h basetype.h util.h state.h expr.h codepage.h \
+ parse.h cmd.h gbout.h
 label.o: label.c global.h basetype.h util.h state.h codepage.h parse.h \
  cmd.h stack.h label.h
 listing.o: listing.c global.h basetype.h util.h state.h label.h macro.h \
@@ -94,7 +94,7 @@ listing.o: listing.c global.h basetype.h util.h state.h label.h macro.h \
 macro.o: macro.c global.h basetype.h util.h state.h codepage.h parse.h \
  cmd.h varchar.h macro.h
 output.o: output.c global.h basetype.h util.h state.h output.h parse.h \
- cmd.h rawout.h specout.h t64out.h zx81out.h
+ cmd.h rawout.h specout.h t64out.h zx81out.h gbout.h
 parse.o: parse.c global.h basetype.h util.h state.h codepage.h parse.h \
  cmd.h
 rawout.o: rawout.c global.h basetype.h util.h state.h rawout.h parse.h \
diff --git a/src/example/gb.asm b/src/example/gb.asm
index 10381e9..2f52e0e 100644
--- a/src/example/gb.asm
+++ b/src/example/gb.asm
@@ -1,22 +1,26 @@
+	;
+	; This example is poor, and leaves lots of junk lymg in memory.
+	; Still, it works enough to test
+	;
 	
 	cpu	gameboy
 
 	option	output-file,gb.gb
 	option	output-format,gameboy
 
-	;option	gameboy-irq,vbl,vbl_code
+	option	gameboy-irq,vbl,vbl_code
 
 VRAM	equ	$8000
 SCRN	equ	$9800
 OAM	equ	$fe00
 LCDC	equ	$ff40
 STAT	equ	$ff41
+ISWITCH	equ	$ffff
 BGRDPAL	equ	$ff47
 OBJ0PAL	equ	$ff48
 OBJ1PAL	equ	$ff49
 CURLINE	equ	$ff44
 
-READY	equ	$ff81
 XPOS	equ	$ff82
 
 VBLANK	macro
@@ -39,31 +43,29 @@ VBLANK	macro
 	org	$150
 
 	di
-	xor	a
-	ldh	(READY),a
 	ld	sp,$fffe
 
-	; Set LCD so only sprites show
+	; Switch of display during setup
 	;
 	VBLANK
+	xor	a
+	ld	(LCDC),a
+
+	ld	(XPOS),a
 
-	ld	a,$81
-	ldh	(LCDC),a
-	ld	a,$10
-	ldh	(STAT),a
 	ld	a,$e4
-	ldh	(BGRDPAL),a
 	ldh	(OBJ0PAL),a
 	ldh	(OBJ1PAL),a
 
-	; Copy to VRAM
+	swap	a
+	ldh	(BGRDPAL),a
+
+	; Copy to VRAM and set up
 	;
 	ld	hl,VRAM
 	ld	de,sprite
 	ld	c,16
 
-	VBLANK
-
 .copy
 	ld	a,(de)
 	ld	(hl+),a
@@ -71,12 +73,6 @@ VBLANK	macro
 	dec	c
 	jr	nz,copy
 
-	ld	a,1
-	ldh	(READY),a
-
-	ei
-
-	VBLANK
 
 	; Set sprite numbers
 	;
@@ -92,9 +88,24 @@ VBLANK	macro
 	ld	(OAM+7),a
 	ld	(OAM+11),a
 
+	; Set LCD back on
+	;
+	ld	a,$83
+	ldh	(LCDC),a
+
+	; Activate VBL
+	;
+	ld	a,1
+	ldh	(ISWITCH),a
+
+	ei
+
 .idle
-	VBLANK
+	halt
+	nop
+	jr	idle
 
+vbl_code:
 	ldh	a,(XPOS)
 	inc	a
 	ldh	(XPOS),a
@@ -110,23 +121,6 @@ VBLANK	macro
 	ld	(OAM+8),a
 	ld	(OAM+9),a
 
-	jr	idle
-
-vbl_code:
-	ldh	a,(READY)
-	or	a
-	jr	z,finish
-
-	ldh	a,(XPOS)
-	inc	a
-	ldh	(XPOS),a
-	ld	(OAM),a
-	ld	(OAM+1),a
-	xor	a
-	ld	(OAM+2),a
-	ld	(OAM+3),a
-
-.finish
 	reti
 
 sprite:
@@ -141,3 +135,21 @@ sprite:
 	defb	$ff,$ff
 	defb	$00,00
 
+	;
+	; Assembly checks
+	;
+	stop
+	swap	a
+	swap	b
+	swap	c
+	swap	d
+	swap	e
+	swap	h
+	swap	l
+	swap	(hl)
+	ld	a,(hl+)
+	ld	a,(hli)
+	ldi	a,(hl)
+	ld	a,(hl-)
+	ld	a,(hld)
+	ldd	a,(hl)
diff --git a/src/gbout.c b/src/gbout.c
index 24e365a..71547f9 100644
--- a/src/gbout.c
+++ b/src/gbout.c
@@ -41,7 +41,6 @@ enum option_t
     OPT_SUPER,
     OPT_CART_RAM,
     OPT_CART_TYPE,
-    OPT_RST,
     OPT_IRQ
 };
 
@@ -51,7 +50,7 @@ static const ValueTable option_set[] =
     {"gameboy-color",           OPT_COLOUR},
     {"gameboy-super",           OPT_SUPER},
     {"gameboy-cart-ram",        OPT_CART_RAM},
-    {"gameboy-cart-type",       OPT_CART_RAM},
+    {"gameboy-cart-type",       OPT_CART_TYPE},
     {"gameboy-irq",             OPT_IRQ},
     {NULL}
 };
@@ -193,8 +192,8 @@ int GBOutput(const char *filename, const char *filename_bank,
     int f;
     int offset;
     int rom_size;
-    unsigned global_csum = 0;
-    unsigned hdr_csum = 0;
+    Word global_csum = 0;
+    Byte hdr_csum = 0;
     Byte *mem;
 
     if (!fp)
@@ -374,35 +373,43 @@ int GBOutput(const char *filename, const char *filename_bank,
 
     /* Header checksum
     */
+    hdr_csum = 0;
+
     for(f = 0x134 ; f < 0x14d; f++)
     {
-        hdr_csum -= mem[f] - 1;
+        hdr_csum = hdr_csum - mem[f] - 1u;
     }
 
     PokeB(mem, 0x14d, hdr_csum);
 
     /* Global checksum
     */
+    global_csum = 0;
+
     if (count == 1)
     {
-        for(f = 0; f < 0x8000; f++)
+        for(f = 0; f < 0x14e; f++)
         {
-            if (f < 0x14e || f > 0x14f)
-            {
-                global_csum += mem[f];
-            }
+            global_csum += mem[f];
+        }
+
+        for(f = 0x150; f < 0x8000; f++)
+        {
+            global_csum += mem[f];
         }
     }
     else
     {
         int r;
 
-        for(f = 0; f < 0x4000; f++)
+        for(f = 0; f < 0x14e; f++)
         {
-            if (f < 0x14e || f > 0x14f)
-            {
-                global_csum += mem[f];
-            }
+            global_csum += mem[f];
+        }
+
+        for(f = 0x150; f < 0x4000; f++)
+        {
+            global_csum += mem[f];
         }
 
         for(r = 1; r < count; r++)
@@ -414,7 +421,8 @@ int GBOutput(const char *filename, const char *filename_bank,
         }
     }
 
-    PokeW(mem, 0x14e, global_csum);
+    PokeB(mem, 0x14e, global_csum >> 8);
+    PokeB(mem, 0x14f, global_csum);
 
     /* Output the ROM contents
     */