From 6513a329c0b984945a50735a871abc5b7f08ec46 Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Thu, 14 Dec 2023 20:46:51 +0200
Subject: [PATCH] clear red

---
 src/hwregs.h |   93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 src/main.c   |    4 +++
 src/vdp.S    |   71 ++++++++++++++++++++++++++++++++++++++++++++
 src/vdp.h    |   19 ++++++++++++
 4 files changed, 185 insertions(+), 2 deletions(-)
 create mode 100644 src/vdp.S
 create mode 100644 src/vdp.h

diff --git a/src/hwregs.h b/src/hwregs.h
index 834be05..6dd8a74 100644
--- a/src/hwregs.h
+++ b/src/hwregs.h
@@ -1,16 +1,105 @@
 #ifndef HWREGS_H_
 #define HWREGS_H_
 
+#define VDP_DATA_PORT	0xc00000
+#define VDP_CTL_PORT	0xc00004
+
+/* VDP access type */
+#define VDP_VRAM	0x40000000
+#define VDP_CRAM	0xc0000000
+#define VDP_VSRAM	0x40000010
+
+#ifndef ASM
 #include <inttypes.h>
 
 #define REG16PTR(addr)	(*(volatile uint16_t*)(addr))
+#define REG32PTR(addr)	(*(volatile uint32_t*)(addr))
 
 #define Z80_MEMMODE			REG16PTR(0xa11000)
 #define Z80_BUSREQ			REG16PTR(0xa11100)
 #define Z80_RESET			REG16PTR(0xa11200)
 #define Z80_MEM				((uint8_t*)0xa00000)
 
-#define VDP_PORT_DATA		REG16PTR(0xc00000)
-#define VDP_PORT_CTL		REG16PTR(0xc00004)
+#define VDP_DATA		REG16PTR(VDP_DATA_PORT)
+#define VDP_CTL			REG16PTR(VDP_CTL_PORT)
+#define VDP_CTL32		REG32PTR(VDP_CTL_PORT)
+#define VDP_STAT		VDP_CTL
+#endif	/* !def ASM */
+
+#define VDP_REG_MODE1		0
+#define VDP_REG_MODE2		1
+#define VDP_REG_NAMEA		2
+#define VDP_REG_NAMEW		3
+#define VDP_REG_NAMEB		4
+#define VDP_REG_SPR			5
+#define VDP_REG_BGCOL		7
+#define VDP_REG_HINTR		10
+#define VDP_REG_MODE3		11
+#define VDP_REG_MODE4		12
+#define VDP_REG_HSCROLL		13
+#define VDP_REG_AUTOINC		15
+#define VDP_REG_SCROLLSZ	16
+#define VDP_REG_WINX		17
+#define VDP_REG_WINY		18
+#define VDP_REG_DMACNTL		19
+#define VDP_REG_DMACNTH		20
+#define VDP_REG_DMASRCL		21
+#define VDP_REG_DMASRCM		22
+#define VDP_REG_DMASRCH		23
+
+#define VDP_ST_PAL		0x001
+#define VDP_ST_DMA		0x002
+#define VDP_ST_HBLANK	0x004
+#define VDP_ST_VBLANK	0x008
+#define VDP_ST_ODDFRM	0x010
+#define VDP_ST_COL		0x020
+#define VDP_ST_SPROVF	0x040
+#define VDP_ST_VINTR	0x080
+#define VDP_ST_FULL		0x100
+#define VDP_ST_EMPT		0x200
+
+#define VDP_M1_INIT		0x04
+#define VDP_M1_HVSTOP	0x02
+#define VDP_M1_HINTR	0x10
+
+#define VDP_M2_INIT		0x04
+#define VDP_M2_V30		0x08
+#define VDP_M2_DMA		0x10
+#define VDP_M2_VINTR	0x20
+#define VDP_M2_DISP		0x40
+
+#define VDP_NA_ADDR(x)	(((x) >> 14) & 0x38)
+#define VDP_NW_ADDR(x)	(((x) >> 14) & 0x3e)
+#define VDP_NB_ADDR(x)	((x) >> 17)
+#define VDP_SPRTAB_ADDR(x)	((x) >> 9)
+#define VDP_HSTAB_ADDR(x)	((x) >> 10)
+
+#define VDP_BGCOL(pal, col)	(((pal) << 4) | (col))
+
+#define VDP_M3_HFULL	0
+#define VDP_M3_HCELL	0x02
+#define VDP_M3_HLINE	0x03
+#define VDP_M3_VFULL	0
+#define VDP_M3_V2CELL	0x04
+#define VDP_M3_EXTINTR	0x08
+
+#define VDP_M4_H40		0x81
+#define VDP_M4_ILACE	0x02
+#define VDP_M4_ILACE2X	0x06
+#define VDP_M4_SHAD		0x08
+
+#define VDP_SCR_H32		0
+#define VDP_SCR_H64		0x01
+#define VDP_SCR_H128	0x03
+#define VDP_SCR_V32		0
+#define VDP_SCR_V64		0x10
+#define VDP_SCR_V128	0x30
+
+#define VDP_WINX_RIGHT	0x80
+#define VDP_WINY_DOWN	0x80
+
+#define VDP_DMA_MEM		0
+#define VDP_DMA_FILL	0x80
+#define VDP_DMA_COPY	0xc0
 
 #endif	/* HWREGS_H_ */
diff --git a/src/main.c b/src/main.c
index 34f8626..9816bda 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,8 +1,12 @@
 #include "z80.h"
+#include "vdp.h"
 
 int main(void)
 {
 	z80_init();
+	vdp_init();
+
+	vdp_setcolor(0, 0, 14, 0, 0);
 
 	return 0;
 }
diff --git a/src/vdp.S b/src/vdp.S
new file mode 100644
index 0000000..b794d21
--- /dev/null
+++ b/src/vdp.S
@@ -0,0 +1,71 @@
+	.text
+
+#define ASM
+#include "hwregs.h"
+
+	.globl vdp_init
+vdp_init:
+	move.l #def_reg_tab, %a0
+	move.w #0, %d1
+0:	move.w %d1, %d0
+	lsl.w #8, %d0
+	or.w #0x8000, %d0
+	move.b (%a0)+, %d0
+	move.w %d0, VDP_CTL_PORT	| VDP_CTL = 0x8000 | (reg << 8) | val
+	add.w #1, %d1
+	cmp.w def_reg_tab_size, %d1
+	bne.s 0b
+	rts
+
+	| address in d0, type in d1
+setup_addr:
+	lsl.l #2, %d0
+	lsr.w #2, %d0
+	swap %d0
+	or.l %d1, %d0
+	move.l %d0, VDP_CTL_PORT
+	rts
+
+	.globl vdp_setcolor
+vdp_setcolor:
+	move.l 4(%sp), %d0	| palette number
+	lsl.l #4, %d0
+	add.l 8(%sp), %d0	| add index
+	move.l #VDP_CRAM, %d1
+	bsr setup_addr
+	move.w 22(%sp), %d0	| blue
+	lsl.w #4, %d0
+	or.w 18(%sp), %d0	| green
+	lsl.w #4, %d0
+	or.w 14(%sp), %d0	| red
+	and.w #0x0eee, %d0
+	move.w %d0, VDP_DATA_PORT
+	rts
+
+	.data
+def_reg_tab:
+	.byte VDP_M1_INIT			| 0: mode 1
+	.byte VDP_M2_INIT + VDP_M2_DISP		| 1: mode 2
+	.byte VDP_NA_ADDR(0xc000)		| 2: scroll A nametable addr.
+	.byte 0					| 3: window nametable addr.
+	.byte VDP_NB_ADDR(0xd000)		| 4: scroll B nametable addr.
+	.byte VDP_SPRTAB_ADDR(0xe000)		| 5: sprite table addr.
+	.byte 0
+	.byte 0					| 7: bg color
+	.byte 0, 0
+	.byte 0					| 10: horiz. interrupt interval
+	.byte 0					| 11: mode 3
+	.byte VDP_M4_H40			| 12: mode 4
+	.byte 0					| 13: hscroll table addr.
+	.byte 0
+	.byte 2					| 15: autoincrement 2 bytes
+	.byte VDP_SCR_H64			| 16: scroll size (64x32)
+	.byte 0, 0				| 17,18: win x/y pos
+	.byte 0, 0, 0, 0, 0			| 19-23: DMA regs
+def_reg_tab_end:
+	.align 2
+def_reg_tab_size:
+	.word def_reg_tab_end - def_reg_tab
+
+	
+| vi:ft=gas68k:
diff --git a/src/vdp.h b/src/vdp.h
new file mode 100644
index 0000000..74199a1
--- /dev/null
+++ b/src/vdp.h
@@ -0,0 +1,19 @@
+#ifndef VDP_H_
+#define VDP_H_
+
+#include "hwregs.h"
+
+#define VDP_VRAM	0x40000000
+#define VDP_CRAM	0xc0000000
+#define VDP_VSRAM	0x40000010
+
+#define vdp_setup_addr(type, addr) \
+	(VDP_CTL32 = ((type) | (((addr) & 0x3fff) << 16) | (((addr) >> 14) & 3)))
+
+#define vdp_setreg(reg, val) \
+	(VDP_CTL = 0x8000 | ((reg) << 8) | (val))
+
+void vdp_init(void);
+void vdp_setcolor(int pal, int cidx, int r, int g, int b);
+
+#endif	/* VDP_H_ */
-- 
1.7.10.4