From 94fd86135077db5979af3694cf427dff6ff4df0c Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Tue, 12 Dec 2023 06:59:32 +0200
Subject: [PATCH] Z80/snd init

---
 .gitignore          |    1 +
 Makefile            |   20 ++++++++++++++++++++
 src/hwregs.h        |   16 ++++++++++++++++
 src/intr.s          |    5 +++++
 src/libc/inttypes.h |   12 ++++++++++++
 src/main.c          |    4 ++++
 src/z80.c           |   24 ++++++++++++++++++++++++
 src/z80.h           |   15 +++++++++++++++
 src/z80/main.asm    |   36 ++++++++++++++++++++++++++++++++++++
 src/z80/sndregs.inc |   20 ++++++++++++++++++++
 src/z80prog.s       |   10 ++++++++++
 z80.ld              |   20 ++++++++++++++++++++
 12 files changed, 183 insertions(+)
 create mode 100644 src/hwregs.h
 create mode 100644 src/libc/inttypes.h
 create mode 100644 src/z80.c
 create mode 100644 src/z80.h
 create mode 100644 src/z80/main.asm
 create mode 100644 src/z80/sndregs.inc
 create mode 100644 src/z80prog.s
 create mode 100644 z80.ld

diff --git a/.gitignore b/.gitignore
index d11753f..95a7ed6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@
 *.bin
 *.elf
 *.map
+*.z80
diff --git a/Makefile b/Makefile
index 002cba4..e6043d4 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,10 @@ aSsrc = $(wildcard src/*.S)
 obj = $(asrc:.s=.o) $(aSsrc:.S=.o) $(csrc:.c=.o)
 dep = $(csrc:.c=.d)
 
+z80src = $(wildcard src/z80/*.asm)
+z80obj = $(z80src:.asm=.z80)
+z80bin = z80.bin
+
 name = life
 elf = $(name).elf
 bin = $(name).bin
@@ -27,17 +31,32 @@ ASFLAGS = -m68000 $(inc)
 LDFLAGS = -T megadrive.ld -print-gc-sections \
 		  -L/usr/lib/gcc-cross/m68k-linux-gnu/11 -lgcc
 
+Z80AS = vasmz80_oldstyle
+Z80ASFLAGS = -Fvobj
+Z80LD = vlink
+Z80LDFLAGS = -T z80.ld -b rawbin1
+
+
 $(bin): $(elf)
 	$(OBJCOPY) -O binary $< $@
 
 $(elf): $(obj)
 	$(LD) -o $@ $(obj) -Map link.map $(LDFLAGS)
 
+$(z80bin): $(z80obj)
+	$(Z80LD) -o $@ $(Z80LDFLAGS) $(z80obj)
+
+src/z80prog.o: src/z80prog.s $(z80bin)
+
 -include $(dep)
 
+%.z80: %.asm
+	$(Z80AS) -o $@ $(Z80ASFLAGS) $< >/dev/null
+
 .PHONY: clean
 clean:
 	rm -f $(obj) $(elf) $(bin)
+	rm -f $(z80obj) $(z80bin)
 
 .PHONY: cleandep
 cleandep:
@@ -57,3 +76,4 @@ install: $(bin)
 	mount /media/usbmass
 	[ -f /media/usbmass/MEGA/MEGA.RBF ] || cp $(bin) /media/usbmass/MEGA/MEGA.BIN
 	umount /media/usbmass
+
diff --git a/src/hwregs.h b/src/hwregs.h
new file mode 100644
index 0000000..834be05
--- /dev/null
+++ b/src/hwregs.h
@@ -0,0 +1,16 @@
+#ifndef HWREGS_H_
+#define HWREGS_H_
+
+#include <inttypes.h>
+
+#define REG16PTR(addr)	(*(volatile uint16_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)
+
+#endif	/* HWREGS_H_ */
diff --git a/src/intr.s b/src/intr.s
index 8f4f01e..6dc8433 100644
--- a/src/intr.s
+++ b/src/intr.s
@@ -72,6 +72,7 @@
 | from here on we continue in the regular .text section since we don't care
 | where this code ends up.
 	.text
+	.include "vdpdefs.inc"
 
 .global enable_intr
 enable_intr:
@@ -90,6 +91,7 @@ intr_fatal:
 |	.extern vblank_handler
 
 intr_hblank:
+|	move.l %d0, -(%sp)
 |	move.l #0xc0020000, VDP_PORT_CTL
 |
 |	move.w testcol, %d0
@@ -97,8 +99,11 @@ intr_hblank:
 |	rol.b #4, %d0
 |	move.w %d0, testcol
 |
+|	move.l (%sp)+, %d0
 	rte
 
+|testcol: .word 0
+
 intr_vblank:
 |	jsr vblank_handler
 	rte
diff --git a/src/libc/inttypes.h b/src/libc/inttypes.h
new file mode 100644
index 0000000..fcbf7e1
--- /dev/null
+++ b/src/libc/inttypes.h
@@ -0,0 +1,12 @@
+#ifndef INTTYPES_H_
+#define INTTYPES_H_
+
+typedef signed char int8_t;
+typedef short int16_t;
+typedef long int32_t;
+
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+typedef unsigned long uint32_t;
+
+#endif	/* INTTYPES_H_ */
diff --git a/src/main.c b/src/main.c
index 31dbf45..34f8626 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,4 +1,8 @@
+#include "z80.h"
+
 int main(void)
 {
+	z80_init();
+
 	return 0;
 }
diff --git a/src/z80.c b/src/z80.c
new file mode 100644
index 0000000..32ce82e
--- /dev/null
+++ b/src/z80.c
@@ -0,0 +1,24 @@
+#include "z80.h"
+
+extern unsigned char z80prog[];
+extern long z80proglen;
+
+void z80_init(void)
+{
+	int i;
+	unsigned char *src, *dest;
+
+	z80_grab_bus();
+	z80_reset(0);
+	while(!z80_have_bus());
+
+	src = z80prog;
+	dest = Z80_MEM;
+	for(i=0; i<z80proglen; i++) {
+		*dest++ = *src++;
+	}
+
+	z80_reset(1);
+	z80_release_bus();
+	z80_reset(0);
+}
diff --git a/src/z80.h b/src/z80.h
new file mode 100644
index 0000000..98e0165
--- /dev/null
+++ b/src/z80.h
@@ -0,0 +1,15 @@
+#ifndef Z80_H_
+#define Z80_H_
+
+#include "hwregs.h"
+
+void z80_init(void);
+
+#define z80_grab_bus()		(Z80_BUSREQ = 0x100)
+#define z80_release_bus()	(Z80_BUSREQ = 0)
+/* non-zero if 68k grabbed the bus */
+#define z80_have_bus()		((Z80_BUSREQ & 0x100) == 0)
+
+#define z80_reset(rst)		(Z80_RESET = ((rst) ? 0 : 0x100))
+
+#endif	/* Z80_H_ */
diff --git a/src/z80/main.asm b/src/z80/main.asm
new file mode 100644
index 0000000..969559a
--- /dev/null
+++ b/src/z80/main.asm
@@ -0,0 +1,36 @@
+	include "sndregs.inc"
+
+	section .vect
+	jp main
+
+	org 38h
+	jp vblank_isr
+
+	section .text
+main:	di
+	ld sp, $2000
+	im 1
+	ei
+.hang:	halt
+	jr .hang
+
+init:
+	call ymwait
+	ret
+
+ymwait:
+	ld hl, YMADDR
+.wait:	ld a, (hl)
+	bit 7, a
+	jr z, .wait
+	ret
+
+
+vblank_isr:
+	;ex af, af'
+
+	;ex af, af'
+	;ei
+	ret
+
+; vi:ft=z80:
diff --git a/src/z80/sndregs.inc b/src/z80/sndregs.inc
new file mode 100644
index 0000000..4efe4d1
--- /dev/null
+++ b/src/z80/sndregs.inc
@@ -0,0 +1,20 @@
+YMADDR	equ $4000
+YMDATA	equ $4001
+YMADDR2	equ $4002
+YMDATA2	equ $4003
+
+YM_LFO		equ $22
+YM_TIMERA_L	equ $24
+YM_TIMERA_H	equ $25
+YM_TIMERB	equ $26
+YM_MODE		equ $27
+YM_OPER		equ $28
+YM_DAC		equ $2a
+YM_DACEN	equ $2b
+
+YM_OP1_DT1MUL	equ $30
+YM_OP2_DT1MUL	equ $34
+YM_OP3_DT1MUL	equ $38
+YM_OP4_DT1MUL	equ $3c
+
+; vi:ft=z80:
diff --git a/src/z80prog.s b/src/z80prog.s
new file mode 100644
index 0000000..cb4c961
--- /dev/null
+++ b/src/z80prog.s
@@ -0,0 +1,10 @@
+	.section .rodata
+
+	.globl z80prog
+	.globl z80proglen
+
+z80prog:
+	.incbin "z80.bin"
+	.align 2
+z80proglen:
+	.long z80prog - z80proglen
diff --git a/z80.ld b/z80.ld
new file mode 100644
index 0000000..3f31ebf
--- /dev/null
+++ b/z80.ld
@@ -0,0 +1,20 @@
+MEMORY {
+	ram : ORIGIN = 0, LENGTH = 0x2000
+}
+
+SECTIONS {
+	/* reset and interrupt vectors */
+	.vect : { * (.vect); }
+	/* we only need vectors up to 38h for IM 1 */
+	. = 0x40;
+	.text : { * (.text*); }
+	.rodata : { * (.rodata); }
+	.data : { * (.data); }
+	.bss : {
+		_bss_start = .;
+		* (.bss);
+		. = ALIGN(2)
+		_bss_end = .;
+	}
+	_bss_size = SIZEOF(.bss);
+}
-- 
1.7.10.4