# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1485757313 -7200
# Node ID 909c22dc18d26180e233216c14d4f476b6c1d284

initial commit

diff -r 000000000000 -r 909c22dc18d2 .hgignore
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.hgignore	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,6 @@
+\.o$
+\.d$
+\.swp$
+\.elf$
+\.bin$
+link\.map$
diff -r 000000000000 -r 909c22dc18d2 Makefile
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Makefile	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,32 @@
+asrc = $(wildcard src/*.s)
+aSsrc = $(wildcard src/*.S)
+obj = $(asrc:.s=.o) $(aSsrc:.S=.o)
+
+name = test1
+elf = $(name).elf
+bin = $(name).bin
+
+warn = -pedantic -Wall
+dbg = -g
+def = -DGAMENAME=\"testgame\" -DVERSTR=\"01\"
+
+tool_prefix = m68k-linux-gnu-
+
+CC = $(tool_prefix)gcc
+AS = $(tool_prefix)as
+LD = $(tool_prefix)ld
+OBJCOPY = $(tool_prefix)objcopy
+
+CFLAGS = -m68000 -nostdinc -fno-builtin $(warn) $(dbg) $(opt) $(def)
+ASFLAGS = -m68000
+LDFLAGS = -T megadrive.ldscript -print-gc-sections
+
+$(bin): $(elf)
+	$(OBJCOPY) -O binary $< $@
+
+$(elf): $(obj)
+	$(LD) -o $@ $(LDFLAGS) $(obj) -Map link.map
+
+.PHONY: clean
+clean:
+	rm -f $(obj) $(elf) $(bin)
diff -r 000000000000 -r 909c22dc18d2 megadrive.ldscript
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/megadrive.ldscript	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,44 @@
+OUTPUT_ARCH(m68k)
+
+MEMORY
+{
+	rom : ORIGIN = 0x00000000, LENGTH = 0x00a00000
+	ram : ORIGIN = 0x00ff0000, LENGTH = 0x00010000
+}
+
+PROVIDE (_stacktop = 0x01000000);
+
+SECTIONS {
+	/* ---- start of ROM ---- */
+	/* .vect section is used to place the m68k exception vectors at the
+	 * beginning of the address space
+	 */
+	.vect : { KEEP (* (.vect)); } >rom
+	/* .romhdr section is used to place the SEGA ROM header at 0x100 */
+	. = 0x100;
+	.romhdr : { KEEP (* (.romhdr)); } >rom
+	.text : { * (.text); } >rom
+	.rodata : { * (.rodata); } >rom
+
+	/* place the load address of the .data section after .rodata */
+	_data_lma = .;
+	_rom_end = _data_lma + _data_size;
+
+	/* ---- start of RAM ---- */
+	. = 0xff0000;
+	/* place the .data section at the start of RAM */
+	.data : AT (_data_lma) {
+		_data_start = .;
+		* (.data);
+		_data_end = .;
+	} >ram
+	_data_size = SIZEOF(.data);
+
+	/* place the .bss section at the end */
+	.bss : {
+		_bss_start = .;
+		* (.bss);
+		_bss_end = .;
+	} >ram
+	_bss_size = SIZEOF(.bss);
+}
diff -r 000000000000 -r 909c22dc18d2 src/intr.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/intr.s	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,82 @@
+| the following will go into the .vect section which will be placed at the very
+| begining of the binary at address 0 by the linker (see lnkscript).
+	.section .vect,"a"
+	.extern start
+| exception vectors
+	.long _stacktop		| 00 reset - initial SSP
+	.long start		| 01 reset - initial PC
+	.long intr_fatal	| 02 bus error
+	.long intr_fatal	| 03 address error
+	.long intr_fatal	| 04 illegal instruction
+	.long intr_fatal	| 05 zero divide
+	.long intr_fatal	| 06 chk instruction
+	.long intr_fatal	| 07 trapv instruction
+	.long intr_fatal	| 08 privilege violation
+	.long intr_fatal	| 09 trace
+	.long intr_fatal	| 0a line 1010 emulator
+	.long intr_fatal	| 0b line 1111 emulator
+	.long intr_fatal	| 0c reserved
+	.long intr_fatal	| 0d reserved
+	.long intr_fatal	| 0e format error (mc68010 only)
+	.long intr_fatal	| 0f uninitialized interrupt vector
+	.long intr_fatal	| 10 \
+	.long intr_fatal	| 11 |
+	.long intr_fatal	| 12 |
+	.long intr_fatal	| 13  > reserved
+	.long intr_fatal	| 14 |
+	.long intr_fatal	| 15 |
+	.long intr_fatal	| 16 |
+	.long intr_fatal	| 17 /
+	.long intr_fatal	| 18 spurious interrupt 
+	.long intr_fatal	| 19 level 1 interrupt
+	.long intr_fatal	| 1a level 2 interrupt
+	.long intr_fatal	| 1b level 3 interrupt
+	.long intr_hblank	| 1c level 4 interrupt (hblank in the mega drive)
+	.long intr_fatal	| 1d level 5 interrupt
+	.long intr_vblank	| 1e level 6 interrupt (vblank in the mega drive)
+	.long intr_fatal	| 1f level 7 interrupt
+	.long intr_fatal	| 20 trap 0
+	.long intr_fatal	| 21 trap 1
+	.long intr_fatal	| 22 trap 2
+	.long intr_fatal	| 23 trap 3
+	.long intr_fatal	| 24 trap 4
+	.long intr_fatal	| 25 trap 5
+	.long intr_fatal	| 26 trap 6
+	.long intr_fatal	| 27 trap 7
+	.long intr_fatal	| 28 trap 8
+	.long intr_fatal	| 29 trap 9
+	.long intr_fatal	| 2a trap a
+	.long intr_fatal	| 2b trap b
+	.long intr_fatal	| 2c trap c
+	.long intr_fatal	| 2d trap d
+	.long intr_fatal	| 2e trap e
+	.long intr_fatal	| 2f trap f
+	.long intr_fatal	| 30 \
+	.long intr_fatal	| 31 |
+	.long intr_fatal	| 32 |
+	.long intr_fatal	| 33 |
+	.long intr_fatal	| 34 |
+	.long intr_fatal	| 35 |
+	.long intr_fatal	| 36 |
+	.long intr_fatal	| 37 |
+	.long intr_fatal	| 38  > reserved
+	.long intr_fatal	| 39 |
+	.long intr_fatal	| 3a |
+	.long intr_fatal	| 3b |
+	.long intr_fatal	| 3c |
+	.long intr_fatal	| 3d |
+	.long intr_fatal	| 3e |
+	.long intr_fatal	| 3f /
+
+| from here on we continue in the regular .text section since we don't care
+| where this code ends up.
+	.text
+| interrupt handlers
+intr_fatal:
+	stop #0x2700
+
+| TODO hblank/vblank code
+intr_hblank:
+	rte
+intr_vblank:
+	rte
diff -r 000000000000 -r 909c22dc18d2 src/main.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main.s	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,4 @@
+	.text
+	.global main
+main:
+	rts
diff -r 000000000000 -r 909c22dc18d2 src/romhdr.S
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/romhdr.S	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,37 @@
+| the following will go into the custom .romhdr section which will be placed at
+| address 100 of the binary by the linker (see lnkscript).
+	.section .romhdr,"a"
+
+#ifndef GAMENAME
+#define GAMENAME "unnamed"
+#endif
+#ifndef VERSTR
+#define VERSTR "00"
+#endif
+
+	.ascii "SEGA MEGA DRIVE (C)MINDLAPSE2017"
+hdr_game_dom:
+	.ascii GAMENAME
+hdr_game_dom_end:
+	.fill 48 - (hdr_game_dom_end - hdr_game_dom),1,32 | pad to 48 bytes with spaces
+hdr_game_int:
+	.ascii GAMENAME
+hdr_game_int_end:
+	.fill 48 - (hdr_game_int_end - hdr_game_int),1,32 | pad to 48 bytes with spaces
+	.ascii "GM"		| it's a game (who cares what it is?)
+	.ascii "0000000-"	| product code
+	.ascii VERSTR		| version string
+	.short 0		| checksum
+	.ascii "J               " | I/O support (joypad)
+	.long 0			| start address of ROM
+	.long _rom_end		| last address of ROM
+	.long 0xff0000		| start address of RAM
+	.long 0xffffff		| last address of RAM
+	.long 0			| SRAM enabled(?)
+	.long 0			| ???
+	.long 0			| start address of SRAM
+	.long 0			| last address of SRAM
+	.long 0			| ???
+	.long 0			| ???
+	.fill 40,1,32		| notes (fill with spaces for now TODO)
+	.ascii "JUE             " | country codes
diff -r 000000000000 -r 909c22dc18d2 src/startup.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/startup.s	Mon Jan 30 08:21:53 2017 +0200
@@ -0,0 +1,8 @@
+| TODO: copy .data and zero .bss
+	.text
+	.extern main
+
+	.global start
+start:
+	jsr main
+	stop #0x2700