# HG changeset patch
# User John Tsiombikas <nuclear@member.fsf.org>
# Date 1519207213 -7200
# Node ID 51422ea54b9d0b7d074b9f3dfcd58953eacacc94

initial commit

diff -r 000000000000 -r 51422ea54b9d Makefile
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Makefile	Wed Feb 21 12:00:13 2018 +0200
@@ -0,0 +1,35 @@
+asrc = $(wildcard src/*.s)
+obj = $(asrc:.s=.o)
+
+name = test
+elf = $(name).elf
+bin = $(name).bin
+adf = $(name).adf
+bootblock = boot.bin
+
+tool_prefix = m68k-linux-gnu-
+
+CC = $(tool_prefix)gcc
+AS = $(tool_prefix)as
+LD = $(tool_prefix)ld
+OBJCOPY = $(tool_prefix)objcopy
+
+ASFLAGS = -m68000
+LDFLAGS = -T amiga.ld -print-gc-sections \
+		  -L/usr/lib/gcc-cross/m68k-linux-gnu/6 -lgcc
+
+$(adf): $(bin) $(bootblock)
+	tools/mk_adf.py $(bootblock) $(bin) $@
+
+$(bin): $(elf)
+	$(OBJCOPY) -O binary $< $@
+
+$(elf): $(obj)
+	$(LD) -o $@ $(obj) -Map link.map $(LDFLAGS)
+
+$(bootblock): src/boot/boot.o
+	$(OBJCOPY) -O binary $< $@
+
+.PHONY: clean
+clean:
+	rm -f $(obj) $(bin) $(elf)
diff -r 000000000000 -r 51422ea54b9d amiga.ld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/amiga.ld	Wed Feb 21 12:00:13 2018 +0200
@@ -0,0 +1,27 @@
+OUTPUT_ARCH(m68k)
+
+MEMORY
+{
+	chipram : ORIGIN = 0, LENGTH = 0x80000
+}
+
+PROVIDE (_stacktop = 0x80000);
+
+SECTIONS {
+	/* bootblock will load us at 100h, after the interrupt vectors */
+	. = 0x100;
+
+	.text : { * (.text); } >chipram
+	.rodata : { * (.rodata); } >chipram
+	.data : { * (.data); } >chipram
+
+	.bss ALIGN(4): {
+		_bss_start = .;
+		* (.bss);
+		. = ALIGN(4);
+		_bss_end = .;
+	} >chipram
+	_bss_size = SIZEOF(.bss);
+
+	.dummy ALIGN(4): { LONG(42); } >chipram
+}
diff -r 000000000000 -r 51422ea54b9d src/boot/boot.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/boot/boot.s	Wed Feb 21 12:00:13 2018 +0200
@@ -0,0 +1,24 @@
+| vi:filetype=gas68k:
+
+	.equ CMD_READ, 2
+
+	.equ EXEC_DO_IO, -0x1c8
+
+| starting with trackdisk device I/O request pointer in a1
+| load the program at 0x100 and return with that value in a0
+| program length is patched by mk_adf at start - 4
+start:
+	move.l #0x100, 0x28(%a1)	| I/O data pointer
+	move.l start - 4, 0x24(%a1)	| I/O length (1 sector for now)
+	move.l #512, 0x2c(%a1)		| I/O offset (skip first sector)
+	move.w #CMD_READ, 0x1c(%a1)	| I/O command
+	move.l %a1, -(%sp)
+	jsr EXEC_DO_IO(%a6)
+	move.l (%sp)+, %a1
+	move.b 0x1f(%a1), %d0
+
+	move.l #0x100, %a0
+	rts
+
+	.ascii "bootblock_end"
+	.align 4
diff -r 000000000000 -r 51422ea54b9d src/startup.s
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/startup.s	Wed Feb 21 12:00:13 2018 +0200
@@ -0,0 +1,27 @@
+| vi:filetype=gas68k:
+	.text
+
+	.equ REG_COL0, 0xdff180
+
+	.global start
+	.global halt_cpu
+
+start:
+	| zero the .bss section
+	move.l #_bss_start, %a0
+	move.l #_bss_end, %a1
+	cmp.l %a0, %a1
+	beq.s 1f	| skip zeroing if the section is empty
+0:	clr.l (%a0)+
+	cmp.l %a0, %a1
+	bne.s 0b
+1:
+	| setup the stack
+	move.l #_stacktop, %sp
+
+	| test output
+	move.w #0xf0f, REG_COL0
+0:	bra.b 0b	| infloop
+
+halt_cpu:
+	stop #0x2700
diff -r 000000000000 -r 51422ea54b9d tools/mk_adf.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/mk_adf.py	Wed Feb 21 12:00:13 2018 +0200
@@ -0,0 +1,56 @@
+#!/usr/bin/python
+# mk_adf.py <bootblock> <payload> <output_adf>
+#
+# Stuff a given bootblock and payload into an output ADF image.
+# 
+# Written & released by Keir Fraser <keir.xen@gmail.com>
+# 
+# This is free and unencumbered software released into the public domain.
+# See the file COPYING for more details, or visit <http://unlicense.org>.
+
+import struct, sys
+
+# Amiga bootblock checksum
+def checksum(bb, sum=0):
+    while len(bb):
+        x, bb = struct.unpack(">L",bb[:4]), bb[4:]
+        sum += x[0]
+        if sum >= (1<<32):
+            sum -= (1<<32)-1
+    return sum
+
+def main(argv):
+    bb_f = open(argv[1], "rb")
+    pl_f = open(argv[2], "rb")
+    out_f = open(argv[3], "wb")
+    bb_dat = bb_f.read()
+    pl_dat = pl_f.read()
+
+    # Construct bootblock header. We will splice in the checksum later.
+    header = struct.pack(">ccccLLLL",
+                         'D', 'O', 'S', '\0',         # Bootblock signature
+                         0,                           # Checksum (placeholder)
+                         880,                         # Root block
+                         0x60060000,                  # BRA.B +6
+                         (len(pl_dat) + 511) & ~511)  # Payload length, padded
+                         
+    
+    # Compute checksum over header, bootblock, and first 512 bytes of payload.
+    sum = checksum(pl_dat[:512], checksum(bb_dat, checksum(header)))
+    sum ^= 0xFFFFFFFF
+    # Splice the computed checksum into the header
+    header = header[:4] + struct.pack(">L", sum) + header[8:]
+    # Write out the header and bootblock code
+    out_f.write(header)
+    out_f.write(bb_dat)
+    # Pad bootblock to 512 bytes
+    for x in xrange((512-len(bb_dat)-len(header))/4):
+        out_f.write(struct.pack(">L", 0))
+    # Write the payload from sector 1 onwards
+    out_f.write(pl_dat)
+    # Pad the ADF image to 880kB
+    for x in xrange((901120-len(pl_dat)-512)/4):
+        out_f.write(struct.pack(">L", 0))
+        
+if __name__ == "__main__":
+    main(sys.argv)