support for linking different disk and input drivers

Makefile

@@ -1,5 +1,7 @@
 
 VARIANT ?= bsw
+DRIVE ?= drv1541
+INPUT ?= joydrv
 
 AS=ca65
 LD=ld65
@@ -126,12 +128,12 @@ $(BUILD_DIR)/kernal_compressed.prg: $(BUILD_DIR)/kernal_combined.prg
  pucrunch -f -c64 -x0x5000 $< $@ 2> /dev/null
 
 $(BUILD_DIR)/kernal_combined.prg: $(ALL_BINS)
- @echo Creating $@
+ @echo Creating $@ from kernal.bin $(DRIVE).bin $(INPUT).bin
  @printf "\x00\x50" > $(BUILD_DIR)/tmp.bin
  @dd if=$(BUILD_DIR)/kernal/kernal.bin bs=1 count=16384 >> $(BUILD_DIR)/tmp.bin 2> /dev/null
- @cat $(BUILD_DIR)/drv/drv1541.bin /dev/zero | dd bs=1 count=3456 >> $(BUILD_DIR)/tmp.bin 2> /dev/null
+ @cat $(BUILD_DIR)/drv/$(DRIVE).bin /dev/zero | dd bs=1 count=3456 >> $(BUILD_DIR)/tmp.bin 2> /dev/null
  @cat $(BUILD_DIR)/kernal/kernal.bin /dev/zero | dd bs=1 count=24832 skip=19840 >> $(BUILD_DIR)/tmp.bin 2> /dev/null
- @cat $(BUILD_DIR)/input/joydrv.bin >> $(BUILD_DIR)/tmp.bin 2> /dev/null
+ @cat $(BUILD_DIR)/input/$(INPUT).bin >> $(BUILD_DIR)/tmp.bin 2> /dev/null
  @mv $(BUILD_DIR)/tmp.bin $(BUILD_DIR)/kernal_combined.prg
 
 $(BUILD_DIR)/drv/drv1541.bin: $(BUILD_DIR)/drv/drv1541.o drv/drv1541.cfg $(DEPS)
@@ -163,7 +165,7 @@ $(BUILD_DIR)/input/pcanalog.bin: $(BUILD_DIR)/input/pcanalog.o input/pcanalog.cf
 
 $(BUILD_DIR)/%.o: %.s
  @mkdir -p `dirname $@`
- $(AS) -D $(VARIANT)=1 $(ASFLAGS) $< -o $@
+ $(AS) -D $(VARIANT)=1 -D $(DRIVE)=1 -D $(INPUT)=1 $(ASFLAGS) $< -o $@
 
 $(BUILD_DIR)/kernal/kernal.bin: $(PREFIXED_KERNAL_OBJS) kernal/kernal_$(VARIANT).cfg
  @mkdir -p $$(dirname $@)

README.md

@@ -105,6 +105,15 @@ You can build a specific variant like this:
 
 All output will be put into `build/<variant>`.
 
+## Drivers
+
+By default, the KERNAL image will contain the Commodore 1541 disk driver (`drv1541`) and the joystick input driver (`joydrv`). You can specify different drivers to be included like this:
+
+ make DRIVE=<drive> INPUT=<input>
+
+Supported drives are `drv1541`, `drv1571` and `drv1581`. Supported input devices are `amigamse`, `joydrv`, `koalapad`, `lightpen`, `mse1531` and `pcanalog`.
+
+
 ## Customization
 
 The KERNAL variant `custom` is meant for your experimentation. Inside the `.ifdef custom` section in `config.inc`, you can toggle several compile time options:

config.inc

@@ -147,3 +147,13 @@ useRamExp = 1
 .else
 REUPresent = 1
 .endif
+
+.if .defined(drv1541)
+DRV_TYPE = 1 ; DRV_1541
+.elseif .defined(drv1571)
+DRV_TYPE = 2; DRV_1571
+.elseif .defined(drv1581)
+DRV_TYPE = 3; DRV_1581
+.else
+.error "Unknown drive type!"
+.endif

kernal/start.s

@@ -56,7 +56,6 @@
 ; everything work.
 ;
 ; TODO: * REU detection seems to be currently missing.
-; * This is hardcoded to a 1541 drive.
 ; * It would be best to put the original GEOS 2.0 code
 ; here.
 ;
@@ -131,7 +130,7 @@ ASSERT_NOT_BELOW_IO
  sta NUMDRV
  ldy $BA
  sty curDrive
- lda #DRV_1541
+ lda #DRV_TYPE ; see config.inc
  sta curType
  sta _driveType,y